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  • 2010-2014
  • 1995-1999  (50)
  • 1980-1984  (1,224)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 61-67 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Risk assessments have been performed to determine the risk associated with the transportation of hazardous wastes through a city. In the course of these assessments, a number of modeling issues arose relating to transportation accident rates, the characterization of incidents, the effect of thermal radiation, the impact of exposure to toxic chemicals, and the threshold for acceptable risk. This paper discusses these issues.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. S3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 98-103 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents the design of ribbon wound pressure vessels useful for Ammonia, Urea and Methanol plants. The design is to create a thin shell of 1/5 the total wall thickness required, weld it to the end pieces, and wind 4 to 8 mm thick ribbons of 80 mm width at an angle of 15 to 30 degrees on the inner shell, using a prestress. The ribbons are welded at the ends and an even number of layers are wound cross-helically on to the shell. With more than 7000 vessels over the pressure range of 50 to 350 atmospheres in use in the various chemical industries in China over the past 30 years, their safety record has been excellent. Of particular interest has been the application of this technology in the Ammonia and Urea plants, where the design allows fabrication of these vessels at substantial reduction in cost, and early delivery, when compared to the mono wall technology.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 20-22 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most audits try to look at a representative selection of the plant procedures and equipment. An alternative is a survey, a look in depth at selected procedures (such as those for testing alarms and trips, issuing permits-to-work, controlling modifications, taking samples or testing relief devices) or selected equipment (such as level glasses or equipment for handling LPG). If the procedure or equipment is well-chosen, surveys may make a bigger contribution to safety, per person-hour, than a conventional audit.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 39-42 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Under OSHA 1910.119, all Process Safety Management (PSM) facilities are required to keep their pressure relief system design information current. This article demonstrates why a pressure relief system design verification effort must be based on an equipment list, rather than a relief device list, in order to ensure that every piece of equipment is adequately protected. The formerly common practice of simply checking the design bases of all existing relief devices is deficient is deficient since this technique does not systematically ensure that every piece of equipment is protected.The “Berwanger Method” is a step by step process for designing or analyzing a pressure relief system to meet OSHA 1910.119 Process Safety Information (PSI) and Process Hazard Analysis (PHA) mandates. The method uses a relational database which tracks the relationships between protected equipment, potential overpressure scenarios, and protective devices.The challenge facing an operating company does not end once the design basis has been “verified” - the design basis information must also be maintained and be readily accessible to avoid costly reinvention of the wheel down the road. The “Berwanger Method” also addresses these maintenance issues.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 49-60 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper reports on a comprehensive literature search and small scale experimental work on the reaction characteristics of phosphorous trichloride and water. More than 30 tests were conducted, including both closed and open test cells. The water to phosphorus trichloride molar ratio was varied from 1 to 25. When in contact, water and phosphorus trichloride will form two liquid layers with a reaction starting at the interface. The impact of variables on reaction rates including the interface surface area, layer depth, and stirring were investigated experimentally. A reaction rate model that fits all the measured data is presented. Case studies illustrating the use of this data for emergency relief systems and vent containment design are presented in reference. [1].
    Additional Material: 10 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 68-73 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two major accidents in the 80's: the summit Tunnel Fire, England and Piper Alpha disaster, an offshore platform in the North Sea; and very recently, possible explosion of the Boeing, TWA flight 800 at New York, makes it imperative that further research into the mechonisms of the ignition of flammable vapor/air mixture in contact with hot surfaces needs to be done. There have been a number of studies of ignition by hot surfaces, but in all these studies the ignition sources were wire, sphere or strip, i.e., most of them were flat surfaces. But to the authors' knowledge, other variables which affect the ignition mechanism such as irregular geometrical shapes have not been studied. The purpose of this paper is to examine how the degree of confinement (or, configuration), size and orientation, of the heated surface affects the ignition temperature of the flammable vapors. The results were obtained by experimentnal and by computational fluid dynamics.
    Additional Material: 13 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. S3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 9-15 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design and deflagration pressure relief vents is based on correlations developed for various types of combustible materials and for enclosures of different strengths. The primary guideline for deflagration vent design in the US is NFPA 68 Guide for Venting of Deflagrations [5]. That document gives guidance for the design of vents for enclosures containing flammable gases, specifically hydrogen, coke oven gas, propane, and methane. Application of the guide to other gases is achieved using the KG value. Values of KG are published for a relatively small number of gases, as seen in Table D-1 of NFPA 68. This work present KG data on several additional gases obtained in a laboratory scale test vessel along with analysis of the results with respect to published values of fundamental burning velocity.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 23-31 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In May 1996, the Flammable and Combustible Liquids Code Committee of the National Fire Protection Association (NFPA) proposed for adoption by the Association a new edition of NFPA 30, Flammable and Combustible Liquids Code. This new edition was the culmination of two and one-half years' work by the Committee and included one of the most significant changes to that document in some twenty years: the incorporation of mandatory fire protection criteria for warehouses and other inside areas that store flammable and combustible liquids in containers and portable tanks.
    Additional Material: 2 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 32-38 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes the development of a risk ranked Inspection Recommendation procedure that is used by one of Exxon's chemical plants to prioritize repairs that have been identified during equipment inspection.As part of the Company's Safety Management Practices initiative in the late 1980's a procedure was put into place to ensure that an Inspector's repair recommendations were properly addressed by the organization. The initial procedures were successful at “systematizing” the documentation and stewardship-to-completion of the Inspector's recommendation, however, there were complications with the original process: (1)The Inspector made a simple High, Medium or Low assessment of the priority/criticality of the recommendation. Frequently, this resulted in disagreements with Operations about the true priority of the recommendation.(2)If there was agreement on the priority of the recommendation, there was still disagreement on the relative rank within the priority-which high priority was the highest priority?(3)With limited funds to spend on repairs, it was (and is) important to make sure that the money was being spent on the highest risk items that had the greatest risk reduction/cost benefit ratio.To address these concerns, the procedure was modified to incorporate a risk assessment of the recommendation by both the Inspector and Operations. In the new procedure, the Inspector describes the deficiency that he/she finds and assesses the probability of failure within a certain time-frame. Operations must assess the consequences, from an environmental, safety and economics standpoint, were the failure to occur. These assessments are combined in the typical risk equation (risk = probability × consequences) to arrive at a severity index which serves to rank the recommendation relative to the other recommendations. Because Operations participates in the assessment there is very little disagreement about the priority of the recommendation. The severity index puts the recommendations in order so it is quite clear which are the highest priority recommendations. This process has helped to focus the entire organization on those deficiencies that represent the greatest risk with the result that less time and money is spent correcting items that have a low risk/cost benefit ratio, allowing these savings to be used to reduce the higher risks in the plant.
    Additional Material: 4 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 124-126 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple analytical method is presented for estimating the hybrid minimum ignition energy (HMIE) of dust-gas mixtures, based on the assumed generality of Bartknecht's well-known test data for mixtures of propane with a series of dusts in air. Since the HMIE equation requires input data which might be unavailable, the use of conservative default methods is discussed.
    Additional Material: 1 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 138-148 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A large and potentially hazardous decrease in aldehyde autoignition temperature (AIT) occurs with increased pressure. The AIT-pressure curve determined in a 5 L stainless steel sphere was similar for propionaldehyde and butyraldehyde in air, falling from about 185°C at atmospheric pressure to 90°C at 140 psia. Reduction of oxygen concentration had little effect on propionaldehyde AIT. At 100°C and 140 psia, autoignitions accompanied by at least a doubling of pressure were observed above 4% oxygen. In the presence of a few grams of free liquid, propionaldehyde vapor ignited in air at initial conditions significantly below the AIT. The mechanism appears to involve rapid Fe-catalyzed exothermic liquid-phase oxidation leading to autoignition of the adjacent heated gas layer. An acetaldehyde vapor-air mixture in the presence of free liquid and rust exploded at room temperature when air pressure was increased to 95 psia; this result is discussed with reference to a cylinder overpressurization that occurred while making up an ostensibly sub-LFL calibration mixture with compressed air. Propionaldehyde's limiting oxygen concentration (LOC) was investigated in the near-autoignition region using the same 5L apparatus; the findings are discussed with reference to an overpressurization incident in an air-liquid partial oxidation reactor. The general results are used to illustrate the application of LOC in partial oxidation processes subject to autoignition and to discuss elements of the current ASTM draft test method for LOC, which does not address test difficulties associated with condensable and/or reactive gas systems.
    Additional Material: 16 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. F3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 157-170 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Risk analysis in chemical process industries is an elaborate exercise involving several steps from preliminary hazard identification to development of credible accident scenarios, to preparation of strategies for prevention or control of damage.All this requires substantial inputs of time and money. In order to get an approximate yet workable assessment of risk at much lesser costs, indices have been developed which link typical findings of elaborate risk analysis to scales of risk. The scales, in turn, provide workable measures of hazards/risks/safety.In the past, indices have been reported for swift risk assessment - the noteworthy among them include Dow fire and explosion index, Mond fire, explosion and toxicity index, IFAL index, and mortality index. A few rapid ranking techniques have also been proposed.This paper presents a new system of methodologies for Hazard Identification and Ranking (HIRA). The system consists of two indices: one for fire and explosion hazards and another for the hazard due to likely release of toxic chemical. The magnitudes of these indices indicate the severity of the likely accident; in terms of the size of the impacted area.HIRA has been applied to a typical chemical process industry - a sulfolane plant - and its performance has been compared with that of the Dow's and the Mond's indices. The study reveals that HIRA is more sensitive and accurate than the other indices.
    Additional Material: 12 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 200-208 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 213-218 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: On October 31, 1987 a crane lifting a heat exchanger convection section failed and severed a 4″ loading line and a 2″ pressure relief line to an HF alkylation reactor settler drum at a petroleum refinery in Texas City, Texas. Vapors were emitted under pressure for about two hours and the vessel was plugged and drained aproximately 44 hours later. A plume from this accidental release passed through residential areas, damaging some vegetation (brown lawns), and spawning a class action law suit. An extensive analysis was conducted to determine the total inventory loss and to model the blowdown process and the concentrations of HF in the plume. Since the discharge rate was decreasing with time, a peak concentration of HF in the emitted vapors occurred just before the water spray mitigation system became fully operative. Consequently, the mitigation efforts were more effective late in the response when concentrations were already low. The predicted plume concentrations are consistent with observed vegetation damage effects, with concentrations below Emergency Response Planning Guideline Level 3 past 3/4 mile from the source. These results support a policy of sheltering in place during such an event.
    Additional Material: 8 Ill.
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  • 18
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fifty-five gallon steel drum of a liquid organic peroxide pressurized and ruptured in the mix room of a manufacturing plant. The head of the drum blew off and the ejected material ignited. The resulting fire was extinguished by the building sprinkler system and operating personnel. Although there were no injuries, the fire caused significant damage in the mix room. The investigation of this incident, its likely cause, and the corrective actions will be discussed.
    Additional Material: 9 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 238-242 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Brazoria County Petrochemical Council, 13 companies that are working together to enhance relations between industry and the community, united in a joint effort at complying with the EPA's Risk Management Program. One of the significant issues the group had to address was the need to develop meaningful hazard assessment for presentation to the public. The EPA's “Table Look-Up Approach” found in the Offsite Consequence Analysis Guidance document is certainly a good tool; however, the built-in conservatism results in over-estimates of potential hazard areas. Much more meaningful results are shown to be obtained using one of the hazard release models.The value of using a credible scenario with realistic meteorological data is demonstrated through the consistently smaller areas predicted by the PHAST Model for planning purposes. Realistic scenarios/failure modes and realistic model parameters are important so that the risk to the public is not overstated. Proprietary models such as PHAST are invaluable in providing more meaningful consequences for planning purposes.
    Additional Material: 2 Tab.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 263-271 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some of the hazards encountered by process plant operators involve the operation of in-line valves to control, start, and to stop flow. Torque required to operate valves may vary according to valve wheel size, in-line pressure, and valve flange position (open/closed). This study determined how valve wheel size, in-line pressure and valve position (open/closed) affect torque required to actuate a valve. Data were gathered with each combination of size, pressure and position for 336 valves in an operating petrochemical process facility. The results indicate that the main effects of valve wheel size, the in-line pressure, and open/closed valve position significantly affect operational torque requirements. In addition, the interaction between position and pressure was significant for operational torque. The implication of these results is that operators are exposed to operational torque requirements that exceed maximum acceptable capabilities that have been determined in previous studies.
    Additional Material: 12 Ill.
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 288-296 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An ammonia storage tank was built at the BASF Antwerp site in 1969 on land reclaimed from the sea. After several years of operation uneven foundation settlement, of up 2, occurred. In order to assure stability of this area for the next operation period (at least 10 years) measures were taken to ensure continued safe operation. One key measure was strain gauge monitoring at the location of maximum stress.
    Additional Material: 19 Ill.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 297-301 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Baker-Strehlow methodology was developed to provide an objective approach to prediction of blast pressures from vapor cloud explosions. The complete methodology was first published in 1994 [1]. Since then, it has evolved through ongoing research and use in VCE hazard analyses, facility siting studies and accident investigations. This article gives a brief overview of a paper on recent developments in the Baker-Strehlow methodology presented at the 31st Loss Prevention Symposium in Houston on March 9-13, 1997. Because the entire paper is too lengthy to be presented here, the following discussions may be lacking in some details. A copy of the complete paper can be obtained from the American Institute of Chemical Engineers (AIChE).Since the Baker-Strehlow method was first published, it has been used extensively in VCE hazard assessments in refineries and chemical plants. As expected, many practical lessons have been learned during the course of the hazard assessments, and the Baker-Strehlow method has evolved as a result. The changes have been evolutionary, not revolutionary. In keeping with the goals of the original study in which the methodology was developed, all changes have been incorporated with the intent of achieving an objective methodology to provide consistent prediction of VCE blast effects.The revisions to the Baker-Strehlow method resulting from experience gained during plant walk-downs and hazard assessments include: Systematic identification of “potential explosion sites” or “PESs,”Selection of the level of confinement for mixed zones of 2D and 3D confinement,Deciding on flame expansion when confinement is elevated above the vapor cloud,Selecting the reactivity for a fuel that is a mixture of fuels with differing reactivities,Predicting blast loads when there are multiple PES's within a vapor cloud considering different ignition source locations.
    Additional Material: 4 Ill.
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  • 23
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 83-85 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Safety, health and loss prevention are major areas of interst for the American Institute of Chemical Engineers (AIChE). There has been an evolution of these concerns over the years in the Institute just as it has in industry. This article chronicles this evolution.
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  • 24
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 25
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 1-8 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recent guidelines released by the U.S. EPA define a worst-case scenario as a release under stable atmospheric conditions defined as Pasquil-Gifford stability class F. Unfortunately, very few tests at F stability have been available heretofore to provide a basis for models. Recent test data with propane releases by the German research organization TUV provide a set of 60 experiments conducted specifically to define the effects of atmospheric stability class on dispersion. Of these, 25 tests were at F stability. A comparable number were at each other stability class A through E. In addition 23 tests were at wind speeds under 1.5 m/s in stable atmospheres. This paper reports on adjustments made to our models based on these new data by reducing the originally-postulated sensitivity to stability class. In spite of considerable scatter in the TUV data, particularly between two different types of propane analyzers, the model allows us to extract information by averaging over the tests.
    Additional Material: 15 Ill.
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  • 26
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 16-19 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A multi-disciplinary team developed a guideline for determining access restriction zones around vented solids handling equipment. The guideline provides a method for ensuring the discharge from a vented explosion will not cause injury to personnel. The steps in this method include: calculating the extent of external hazards from vented explosions; identifying potential areas where personnel could be exposed to a hazard; identifying ways to eliminate or reduce the hazard area; and establishing and documenting any access restrictions needed. Hazard zone calculations use the latest knowledge from research into fireball size, flame length and external pressure equations in VDI 3673. The guideline provides guidance for using this information. Options for mitigating or reducing external hazards from vented explosions are also described. As part of the project, the team audited several solids handling systems to look for potential oversights in existing restricted access areas. Some of the team's learnings from these audits are reviewed.
    Additional Material: 2 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 43-48 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper defines situation awareness (SA) and discusses its importance to operator-machine system safety and functioning in the context of process control activities. Specifically, identified are relationships of human detection of critical process cues converying the status of automated control systems and operator interpretation of the meaning and relevance of such information to the potential for negative incidents in chemical processing. Beyond individual operator SA in interacting with control systems, intra- and inter- work team SA are discussed for supporting individual attainment of process control responsibilities. Factors critical to team SA are discussed. “Road blocks” to team SA are also analytically examined. Lastly, methods for assessing individual and team SA are reviewed and vehicles for relating outcomes of these methods to changes in process control operator and team behavior to improve human-machine system safety and performance are relayed.
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  • 28
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    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    Process Safety Progress 17 (1998), S. 74-81 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The knowledge of the ingition behavior of dust-air mixtures due to electrical sparks (MIE, Minimum Ignition Energy) and hot surfaces (MIT, Minimum Ignition Temperature) is important for risk assessments in chemical production plants. The ignition behavior determines the extent and hence the cost of preventive protection measures.This paper describes the use of the minimum ignition energy and minimum ignition temperature as very important safety indexes in practice.Based on the latest results from large scale experiments on pneumatic filling of silos with polymeric materials and new results of full scale filling tests using Flexible Intermediate Bulk Containers (FIBC) manufactured from a variety of materials, guidance can be given to ensure safe operation in different situations such as filling, emptying operations, type of powder handled.The aim of this paper is to assist people dealing with product. It reflects the present state of the art and current knowledge of the assessment and measures associated with powder handling.
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    Process Safety Progress 17 (1998), S. 104-106 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In mid-1997, an Advanced Process Control (APC) scheme was implemented at a resins manufacturing complex with the goal of minimizing flare fuel gas usage while maintaining sufficient energy (BTU/SCF flare gas) to be in environmental regulatory compliance. Prior to APC implementation, the flare system was manually controlled by plant operators with minor attention paid to the minimization of fuel gas usage. Since implementation, APC has saved the plant thousands of dollars in fuel gas costs and reduced unnecessary combusted fuel gas emissions.Hazard analysis techniques were used in the development of the control scheme. An overview of the APC used, the economic evaluation, and the hazard analysis techniques used in the project are presented here.
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    Process Safety Progress 17 (1998), S. 107-123 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the risk assessment parlance, especially with reference to chemical process industries, the term “domino effect” is used to denote “chain of accidents,” or situations when a fire/explosion/missile/toxic load generated by an accident in one unit in an industry causes secondary and higher order accidents in other units. The multi-accident catastrophe which occurred in a refinery at Vishakhapatnam, India, on September 14, 1997, claiming 60 lives and causing damages to property worth over Rs 600 million, is the most recent example of the damage potential of domino effect.But, even as the domino effect has been documented since 1947, very little attention has been paid towards modeling this phenomena. In this paper we have provided a conceptual framework based on sets of appropriate models to forecast domino effects, and assess their likely magnitudes and adverse impacts, while conducting risk assessment in a chemical process industry. The utilizability of the framework has been illustrated with a case study.
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    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 33
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    Process Safety Progress 17 (1998), S. 149-154 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article deals with fire protection for water miscible flammable liquids stored in plastic containers packaged in boxes located on pallets. A series of fire tests was conducted with palletized rack storage arrangements using in-rack sprinkler protection at various levels. The intent of the paper is to present data from this test series for these types of commodities. The paper will identify various existing water miscible flammable liquid products stored in this fashion and provide background information for protecting this type of storage as it relates to NFPA 30 Flammable and Combustible Liquids Code. The test data indicates that further research work is needed in the area of plastic containers for use with the storage of combustible and flammable liquids. Included in the paper are discussions concerning possible protection strategies and suggestions for future research which would benefit those involved in risk management of this type of commodity.
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  • 34
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    Process Safety Progress 17 (1998), S. 176-183 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The safest method to prevent fires and explosions of flammable mixtures in the first place. This method requires detailed knowledge of the flammability region as a function of the fuel, oxygen, and nitrogen concentrations. A triangular flammability diagram is the most useful tool to display the flammability region, and to determine if a flammable mixture is present during plant operations.This paper describes how to draw and use a flammability diagram. A procedure to estimate the flammability region using the available and sometimes limited data is discussed. The paper also shows how to use the flammability diagram with plant operations involving inerting and purging, and from bringing vessels into and out of service. A compilation of flammability diagrams for 30 materials, based on previously published data is provided.An automated apparatus for acquiring data for a flammability diagram is described. The apparatus consists of a 20-L sphere with an automated gas mixing system, a fuse-wire ignition system, and a high speed pressure measurement and data acquisition system. Data derived from the apparatus includes flammability limits, maximum pressure during combustion, and the maximum pressure rate. The effect of fuse-wire ignitor dynamics on the results is studied. A flammability diagram for methane drawn from data obtained from the apparatus, is presented.
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    Process Safety Progress 17 (1998), S. 86-97 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Regulatory issues related to material safety have made the accurate measurement and/or prediction of flash points essential. The flash point is one of the major physical properties used to determine the fire and explosion hazards of a liquid. Flash points are used by virtually all governmental entities worldwide to define “flammable” and “combustible” materials for shipping and safety regulations.A model is described here for the calculation of closed cup flash points for multicomponent, single liquid phase, mixtures. The model is based upon rigorous vapor/liquid equilibrium calculations supplemented with information about the lower flammable limits (LFL's) and heats of combustion (ΔHc's) for the mixture's constituent components. The closed cup flash points predicted with this model are typically within ± 5°C of the experimentally reported values. Such a model is useful as a means of verifying experimental data and as a tool for screening product formulations prior to experimental flash point determination. The model should considerably enhance the safety evaluation portion of the product development cycle, thus leading to shortened product time-to-market cycles. While flash points calculated with this model are in excellent agreement with experiment, experimental determination is still encouraged for critìcal safety applications.
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    Process Safety Progress 17 (1998), S. 134-137 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: National Advisory Committee's Acute Exposure Guideline Levels (AEGLs) for ammonia are critically evaluated. The technical bases for concern about AEGL-2 and AEGL-3 values derived by the committee are summarized recommendations made.
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    Process Safety Progress 17 (1998), S. 127-133 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An explosion and flash fire in a fixed bed reactor occurred at a municipal wastewater treatment plant (WWTP). Two employees were injured in the accident. The accident occurred in an ozone treatment building where ozone was used to treat odors from the offgas of the sludge concentration units. Excess ozone manually was routed to the fixed bed reactor (ozone destruct unit) where the ozone is catalytically transformed into oxygen before being discharged to the atmosphere.An investigation of the accident was conducted to determine the root cause of the explosion and flash fire and identify corrective actions which the WWTP management could undertake to prevent a recurrence. This investigation included site inspections, interview with the injured employees, sampling and analysis of various materials, an explosion dynamics analysis, and a root cause analysis.It was concluded that cooling oil from one of the ozone generation units entered the main ozone gas line due to a crack in one of the reactor's dielectric tubes. The cooling oil was vented into the ozone destruct unit when an employee opened a ball valve on the main ozone gas line. The cooling oil, essentially a saturated hydrocarbon mixture, reacted exothermically when it contacted the manganese dioxide catalyst. The exothermic reaction resulted in an explosion which propelled the access panel outwards and dispersed the catalyst pellets. A flash fire followed the explosion. The flash fire burned two employees and caused thermal damage to a nearby control panel.Although this accident was the first of its kind at this facility, this was not the first time that the ozone generator had experienced a failure of a dielectric tube. Thus, there was a significant probability that a dielectric tube failure could leak cooling oil into the main ozone gas line. This failure event could, in turn, result in another explosion and flash fire. The WWTP staff neither designed nor fabricated the ozone generator-destructor system. Therefore, it did not seem appropriate for the WWTP staff to modify the ozone system. Instead, it was recommended that the ozone destruct unit be taken out of service. The WWTP management acted on this recommendation.
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    Process Safety Progress 17 (1998), S. 171-175 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An explosion occurred in a petroleum product storage tank at a refinery. The liquid petroleum product was a heavy oil used as an asphalt extender. There were no injuries, but the cleanup was costly. The storage tank was one of several which received the product stream from a dehydration unit. The accident occurred shortly after the refinery was brought back on-line following a shutdown for schduled maintenance.This was the first incident of this kind to occur at this facility. Analysis of the process data and eyewitness observations indicated that the dehydration tower, which was supposed to be maintained at a minimum of 100°C during the shutdown, was allowed to drift below 100°C for an unknown period of time. This deviation enabled liquid water to enter the storage tank. Three operational factors contributed to the accident. Corrective actions were recommended to prevent a recurrence of a similar incident.
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    Process Safety Progress 17 (1998), S. 184-189 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dust explosions have been with us for a long time. The first record of a dust explosion occurred in Turin, Italy, on December 14, 1785 [1]. The detailed record of this event is left to us by Count Morozzo. The event took place in Mr. Giacomelli's bakery. We know from his account that the weather was unseasonably dry, that a boy who worked in the bakery was using a shovel to stir and transfer the flour to a chute from a store room to the bakery and he had a lighted lamp to work by. The rest, as the saying goes, is history. No one was killed, and the building was saved by the sagacious fact of having plenty of windows. Since that first record, of course, there have been many explosions with much loss of life and significant economic consequences.
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    Process Safety Progress 17 (1998), S. 190-195 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The RSST DIERS vent sizing methodology is revised to provide realistic design equations for reactive systems consistent with available large-scale experience. Using easy to obtain RSST data such as rate of temperature rise and rate of pressure rise excellent agreement is illustrated for hybrid, vapor and gassy reactive systems.
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    Process Safety Progress 17 (1998), S. 196-199 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: From the 1960s onwards, the chemical and oil industries developed and used a number of new safety techniques which, in time, became second nature to those who applied them. They included the use of QRA for deciding priorities, Hazop and audits for identifying problems, inherently safer design for avoiding hazards, and more thorough investigation of incidents for identifying underlying causes. However, it has not yet become second nature to remember the accidents of the past and the actions needed to prevent them happening again.I joined industry in 1944 and moved to production in 1952. Then, and for at least 15 years afterwards, safety was a non-technical subject that could be left to arts graduates and elderly foremen. There was concern that people should not be hurt - great attention was paid to the lost-time accident rate - but there was no realization, that it was a subject worthy of systematic study by experienced technologists.This view changed at the end of the 1960s. A new generation of plants had been built, operating at higher temperatures and pressures and containing larger inventories of hazardous chemicals; the result was a series of fires and explosions and a worsening fatal accident rate. Figure 1 shows the situation in ICI, at the time the UK, s largest chemical company. Other companies experienced a similar state of affairs.As a result in 1968, I was appointed one of the company's first technical safety advisers, an unusual appointment at the time for someone with my experience, and if the reason for my appointment had not been so obvious I would have wondered what I had done wrong. I and my colleagues tried to apply the same sort of systematic thinking to safety that we applied in our other professional work. We developed some new concepts and techniques and adopted others. A common feature of our ides, realized only in restrospect, was that they consisted of more than mere problem-solving techniques. Once people had got used to these new concepts and used them a few times, they began to look at a whole range of problems in a different way.
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    Process Safety Progress 17 (1998), S. W3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 43
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    Process Safety Progress 17 (1998), S. 259-262 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Case histories of 65 incidents in runaway reactions and emergency relief in Taiwan were analyzed and classified into several categories according to their causes, materials involved, equipment types, reaction types, and ignition sources. The cases in reactors and storage tanks were examined in more detail owing to the higher probability or larger potential hazard in these two types of equipments. The most common consequence of the incidents are explosions, fires, and atmospheric release of toxic chemicals. The most severe case was a thermal explosion from an organic peroxide storage area which caused the death of 33 persons. Popping and direct releasing of process chemicals to the atmosphere from relieving devices cause the greatest environmental concerns to the community close to the plants. Runaway reactions in batch type reactors occur frequently due to various operational mistakes. Heat of reaction is the most frequent ignition source of runaway reactions and emergency relief.
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    Process Safety Progress 17 (1998), S. 272-277 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: EPA's Risk Management Program regulation, promulgated in June 1996 as 40 CFR Part 68 requires subject industries to submit Risk Management Plans by June 1999. This plan requires hazard assessment of the operations of a facility using worst case scenarios and alternative releases. EPA has provided an Off-site Consequence Analysis (OCA) guidance to help facilities in their hazard assessment.OxyChem will be significantly impacted by the RMP rule. This paper outlines OxyChem's general experience and its strategy in planning to comply with this rule. OxyChem's approach in the development of the scenarios required by the rule is described in this paper. Limitations involved in the use of EPA's look-up tables or a single modeling solution for conducting all of the OCA are discussed. A three tiered OCA approach is presented as a possible alternative.
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    Process Safety Progress 17 (1998), S. 209-212 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: HFC-227ea (CF3CHFCF3;1, 1, 1, 2, 3, 3, 3-heptafluoropropane) is an effective replacement for Halon 1301 in fire suppression systems, providing rapid extinguishment of flames through a combination of physical and chemical mechanisms. The vast majority of applications for HFC-227ea involve the protection of Class A hazards, which are characterized by low fuel loadings and low energy output, with fire sizes often in the range of 5-10 kW. Mid- and large-scale testing has demonstrated that HFC-227ea, at its minimum design concentration of 7.0% v/v, is effective at extinguishing fires typical of those expected to occur in electronic data processing (EDP) facilities, telecommunication facilities and anechoic chambers. The levels of HF produced following extinguishment of typical Class a fires with HFC-227ea were well below the estimated mammalian LC50 and the human Dangerous Toxic Load (DTL), and do not appear to present a threat to electronic equipment.
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    Process Safety Progress 17 (1998), S. 219-224 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sandia National Laboratories (Sandia) has refined a process for developing inherently safer system designs based on methods used by Sandia to design detonation safety into nuclear weapons. The process was created when Sandia realized that standard engineering practices did not provide the level of safety assurance necessary for nuclear weapon operations, with their potential for catastrophic accidents. A systematic approach, which relies on mutually supportive design principles integrated through fundamental physical principles, was developed to ensure a predictably safe system response under a variety of operational and accident-based stesses. Robust, safe system designs result from this thematic approach to safety, minimizing the number of safety critical features. This safety assurance process has two profound benefits: the process avoids the need to understand or limit the ultimate intensity of off-normal environments and it avoids the requirement to analyze and test a large array of accident environment scenarios (e.g., directional threats, sequencing of environments, time races, etc) to demonstrate conformance to all safety requirements.
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    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    Process Safety Progress 17 (1998), S. 233-237 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method is described to enhance the management of process safety risks such that the number and type of safety systems protecting against any hazard are consistently predicated upon risk. Further, that such an assignment of safety systems can be made consistent throughout an organization. This consistency is gained through standardization of qualitative risk ranking and by setting company guidelines.
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    Process Safety Progress 17 (1998), S. 243-258 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Research was carried out to develop improved protection guidelines for silane handling systems through enhanced understanding of the behavior of releases of this pyrophoric gas. The approach involved addressing three aspects of the problem: the prompt ignition behavior of silane; the reactivity characteristics of quiescent silane/air mixtures; and the rates of reaction of silane leaked into enclosures with and without explosion venting, in the presence of ventilation air flow. A first conclusion, reached from tests in a ventilated cabinet, was that, contrary to prevailing belief, the ventilation flow has no measurable effect on the prompt ignition of the release. From experiments in a 5.1-liter (311-in.3) sphere it was found that silane/air mixtures of concentrations between 1.4 and 4.1% (by volume) are explosive but stable. In this case, piloted ignition tests yielded laminar burning velocities up to 5 m/s (1000 ft/min). Mixtures between 4.5 and 38% (the maximum reached in the tests) were found to be metastable, and would undergo spontaneous ignition after a delay ranging from 15 to 120 seconds, with the shorter values corresponding to higher silane concentrations. Experiments were also performed in a 0.645-m3 (22.8-ft3) vessel both with and without explosion venting, to measure the rates of energy release associated with impulsively-started silane leaks from 1/8 and 1/4-in. (3.2 and 6.4-mm) lines. A method for the prediction of the venting requirements of partial-volume deflagrations (PVD) was evolved into a tool to quantify the pressure rise from ignition of silane leaks in enclosures. These results represent a significant step toward updating existing design recommendations which prescribe ventilation requirements that are based on outdated and, in some instances, misinterpreted data.
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    Process Safety Progress 17 (1998), S. 278-287 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gas explosion simulators are often used as tools in process plant design. This article presents some properties of gas explosions found using the EXSIM simulation software on three offshore modules with a total of nearly 10,000 simulations. The selected results are chosen for their supposed applicability to structural design in the process industries.Generalized data are presented for the effect of gas cloud size, explosion impulse vs. explosion pressure, pressure and impulse vs. duration, the probability of a “short” explosion, loading rate, pressure-time “shape” function, and the effect of introducing louvers.
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1940-1953 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Charge-Transfer Complexes of Tetrathiafulvalene (TTF) with 1,2,5-Thiadiazolequinones1)The syntheses and the X-ray structure analyses of the charge-transfer complexes of tetrathiafulvalene (TTF) with naphtho[2,3-c][1,2,5]thiadiazole-4,9-dione (1 : 2) (2) and benzol[1,2-c: 4,5-c′]-bis[1,2,5]thiadiazole-4,8-dione (1 : 1) (4) are reported. In their crystal structures both compounds are built up by mixed columnar stacks of donors and acceptors, forming a characteristic packing motive for organic D-A complexes with properties of an electrical insulator.
    Notes: Es wird über die Synthese und die Einkristallröntgenstrukturanalysen der Charge-Transfer-Komplexe von Tetrathiafulvalen mit Naphtho[2,3-c][1,2,5]thiadiazol-4,9-dion (1 : 2) (2) und Benzo-[1,2-c: 4,5-c′]bis[1,2,5]thiadiazol-4,8-dion (1 : 1) (4) berichtet. Beide Verbindungen weisen in ihrer Kristallstruktur aus Donoren und Acceptoren gemischte kolumnare Stapel auf, ein charakteristisches Packungsmotiv organischer D-A-Komplexe mit elektrischen Isolatoreigenschaften.
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1973-1976 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Generation of Nitrosyl Salts in Dry Organic MediaTrimethylsilyl halides (CH3)3SiX (2a - c, X = Cl, Br, I) are sufficiently electrophilic to cleave, in an equilibrium reaction, alkyl nitrites O = NOR (1a, b, R = i-C5H11, C2H5) with formation of O = NX (3a - c) and (CH3)3SiOR (4a, b). This reaction serves as a convenient in-situ-method to generate nitrosyl compounds NOX in chlorinated hydrocarbons as inert organic media.
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1954-1964 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Iminoboranes from the Thermal Decomposition of DialkylazidoboranesIminoboranes RB = NR (1a - f) are formed by the thermal decomposition of azidoboranes R2BN3 (5a - f) in the gas phase or in solution. At low temperature, the iminoboranes 1b, d, e (R = iPr, iBu, sBu) can be trapped from the gas phase. They are characterized and brought to reaction as isolated species. Without other reactands, the iminoboranes dimerize or trimerize to form the cyclic products 2 or 3, respectively, or polymerize to the wax-like solids 4. Produced in solution below 100 °C, the iminoboranes are azidoborated by the educts 5 to give the (azidoboryl)amines 6 which are transformed into the borazines 3 at 160 - 180 °C. Iminoboranes undergo an ethyloboration with BEt3, a cycloaddition with PhN3, and in the absence of the strongly reactive R2BN3 a concurring cycloaddition and azidosilation with Me3SiN3 with formation of 7 - 10, respectively.
    Notes: Iminoborane RB = NR (1a - f) entstehen beim thermischen Zerfall von Azidoboranen R2BN3 (5a - f) in der Gasphase oder in Lösung. Die aus der Gasphase abgeschiedenen Produkte 1b, d, e (R = iPr, iBu, sBu) lassen sich bei tiefer Temperatur isolieren, charakterisieren und isoliert umsetzen. Mit sich selbst reagieren die in der Gasphase ergzeugten Iminoborane 1a - f unter Cyclodi-oder -trimerisierung oder unter Polymerisierung zu Produkten von Typ 2, 3 bzw. 4. In Lösung unterhalb 100 °C erzeugt, werden die Iminoborane von den Edukten 5 zu Produkten 6 azidoboriert; diese lassen sich bei 160 - 180 °C in Borazine 3 überführen. Iminoborane erfahren durch BEt3 eine Ethyloborierung zu 7, mit PhN3 eine Cycloaddition zu 8 und mit Me3SiN3 nebeneinander eine Cycloaddition zu 9 und eine Azidosilierung zu 10, sofern nicht das Edukt R2BN3 zugegen ist, das dem Azid Me3SiN3 in der Reaktivität gegenüber 1 überlegen ist.
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  • 54
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1965-1972 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azodesilylation - a Novel Aprotic Diazotization TechniqueNitrosyl compounds NOA (4a - e, A = Cl, Br, BF4, CF3SO3, I) - generated partially in situ from O = N - OR/(CH3)3SiA (7a, b, R = i-C5H11, C2H5/8a, b, e, A = Cl, Br, I) - react in aprotic organic media with N,N-bissilylated organylamines RN[Si(CH3)3]2 (3b, R = C6H5; 15, R = CH3) under generation of diazonium systems R - N2+ A- and formation of non-nucleophilic hexamethyldisiloxane (6b). This method represents the first nucleophile excluding diazotization technique on the basis of three-coordinated nitrogen and is termed „azodesilylation“.
    Notes: Nitrosylverbindungen NOA (4a - e, A = Cl, Br, BF4, CF3SO3, I) - teilweise in situ hergestellt aus O = N - OR/(CH3)3SiA (7a, b, R = i-C5H11, C2H5/8a, b, e, A = Cl, Br, I) - reagieren mit N,N-bissilylierten Organylaminen RN[Si(CH3)3]2 (3b, R = C6H5; 15, R = CH3) in aprotischen organischen Medien unter Bildung von Diazonium-Systemen R - N2+ A- und nicht-nucleophilem Hexamethyldisiloxan (6b). Diese Methode repräsentiert die erste, Nucleophile ausschließende Diazotierungstechnik auf der Basis von 3fach koordiniertem Stickstoff und wird als „Azodesilylierung“ bezeichnet.
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  • 55
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1977-1979 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Säurekatalysierte Cyclisierung des En-Produkts aus α-Pinen und PTADAluminiumchlorid-katalysierte Reaktion des En-Produkts 2 aus 4-Phenyl-4H-1,2,4-triazol-3,5-dion (PTAD) und α-Pinen (1), des 1-(6,6-Dimelthyl-2-methylenbicyclo[3.1.1]hept-3-yl)-4-phenyl-1,2,4-triazolidin-3,5-dions, ergab 3,8,8-Trimelthyl-N-phenyl-4,5-diazatricyclo[4.2.1.03,7]nonan-4,5-dicarboxamid (6) in 78% Ausbeute. Auch Bortrifluorid-etherat, trockener Chlorwasserstoff und p-Toluolsulfonsäure katalysieren die Cyclisierung von 2 zu 6, aber nicht in diesem Maße. Der Mechanismus der Cyclisierung wird über eine Gerüstumlagerung der Carbenium-Ionen-Zwischenstufen gedeutet.
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  • 56
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1980-1981 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chain Lengthening of Tetrafluoro-1,2-ethanedisulfenyl Dichloride by the Reaction with Hydrogen PeroxideThe reaction of the little compound ClSCF2CF2SCl (1) with aqueous H2O2 results in the formation of ClS2CF2CF2SSCF2CF2SO2Cl(2), which is characterized on the basis of 19F NMR, mass, IR, and Raman spectroscopy.
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  • 57
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1982-1986 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fluorination of Adamantane Derivatives with Oxygen DifluorideFluorination of adamantane and adamantane derivatives 1 with OF2 in the absence of an HF-trap gives fluoroadamantanes 2 and adamantanols 3 in varying amounts. Increasing yields of 2 are obtained in the presence of Na2CO3 as an HF-trap. In addition, the fluorooxahomoadamantanes 4b and e are formed in this reaction. The fluorination of adamantanone (5) with OF2 leads to analogous products.
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  • 58
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1987-1990 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoelektronenspektren einiger Reduktionsprodukte von [2.2]ParacyclophanAnhand des He(I)-Photoelektronen(PE)-Spektrums von 2,3′,5,6′-Tetrahydro[2.2]paracyclophan (2) wird gezeigt, daß die Through-Bond-Wechselwirkung zwischen den Sechsringen klein, innerhalb der Cyclohexadienringe aber groß ist. Über die PE-Spektren der weiteren Hydrierungsprodukte 3 und 4 wird berichtet.
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  • 59
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1991-1993 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses with Cyclobutadienes, 51). 5,5,6,6-Tetracyano-5,6-dihydro-Dewar benzene/3,3,4,4-Tetracyano-3,4-dihydrobenzvalene - a Novel Equilibrating SystemThe cyclobutadiene 3 reacts with tetracyanoethylene to give a 1 : 1-mixture of the dihydro-Dewar benzene 5 and the dihydrobenzvalene 6, which can be separated by crystallisation. In deuteriochloroform solution 5 and 6 are in a 1 : 1 equilibrium.
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  • 60
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 61
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 2275-2286 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Electron Rich Heterocycles as Donor Groups in Fluorescent DyesThe synthesis of N-methylphthalimides substituted with the donor groups pyrazole, triazole, benzotriazole, and naphthotriazole in position 4 is described (17, 18, 14, 12). The substituent constants of these groups are obtained by alkaline hydrolysis of the corresponding phthalimide dyes. Their solvatochromism in absorption and fluorescence gives information about charge distribution in ground- and excited state.
    Notes: Die Darstellung von N-Methylphtalimiden wird beschrieben, die in 4-Stellung die Donorgruppen Pyrazol, Triazol, Benzotriazol und Naphthotriazol tragen (17, 18, 14, 12). über die alkalische Hydrolyse des Imids werden die Substituentenkonstanten der Reste bestimmt. Die Solvatochromie in Absorption und Fluoreszenz gibt Information über die Ladungsverteilung in Grund- und angeregtem Zustand.
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  • 62
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Arene(phosphane)metal Complexes, IV1). Synthesis of (6-Phosphonio-η5-cyclohexadienyl)ruthenium(II) Compounds and their Conversion into Dicationic (Benzene)ruthenium(II) Complexes[C6H6Ru(PR3)(PR3′)PR3″]2+The complexes [C6H6RuCl(PR3)PR3′]PF6 (1 - 4) and [C6H6RuCl2(PR3)] (9, 10) react with phosphanes PR3″ in the presence of NH4PF6 to give the (6-phosphonio-η5-cyclohexadienyl)ruthenium(II) compounds [(6-R3″P-η5-C6H6)Ru(PR3)(PR3′)PR3″](PF6)2 (5 - 8 11). Similarly, from [C6H6Ru(CH3CN)3](PF6)2 (12) and PMe3 the complex [(6-Me3P-η5-C6H6)Ru(PMe3)2CH3CN](PF6)2 (13) is formed. The IR and NMR spectra of 5 - 8, 11, and 13 indicate that the phosphonio group is in the exo-position at the sp3 carbon atom of the cyclohexadienyl ligand. Below - 30°C, rotation around the metal-ring bond is so hindered that rigid conformers are detected. Compounds 5 - 8 react with trifluoroacetic acid with elimination of the phosphonio group to yield the PF6 salts of the half-sandwich type complexes [C6H6Ru(PR3)(PR3′)PR3″]2+ (14 - 17).
    Notes: Die Komplexe [C6H6RuCl(PR3)PR3)]PF6 (1 - 4) und [C6H6RuCl2(PR3)] (9, 10) reagieren mit Phosphanen PR3″ in Gegenwart von NH4PF4 zu den (6-Phosphonio-η5-cyclohexadienyl)-ruthenium(II)-Verbindungen [(6-R3″P-η5-C6H6)Ru(PR3)(PR3″](PF6)2 (5 - 8, 11). Aus [C6H6Ru(CH3CN)3](PF6)2 (12) und PMe3 erhält man analog den Komplex (6-Me3P-η5-C6H6)Ru(PMe3)2CH3CN](PF6)2 (13). Die IR- und NMR-Spektren von 5 - 8, 11 und 13 weisen darauf hin, daß sich die Phosphoniogruppierung in der exo-Position am sp3-C-Atom des Cyclohexadienylliganden befindet. Unterhalb - 30°C ist die Rotation um die Metall-Ring-Bindung so stark behindert, daß starre Konformere nachweisbar sind. Die Verbindungen 5 - 8 reagieren mit Trifluoressigsäure unter Abspaltung der Phosphoniogruppe zu den PF6-Salzen der Halbsandwich-Komplexe [C6H6Ru(PR3)(PR3′)PR3″]2+ (14 - 17).
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  • 63
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Arene(phosphane)metal Complexes, VI1). Synthesis of [(RC6H5)OsI(PMe3)2]PF6 from (exo-6-RC6H6)OsI(PMe3)2: A contribution to the Mechanism of Aromatization of Substituted Cyclohexadienyl Ligands by „endo-H Abstraction“The compounds (exo-6-RC6H6)OsI(PMe3)2 (2 - 5, 7) react smoothly with [CPh3]PF6 in acetone to give the (arene)osmium(II) complexes [(RC6H5)OsI(PMe3)2]PF6 (8 - 12) in quantitative yield. The hydride elimination proceeds via two (cyclohexadienyl)hydridoosmium(IV) intermediates (13 and 14, 15, respectively) which can be prepared from 2, 5, 6 (R = CH3, n-C4H9, t-C4H9) and CF3CO2H/NH4PF6. The (cyclohexadienyl)hydrido complexes [(RC6H6)Os(H)I(PMe3)2]+ undergo an intramolecular isomerization which leads to a cation possessing a CH2 group in the six-membered ring. This cationic complex or (more probably) the neutral compound (2- or 3-RC6H6)OsI(PMe3)2 formed on deprotonation reacts with [CPh3]+ by abstraction of an exo-hydrogen atom.
    Notes: Die Verbindungen (exo-6-RC6H6)OsI(PMe3)2 (2 - 5, 7) reagieren mit [CPh3]PF6 in Aceton rasch und quantitativ zu den (Aromaten)osmium(II)-Komplexen [(RC6H5)OsI(PMe3)2]PF6 (8 - 12). Die Hydrid-Eliminierung verläuft über zwei (Cyclohexadienyl)hydridoosmium(IV)-Zwischenstufen (13 bzw. 14, 15), die aus 2, 5, 6 (R = CH3, n-C4H9, t-C4H9) und CF3CO2H/NH4PF6 synthetisiert werden können. Die (Cyclohexadienyl)hydrido-Komplexe [(RC6H6)Os(H)I(PMe3)2]+ gehen eine intramolekulare Isomerisierung ein, wobei ein Kation mit einer CH2-Gruppe im Sechsring entsteht. Dieses Komplexkation oder (wahrscheinlicher) die nach Deprotonierung erhaltene Neutralverbindung (2- bzw. 3-RC6H6)OsI(PMe3)2 reagiert mit [CPh3]+ unter Abstraktion eines exo-H-Atoms.
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  • 64
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Arene(phosphane)metal Complexes, V1). On the Addition of Carbanions to (Benzene)ruthenium(II) and -osmium(II) Complexes. The Crystal and Molecular Structure of (exo-6-n-C4H9-η5-C6H6)OsI(PMe3)2The complex [C6H6RuCl(PMe3)2]PF6 (1) reacts with methyllithium to give a mixture of products that contains (η5-C6H6CH3)RuCH3(PMe3)2 (2) as the main component. From 1 and LiC6H5/LiBr the bromide 3 is primarily formed but the final product is (η5-C6H6C6)H5RuC6H5(PMe3)2 (4). Reaction of [C6H6OsI(PMe3)2]PF6 (5) with organyllithium compounds LiR (R = CH3, C2H5, n-C3H7, n-C4H9, t-C4H9, C6H5) yields the complexes (η5-C6H6R)OsI(PMe3)2 (6 - 11). 31P NMR spectra of 6 - 11 indicate restricted rotation at low temperatures around the metal-ring axis. According to X-ray structure analysis of 9 (R = n-C4H9) the cyclohexadienyl ring possesses an envelope conformation. The n-butyl group occupies the exo-position at the sp3-C atom.
    Notes: Der Komplex [C6H6RuCl(PMe3)2]PF6 (1) reagiert mit Methyllithium zu einem Produktgemisch, welches (η5-C6H6CH3)RuCH3(PMe3)2 (2) als Hauptkomponente enthält. Aus 1 und LiC6H5/LiBr entsteht über 3 bei längeren Reaktionszeiten (η5-C6H6C6H5)RuC6H5(PMe3)2 (4). Die Umsetzung von [C6H6OsI(PMe3)2]PF6 (5) mit Organyllithium-Verbindungen LiR (R = CH3, C2H5, n-C3H7, n-C4H9, t-C4H9, C6H5 ergibt die Komplexe (η5-C6H6R)OsI(PMe3)2 (6 - 11), in denen nach den 31P-NMR-Spektren die Rotation um die Metall-Ring-Bindung bei tiefen Temperaturen stark eingeschränkt ist. Die Röntgenstrukturanalyse von 9 (R = n-C4H9) beweist die „Envelope“-Konformation des Cyclohexadienylrings. Die n-Butylgruppe befindet sich in der exo-Position am sp3-C-Atom.
    Additional Material: 1 Ill.
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  • 65
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 172-186 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radical Ions, 55. The One-Electron Oxidation of Tetrahedrane to Cyclobutadiene Radical CationTetra-tert-butyltetrahedrane, on one-electron oxidation using AlCl3 in CH2Cl2, opens to form tetra-tert-butylcyclobutadiene radical cation, which can also be generated under identical reaction conditions from tetra-tert-butylcyclobutadiene itself. The assignments of the ESR and ENDOR spectra are supported by deutero substitution of one tert-butyl group and by MNDO hypersurfaces for the thermal and for the oxidative structural changes of both C4 skeletons. The feasible formation of a valence isomeric tert-butyl(tri-tert-butylcyclopropenyl)carbene radical cation is discussed.
    Notes: Tetra-tert-butyltetrahedran öffnet sich bei Einelektronen-Oxidation mit AlCl3 in CH2Cl2 zum Tetra-tert-butylcyclobutadien-Radikalkation, das unter gleichen Reaktionsbedingungen auch aus Tetra-tert-butylcyclobutadien erzeugt werden kann. Die Zuordnungen der ESR- und ENDOR-Spektren werden durch Deutero-Substitution einer tert-Butyl-Gruppe sowie durch MNDO-Hyperflächen für die thermischen und oxidativen Strukturänderungen der beiden C4-Gerüste gestützt. Die mögliche Bildung eines valenzisomeren tert-Butyl(tri-tert-butylcyclopropenyl)carben-Radikalkations wird diskutiert.
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  • 66
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 948-954 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Acidic Complexones Bearing Donor-enhancing Pyridine Anchour GroupsThe synthesis, complex stability and -selectivity for alkaline earth metal ions of 2,6-pyridinebis-(methylamine)-N, N, N′, N′-tetraacetic acid (3a) and of their donor-enforced analogues 3b, c are described. The acid dissociation constants and the stability constants of the metal complexes have been measured potentiometrically at 25°C in water of constants ionic strength (μ = 0.1). The stability order is Ca 〉 Mg 〉 Sr 〉 Ba which is analogues to the selectivity of EDTA and comparable aliphatic complexones. The magnitudes of the stability constants of 3a are comparable to those of EDTA, while the donor-enforced analogues 3b, c form less stable complexes with alkaline earth metal ions.
    Notes: Synthese, Komplexstabilität und -selektivität gegenüber Erdalkalimetall-Ionen von 2,6-Pyridinbis(methylamin)-N, N, N′, N′-tetraessigsäure (3a) und ihren Donor-verstäkten Analoga 3b, c werden beschrieben. Die Bestimmung der Dissoziations- und Komplexbildungskonstanten erfolgt potentionmetrisch bei 25°C in Wasser konstanter ionaler Stärke (μ = 0.1). Die Bildungskonstanten der Metallkomplexe nehmen in der Reihenfolge Ca 〉 Mg 〉 Sr 〉 Ba ab und folgen damit der bei EDTA und vergleichbaren aliphatischen Komplexonen vorgefundenen Selektivität. 3a weist mit EDTA vergleichbare hohe Komplexbildungskonstanten auf, während die Donor-verstärkten Analoga 3b, c schwächere Erdalkalimetallkomplexe bilden.
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  • 67
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 959-965 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and X-Ray Structure Analysis of the Diels-Alder Adduct of 4-Phenyl-4H-1,2,4-triazole-3,5-dione with OctavaleneIn the reaction of 4-phenyl-4H-1,2,4-triazole-3,5-dione with octavalene (1) the Diels-Alder adduct 2 is formed. From its X-ray structure analysis the dihedral angle for the bicyclo[1.1.0]butane group, the 2- and 4-positions of which are spanned by four atoms, has been determined to be 122.7°. The bridging bond C1 - C3 has a length of 1.487 Å.
    Notes: Aus Octavalen (1) und 4-Phenyl-4H-1,2,4-triazol-3,5-dion bildet sich das Diels-Alder-Addukt 2. Seine Röntgenstrukturanalyse ergab für das Bicyclo[1.1.0]butan-Gerüst, dessen 2- und 4-Stellung durch vier Atome überbrückt sind, einen Interplanarwinkel von 122.7°. Die Brückenbindung C1 - C3 hat eine Länge von 1.487 Å.
    Additional Material: 3 Ill.
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  • 68
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensed Ring Systems, XV. About the Reaction of α-Chloro Sulfoxides with Potassium tert-Butoxide by the Example of the Synthesis of OxapropellenesThe synthesis of dithia- 1a - 3a and oxathiapropellenes 1b - 3b is described. From 1b - 3b the α-chloro sulfoxides 4 - 6 and α-chloro sulfones 4a - 6a are prepared, or which in most cases several stereoisomeric racemates are obtained. The constitution, configuration, and conformation of the α-chloro sulfoxide 4, the main product obtained from 1b, was elucidated by X-ray structure analysis. Only in that way it was possible to deduce the constitutions and configurations of the other stereoisomeric α-chloro sulfoxides 4 - 6 and α-chloro sulfones 4a - 6a, respectively, using 13C NMR spectroscopy. By the reaction of the α-chloro sulfones 4a - 6a with potassium tert-butoxide (Ramberg-Bäcklund reaction) the corresponding oxapropellenes 7 - 9 are obtained only in low yields (〈 10%). Contrary, the α-chloro sulfoxides 4 - 6, und analogous conditions give yields of 80 - 90% (from 4, 6) and 25% (from 5).
    Notes: Es wird die Synthese der Dithia- 1a - 3a und Oxathiapropellene 1b - 3b beschrieben. Aus 1b - 3b werden die α-Chlorsulfoxide 4 - 6 und α-Chlorsulfone 4a - 6a hergestellt, von denen meist mehrere stereoisomere Racemate erhalten werden. Konstitution, Konfiguration und Konformation des Hauptprodukts der aus 1b erhaltenen α-Chlorsulfoxide 4 wurden durch Röntgenstrukturanalyse ermittelt. Erst dadurch wurde es möglich, mit Hilfe der 13C-NMR-Spektroskopie die Konstitutionen und Konfigurationen der anderen stereoisomeren α-Chlorsulfoxide 4 - 6 und α-Chlorsulfone 4a - 6a aufzuklären. Bei der Reaktion der α-Chlorsulfone 4a - 6a mit Kalium-tert-butylat (Ramberg-Bäcklund-Reaktion) erhält man die entsprechenden Oxapropellene 7 - 9 nur in geringer Ausbeute (〈 10%), während die α-Chlorsulfoxide 4 - 6 unter analogen Bedingungen Ausbeuten von 80 - 90% (aus 4, 6) und 25% (aus 5) ergeben.
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 982-989 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Selectivity of the Reaction of Carbocations with NucleophilesThe problem of the selectivity of the nucleophilic attack on carbocations according to the HSAB-principle is discussed in relation to the solvolysis in ether of 7,7-bis(trifluoromethylsulfonyloxy)-norbornane (2) and 7,7-bis(trifluoromethylsulfonyloxy)-2-norbornene (4) in presence of dimethyl-magnesium, magnesium iodide and methylmagnesium iodide. The nucleophiles and carbocations are arranged according to the hard-soft-scale, so our results can be explained.
    Notes: Das Problem der Selektivität beim nucleophilen Angriff an Carbokationen wird im Rahmen des HSAB-Prinzips am Beispiel der Solvolysen in Ether von 7,7-Bis(trifluormethylsulfonyloxy)norbornan (2) und 7,7-Bis(trifluormethylsulfonyloxy)-2-norbornen (4) in Anwesenheit von Dimethylmagnesium, Magnesiumiodid und Methylmagnesiumiodid erörtert. Die Nucleophile und die als Zwischenstufen auftretenden Carbokationen werden auf der Hart-weich-Skala eingeordnet, wobei die Ergebnisse erklärt werden können.
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  • 70
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1003-1012 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dichloropalladium(II) Complexes with α-Amino Acids, α-Amino Acid Esters, Dipeptides, and Dipeptide EstersA series of trans-dichloropalladium(II) complexes Cl2PdL2 (L = α-amino acid, α-amino acid ester, dipeptide, dipeptide esters) and cis-Cl2Pd(histidine) has been prepared and spectroscopically characterized. The X-ray structure of trans-Cl2Pd(GlyOEt)2 (3b) has been determined.
    Notes: Eine Reihe von trans-Dichloropalladium(II)-Komplexen Cl2PdL2 mit (L = α-Aminosäure, α-Aminosäureester, Dipeptid, Dipeptidester) sowie cis-Cl2Pd(Histidin) wurde dargestellt und spektroskopisch charakterisiert. Die Röntgenstruktur von trans-Cl2Pd(GlyOEt)2 (3b) wurde bestimmt.
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  • 71
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1436-1454 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Evidence for a Radical Chain Mechanism for the Knabe Reaction of 1,2-Dihydro-2-methylpapaverineA free radical chain mechanism is proposed for the Knabe reaction and the accompanying elimination reaction on account of their nonintegral reaction order and of successful inhibition experiments. 3,4-Dimethoxybenzyl radicals are the chain carrying species. Battersby's synthesis of N-methylpavine (19) from 1,2-dihydro-2-methylpapaverine (9) is dependent on the presence of formic acid as radical chain inhibitor. In the presence of inhibitors 1-benzyl-1,4-dihydro-2-methyl-isoquinolinium ions like 10 are persistent species whose chemistry can now be investigated.
    Notes: Die Knabe-Reaktion von 1,2-Dihydro-2-methylpapaverin (9) und die begleitende Eliminierungsreaktion wurden durch ihre gebrochene Reaktionsordnung und durch die Möglichkeit der Inhibition als Radikalkettenreaktionen erkannt, deren kettentragendes Radikal das 3,4-Dimethoxybenzylradikal ist. Die Synthese von N-Methylpavin (19) aus 1,2-Dihydro-2-methylpapaverin (9) ist an die Anwesenheit von Ameisensäure als Inhibitor der Radikalketten gebunden. Durch Zusatz von Inhibitoren können nun Immoniumionen 10 und analoge Verbindungen stabilisiert und ihre Chemie untersucht werden.
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  • 72
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1455-1464 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azo Bridges from Azines, III. Unexpected Formation of a Compounds with Parallel C=C and N=N Bonds2)Dialdehyde 5 reacts with hydrazine at pH 〉 7 to form the trimeric azine 6Tr, at pH 〈 4, however, to yield unexpectedly 8, which contains parallel C=C and N=N bonds in close proximity. The complex reaction is clarified. 8 is characterized by structure proving reactions and its spectroscopic data.
    Notes: Der Dialdehyd 5 reagiert mit Hydrazin bei pH 〉 7 zu dem trimeren Azin 6Tr, bei pH 〈 4 unerwartet zu 8, das parallel benachbarte C=C- und N=N-Bindungen besitzt. Der komplexe Reaktionsverlauf wird aufgeklärt. 8 wird durch struktursichernde Reaktionen und spektroskopische Daten charakterisiert.
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  • 73
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1465-1475 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azo Bridges from Azines, IV1). Intramolecular [2 + 2] Photocycloaddition of Parallel C=C and N=N BondsThe parallel C=C and N=N bonds in the rigid molecules 1 - 10 photocyclize nearly quantitatively, forming 1,2-diazetidines 11 - 20. Their structure is confirmed by spectroscopic methods and for 13 by X-ray analysis. Radiation induced denitrogenation, the normal reaction for similar compounds without neighbouring C=C bonds, is suppressed even with the sensitive derivatives of 2,3-diazabicyclo[2.2.1]heptene. Photocyclization of 6, carrying two neighbouring C=C bonds, includes only the norbornene bond.
    Notes: In den starren Molekülen 1 - 10 reagieren die benachbarten parallelen C=C- und N=N-Bindungen nahezu quantitativ unter Photocyclisierung zu den 1,2-Diazetidinen 11 - 20, deren Struktur spektroskopisch und für 13 durch Kristallstrukturanalyse bewiesen wird. Die in Abwesenheit der C=C-Bindung beobachtete Photo-Denitrogenierung unterbleibt selbst bei den empfindlichen Derivaten des 2,3-Diazabicyclo[2.2.1]heptens. Photocyclisierung von 6 mit zwei zur N=N-Bindung benachbarten C=C-Bindungen tritt nur mit der Norbornendoppelbindung ein.
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  • 74
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1497-1512 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amino Acids, 21,2). N-Acetyl α,β-Didehydro α-Amino Acid Esters from α-Azidocarboxylic Acid Esters and Acetic Anhydride by Nitrogen Elimination with Rhenium Catalystsα-Azidocarboxylic acid esters 2 react with acetic anhydride in presence of catalytic amounts of rhenium heptasulfide and - if necessary - by addition of hydrochloric acid to give N-acetyl 3 or/and N,N-diacetyl-α,β-didehydro-α-amino acids esters 4 in very good yields. Exclusively monoacetylated products 3 are formed if water ist added before work up.
    Notes: Beim Erwärmen von α-Azidocarbonsäureestern 2 in Acetanhydrid/Essigsäure in Gegenwart katalytischer Mengen Rheniumheptasulfid und gegebenenfalls unter Zugabe von Chlorwasserstoff entstehen in sehr guten Ausbeuten N-Acetyl- 3 und/oder N,N-Diacetyl-α-β-didehydro-α-amino-säureester 4. Durch Zugabe von Wasser vor der Aufarbeitung erfolgt partielle Deacetylierung unter ausschließlicher Bildung der N-Monoacetylverbindungen 3.
    Additional Material: 7 Tab.
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  • 75
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amino Acids, 31). N-Acetylated α-β-Didehydro α-Amino Acid Derivatives by Nitrogen Elimination from α-Azido-carboxylic Acid Amides and α-Azido-ω-aminocarboxylic Acid Lactams with Rhenium Catalystsα-Azidocarboxylic acid amides 2 and α-azido-ω-aminocarboxylic acid lactams 6, respectively, react with acetic anhydride in the presence of rhenium catalysts by nitrogen eliminations to give N-acetyl- 7 and N,N-diacetyl-α,β-didehydro-α-amino acid amides 8, α-acetylamino- 11 and α-diacetylamino-α,β-didehydro-ω-aminocarboxylic acid lactams 12, respectively. Reactions of the educts 6c, d - with a ring size 7 or 8 - additionally lead to the oxazoloazepine 14c and the oxazoloazocine 14d, respectively.
    Notes: Bei der Umsetzung von α-Azidocarbonsäureamiden 2 mit Acetanhydrid in Gegenwart von Rheniumkatalysatoren entstehen unter Stickstoffabspaltung N-Acetyl- 7 und N,N-Diacetyl-α,β-didehydro-α-aminosäureamide 8, bei der von α-Azido-ω-aminocarbonsäurelactamen 6 α-Acetyl-amino- 11 und α-Diacetylamino-α,β-didehydro-ω-aminocarbonsäurelactamen 12, wobei sich aus den Verbindungen 6c, d, mit der Ringgliederzahl 7 bzw. 8 außerdem noch das Oxazoloazepin 14c bzw. das Oxazoloazocin 14d bilden.
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  • 76
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Phosphorus, 131. Synthesis and Properties of the Methylenediphosphiranes (t-BuP)2)C = CR2 (R = H, Me, 4-ClC6H4)The first methylenediphosphiranes (diphosphamethylenecyclopropanes) (t-BuP)2C = CH2 (1), (t-BuP)2C = CMe2 (2), and (t-BuP)2C = C(4-ClC6H4)2 (3) were synthesized by [2 + 1] cyclocondensation of K(t-Bu)P - P(t-Bu)K with the corresponding 1,1-dichloroolefins. The homocyclophosphanes (t-BuP)n (n = 4,3) and in the case of 1 mainly H(t-Bu)P - P(t-Bu)H are formed as by-products. The three-membered heterocycles 2 and 3 could be purely isolated as surprisingly stable compounds. According to an X-ray single-crystal analysis 3 possesses approximately C2 symmetry and exhibits one of the smallest bonding angles ψ (P - P - C) = 52.4° on a phosphorus atom experimentally proved so far. Along [100] there are canals filled with disordered n-pentane molecules.
    Notes: Die ersten Methylendiphosphirane (Diphosphamethylencyclopropane) (t-BuP)2C = CH2 (1), (t-BuP)2C = CMe2 (2) und (t-BuP)2C = C(4-ClC6H4)2 (3) wurden durch [2 + 1]-Cyclokondensation von K(t-Bu)P - P(t-Bu)K mit den entsprechenden 1,1-Dichlorolefinen synthetisiert. Als Nebenprodukte entstehen die Homocyclophosphane (t-BuP)n (n = 4,3) und im Fall von 1 vor allem H(t-Bu)P - P(t-Bu)H. Die Dreiringheterocyclen 2 und 3 konnten als thermisch überraschend beständige Verbindungen in reiner Form isoliert werden. 3 besitzt nach der Röntgenstrukturanalyse annähernd die Symmetrie C2 und enthält mit ψ (P - P - C) = 52.4° einen der kleinsten experimentell gesicherten Bindungswinkel am Phosphor. Längs [100] liegen fehlgeordnet mit n-Pentan gefüllte Kanäle vor.
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  • 77
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1523-1541 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminierung, III. Trimethylsilanol als austretende Gruppe, V. Silylierung-Aminierung von Hydroxy-N-heterocyclenDurch Silylierung-Aminierung lassen sich Hydroxy-N-heterocyclen (z. B. 18, 21, 26 u. a.) bequem in einer Einstufen-Eintopfreaktion aminieren (→ 20, 23 - 25 etc.). Aromatische Hydroxy-N-heterocyclen werden durch Silylierung in aktivierte und lipophile Zwischenprodukte vom Typ 3, 8 umgewandelt, die sich in situ mit Ammoniak, primären oder sekundären Aminen zu den entsprechenden mono-, bis- und tris-aminierten Produkten (5, 10) umsetzen. Die Additions-Eliminierungsreaktion von Aminen an O-silylierte Heterocyclen ist Lewissäure-katalysiert und verläuft gewöhnlich in hohen Ausbeuten, falls die austretende Gruppe Trimethylsilanol in situ durch überschüssiges Silylierungsmittel in Hexamethyldisiloxan umgewandelt wird. Anwendungsbreite und Grenzen dieser einfachen Methode werden diskutiert.
    Notes: Hydroxy N-heterocycles such as 18, 21, 26, and others are efficiently aminated in a one-step/one-pot procedure by silylation-amination to give 20, 23 - 25 etc. Silylation converts aromatic hydroxy N-heterocycles into activated and lipophilic intermediates of type 3, 8 which react in situ with ammonia, primary or secondary amines to form the corresponding mono-, bis- or tris-aminated products (5, 10). This addition-elimination of amines to O-silylated heterocycles in Lewis acid-catalyzed and proceeds usually in high yields if the leaving group trimethylsilanol is converted in situ by excess silylated agent into hexamethyldisiloxane. Scope and limitations of this simple procedure are discussed.
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  • 78
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1572-1582 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Benzonitrile as a 6-Electron Donor Ligand: The Clusters Fe3(CO)9(μ3(η2)-NCC6H5) and Fe4(CO)12(μ4(η2)-NCC6H5)The reaction of Fe3(CO)12 with benzonitrile in the presence of hydrogen leads to the benzonitrile complexes Fe3(CO)9(μ3(η2)-NCC6H5) (1a) and Fe4(CO)12(μ4(η2)-NCC6H5) (2). Their structures were determined crystallographically. The benzonitrile ligand is coordinated to the iron atoms formally via on „s̰-bond“ and two „π-bonds“ in 1a, and via three s̰-bonds and one π-bond in 2.
    Notes: Die Reaktion von Fe3(CO)12 mit Benzonitril in Anwesenheit von Wasserstoff führt zu den beiden Benzonitril-Komplexen Fe3(CO)9(μ3(μ2)-NCC6H5) (1a) und Fe4(CO)12(μ4(η2)-NCC6H5) (2). Ihre Strukturen wurden kristallographisch aufgeklärt. Der Benzonitril-Ligand ist in 1a formal über eine „s̰-Bindung“ und zwei „π-Bindungen“, in 2 über drei s̰-Bindungen und eine π-Bindung an die Eisenatome koordiniert.
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  • 79
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Spin-Spin Coupling Constants by Platinium-195 as Criteria for a Configuration Determination in Platinum Organic CompoundsThe platinum organic compounds [Pt(η4-1,5-cyclooctadiene)(XC6H4)2] and cis-[Pt(P(n-Bu)3)2-(XC6H4)2] (X = H, 4-CH3, 4-(CH3)3C, 4-(CH3)2N, 3-F, 4-F, 4-CH3O, 4-CF3; 3a - 4, cis-4a - h) as well as trans-[Pt(P(n-Bu)3)2(4-CH3OC6H4)2] (trans-4g) and trans-[Pt(P(n-Bu)3)2(4-CF3C6H4)2] (trans-4h) have been studied by 31P-, 13C-, and 1H NMR spectroscopy. The coupling constants 1J[195Pt, 31P], nJ[195Pt, 13C], nJ[195Pt, H], and 2J[31P, 13C] show a clear correlation to the ligand configuration at the dsp2-hybridized platinum and can therefore be used as basis for configuration determination.
    Notes: Die platin-organischen Verbindungen [Pt(η4-1,5-cyclooctadien)(XC6H4)2] und cis-[Pt(P(n-Bu)3)2-(XC6H4)] (X = H, 4-CH3, 4-(CH3)3C, 4-(CH3)2N, 3-F, 4-F, 4-CH3O, 4-CF3; 3a - h, cis-4a - h) sowie trans-[Pt(P(n-Bu)3)2(4-CH3OC6H4)2] (trans-4g) und trans-[Pt(P(n-Bu)3)2(4-CF3C6H4)2] (trans-4h) wurden 31P-, 13C- und 1-NMR-spektroskopisch untersucht. Die Kopplungskonstanten 1J[195Pt, 31P], nJ[195Pt, 13C], nJ[195Pt, H] und 2J[31P, 13C] zeigen eine eindeutige Abhängigkeit von der Konfiguration der Liganden am dsp2-hybridisierten Platin; sie können daher zur sicheren Konfigurations-Bestimmung verwendet werden.
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  • 80
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1597-1605 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Structure of N-Methylenecarboxamides: X-Ray Data, Spectroscopy, and Quantum Mechanical CalculationsN-(Diphenylmethylene)acetamide (1) has been studied by X-ray crystallography as an example for the polyfunctional, highly reactive N-methyleneamides. The dihedral angle (C = N - C = O = 73°) and the bond lengths indicate that there is only little interaction between the C = O and the C = N groups. Extensive ab initio 3-21G calculations for the parent molecule H2C = N - CH = O (2) predict a C - N rotational barrier of ca. 4 kcal/mol with a cisoid form (C = N - C = O = 23°) as the most stable structure. MNDO data as well as spectroscopic properties (IR, 13C NMR) suggest high molecular flexibility due to the many electronic interactions possible for the nitrogen atom.
    Notes: Als Beispiel für die polyfunktionellen N-Methylencarbonsäureamide wurde N-(Diphenylmethylen)acetamid (1) röntgenographisch untersucht. C = N - C = O-Torsionswinkel (73°) und Bindungslängen deuten auf nur geringe Wechselwirkungen zwischen C = O- und C = N-Molekülteil. Ausführliche ab initio-3-21G-Berechnungen am Grundsystem H2C = N - CH = O (2) sagen eine C - N-Rotationsbarriere von ca. 4 kcal/mol voraus, wobei als stabilste Struktur eine cisoide Form (C = N - C = O-Winkel = 23°) gefunden wurde. MNDO-Daten und spektroskopische Untersuchungen (IR, 13C-NMR) deuten ebenfalls auf hohe molekulare Beweglichkeit, die vor allem durch die vielfältigen elektronischen Wechselwirkungsmöglichkeiten des Stickstoffatoms verursacht wird.
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  • 81
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1659-1670 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reduction of β-Lactams, I. Reduction of 3,3,3′,3′-Tetramethyl[1,1′-biazetidine]-2,2′-dione with Complex HydridesReduction of the title compound 7 with lithium aluminium hydride leads to four products 8 to 11 in yields depending on the reaction conditions. Compounds 8 to 10 are also obtained from the bicyclic hydrazide 12, isomeric with 7. Therefore, the reduction of 7 and 12 is likely to proceed in part via common intermediates. A reaction scheme is proposed to account for the generation of the products. With other hydride reagents complex reaction mixtures are obtained from 7. The reduction of 7 to 3,3,3′,3′-tetramethyl-1,1′-biazetidine (13) failed.
    Notes: Die Reduktion der Titelverbindung 7 mit Lithiumaluminiumhydrid liefert die vier Produkte 8 - 11 in von den Reaktionsbedingungen abhängigen Mengenverhältnissen. Da die Verbindungen 8 - 10 auch aus dem mit 7 isomeren bicyclischen Hydrazid 12 erhalten werden, muß die Reduktion von 7 und 12 z. T. einheitlich ablaufen. Hierfür wird ein Reaktionsschema vorgeschlagen. Mit anderen Hydridübertragungsreagenizen entstehen aus 7 komplexe Produktgemische. Die Reduktion von 7 zu 3,3,3′,3′-Tetramethyl-1,1′-biazetidin (13) gelang nicht.
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 565-574 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of (Trimethylstannyl)adamantane DerivativesReaction of brominated adamantane compounds with (trimethylstannyl)lithium afforded a series of (trimethylstannyl)adamantane derivatives. Additionally, we found products from fragmentation and reduction reactions which allowed conclusions concerning the mechanisms. Surprisingly high stereoselectivities were observed in most instances. By Wurtz synthesis we obtained 2-adamantyltriphenylstannane.
    Notes: Die Umsetzung bromierter Adamantanverbindungen mit (Trimethylstannyl)lithium lieferte eine Reihe von (Trimethylstannyl)adamantan-Derivaten. Wir fanden zusätzlich Fragmentierungs- und Reduktionsprodukte, die Rückschlüsse auf den Mechanismus zuließen. Überraschend ist die hohe Stereoselektivität der meisten Reaktionen. Durch Wurtz-Synthese wurde auch 2-Adamantyltriphenylstannan erhalten.
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  • 83
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 575-584 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Influence of Substituents on the Valence-tautomeric Equilibrium of 4,8-Substituted HomotropilidenesThe valence-tautomeric equilibrium of 4,8-substituted homotropilidenes 2 - 4 is governed by electronic (preference of a substituent for attachment to a cyclopropyl or an aliphatic carbon atom) and steric factors. The conformational change chair → boat, which precedes the Cope rearrangement of a homotropilidene, cannot take place when both endo-8- and cis-4-substituents are present.
    Notes: Das Valenzgleichgewicht 4,8-substituierter Homotropilidene 2 - 4 wird durch elektronische (Präferenz eines Substituenten für Cyclopropyl- oder aliphatische Verknüpfung) und sterische Faktoren bestimmt. Die der Cope-Umlagerung vorgeschaltete Konformationsänderung Sessel → Boot wird verhindert, wenn das Homotropiliden sowohl in endo-8- wie in cis-4-Stellung substituiert ist.
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  • 84
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic β-Enamino Esters, 311). Novel 6:7-, 6:8, and 5:6:7-Combinations of Heterocondensed Pyrimidines from Iminophosphoranes of Heterocyclic β-Enamino Esters. - Stable Heterocyclic YlidesWith acetylenic esters the (5-azolylimino)triphenylphosphoranes 10a - d do not show any cyclo-addition tendency, while the (2-thienylimino)triphenylphosphoranes 8a, b yield the stable ylids 13a, b. By treatment with phenyl isocyanate the iminophosphoranes 16a - m, 17, and 18a, b afford the carbodiimides 19a - m, 20, and 21a, b; however, 10b - d give the O-ethylisoureas 24b - d. 19a, b, e, f, h are transformed in aqueous ethanol into 6:7-bicycles, namely into oxepino[2,3-d]pyrimidines 25a, b, e, f, h. With isopropylamine the 2-isopropylamino-6:7-bicycles 31a - c, e - h are formed analogously, while in the case of thiocin 21a the 6:8-bicycle 34 is obtained. The salts 33f, g are formed by treating 19f, g or 25f with aqueous diethylamine. Accordingly, 2-aminoethanol, 3-aminopropanol, and ethylenediamine react with 19a, b, f, l to afford the 2-hydroxy- and 2-aminoalkyl-6:7-bicycles 36a - f; by treatment with hydrazine the 2-hydrazinooxepino- and -thiepino[2,3-d]pyrimidines 38a - h and 39 are obtained, which are converted with functional C1-units into 5:6:7-tricycles 43a - d, 45'a, b.
    Notes: Die (5-Azolylimino)triphenylphosphorane 10a - d zeigen mit Acetylendicarbonsäureestern keine Tendenz zur Cycloaddition, während die (2-Thienylimino)triphenylphosphorane 8a, b, zu den stabilen Yliden 13a, b reagieren. Mit Phenylisocyanat ergeben die Iminophosphorane 16a - m, 17 und 18a, b die Carbodiimide 19a - m, 20 und 21a, b; 10b - d liefern statt dessen die O-Ethylisoharnstoffe 24b - d. In wäßrigem Ethanol werden 19a, b, e, f, h in 6:7-Bicyclen, nämlich in die Oxepino[2,3-d]pyrimidine 25a, b, e, f, h umgewandelt. Mit Isopropylamin bilden sich die 2-Isopropylamino-6:7-Bicyclen 31a - c, e - h und im Fall des Thiocins 21a der 6:8-Bicyclus 34. Die Salze 33f, g entstehen durch Einwirkung von wäßrigem Diethylamin auf 19f, g bzw. auf 25f. 2-Aminoethanol, 3-Aminopropanol und Ethylendiamin ergeben mit 19a, b, f. l analog die 2-Hydroxy- und 2-Aminoalkyl-6:7-Bicyclen 36a - f; mit Hydrazin werden die 2-Hydrazinooxepino- und -thiepino[2,3-d]pyrimidine 38a - h und 39 erhalten, die mit funktionellen C1-Bausteinen zu den 5:6:7-Tricyclen 43a - d, 45'a, b führen.
    Additional Material: 24 Tab.
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  • 85
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 682-693 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Addition of Aldehydes to Activated Double Bonds, XXXIV1). Addition of Aldehydes to Cyclic α-Methylene KetonesThe thiazolium salt-catalyzed addition of aldehydes to the cyclic α-methylene ketones 3, 4, 7, 8, 48, and 49 leads to γ-diketones 9 - 22, 50 - 53; some of them were converted into unsaturated ketones 23 - 28, pyrroles 29 - 34, 37 - 43, and furans 35, 36, 44 - 46. The α-methylene ketones were synthesized by retro Diels-Alder reaction of the corresponding norbornene compounds 1, 2, 5, 6, 47.
    Notes: Die Thiazoliumsalz-katalysierte Addition von Aldehyden an die cyclischen α-Methylenketone 3, 4, 7, 8, 48 und 49 führt zu γ-Diketonen 9 - 22, 50 - 53, aus denen einige ungesättigte Ketone 23 - 28, Pyrrol- 29 - 34, 37 - 43 und Furanderivate 35, 36, 44 - 46 synthetisiert wurden. Die Darstellung der α-Methylenketone erfolgte durch Retrospaltung entsprechender Norbornenderivate 1, 2, 5, 6 und 47.
    Additional Material: 7 Tab.
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  • 86
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 694-701 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diazadiene als Steuerliganden in der Katalyse, 51). Synthese chiraler Diazadiene R* - N = CR' - CR' = N - R*Die im Prinzip einfache Kondensationsreaktion von Glyoxal (als Hydrat) und 2,3-Butandion mit primären Aminen führt leider bei aliphatischen Aminen mit tertiärem bzw. sekundärem α-Kohlenstoff oftmals zu unerwünschten Additionsprodukten. Unter speziellen Synthesebedingungen können mit (R)-1-Phenylethylamin (1) und (1S,2S,3S,5R)-3-(Aminomethyl)pinan die gewünschten Diimine (Diazadiene (dad): R* - N = CR' - CR' = N - R*, R' = H, CH3) 4, 6 - 8 erhalten werden. Aus (S)-2-Amino-1-butanol (3) werden je nach Dion-Komponente ein Morpholinomorpholin 9 bzw. ein Bioxazolidin 10 gebildet, die von elektronenreichen Metallen in ihrer isomeren Form als Diazadiene gebunden werden ((dad)Mo(CO)4 11 und 12). Die offenkettige dad-Form ist durch O-Silylierung (14, 15) stabilisierbar. Die (dad)Eisen(0)-katalysierte Dimerisierung von Butadien zu 4-Vinyl-1-cyclohexen mit diesen dad-Liganden ergibt Enantiomerenüberschüsse e.e. bis zu 16%.
    Notes: The condensation of glyoxal (as hydrate) or 2,3-butanedione with primary amines is, in principle, a simple reaction. Unfortunately, aliphatic amines with secondary or tertiary α-carbons often give unwanted addition products. Under special reaction conditions the desired diimines (diazadienes (dad): R* - N = CR' - CR' = N - R*, R' = H, CH3) 4, and 6 - 8 are obtained from (R-1-phenyl-ethylamine (1) and (1S,2S,3S,5R)-3-(aminomethyl)pinane (2). Depending on the dione, a morpholinomorpholine 9 and a bioxazolidine 10 are formed from (S)-2-amino-1-butanol (3), which are bound by electron-rich metals in their isomeric dad form ((dad)Mo(CO)4 11 and 12). The acyclic dad structure is stabilized by O-silylation (14, 15). The (dad)iron(0) catalyzed dimerization of butadiene with these controlling ligands to 4-vinyl-1-cyclohexene occurs with an enantiomeric excess up to 16%.
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  • 87
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Application of High-Resolution Solid State NMR Spectroscopy for the Determination of the Ring-Chain TautomerismThe structure of the benzaldehyde derivatives 1 and 2 showing ring-chain tautomerism was investigated by NMR spectroscopy in the solid state and in solution. Difficulties in preparing single crystals, low solubility, and the presence of solvent in the crystal prevent an X-ray analysis and other spectroscopic methods. The structural problem was solved by C-13 CP-MAS NMR spectroscopy. 2-[2-(Methylamino)ethyl]-3-nitrobenzaldoxime (1) exists in the chain form in the crystal but is in equilibrium with the cyclic isomer in solution. Two different types of crystals were obtained from the aminoethenylbenzaldehyde derivative 2, one of them containing the chain the other the cyclic form of 2. Signal assignments in the solid state result from comparison with the spectra in solution, which have been partially assigned by 2D 1H 13C NMR shift correlation.
    Notes: Die Struktur der Benzaldehyd-Derivate 1 und 2, die Ring-Ketten-Tautomerie zeigen, wird durch NMR-Spektroskopie im festen und gelösten Zustand untersucht. Schwierigkeiten beim Züchten von Einkristallen sowie die Schwerlöslichkeit bzw. die Anwesenheit von Kristallösungsmittel verhinderten die Anwendung der Röntgenstrukturanalyse und anderer spektroskopischer Methoden. Mit Hilfe von C-13-CP-MAS-NMR-Spektren wird das Strukturproblem lösbar. In 2-[2-(Methyl-amino)ethyl]-3-nitrobenzaldoxim (1) liegt im Kristall die offene Form vor, die in Lösung mit dem cyclischen Tautomeren 1b im Gleichgewicht steht. Vom Aminoethenylbenzaldehyd-Derivat 2 lassen sich zwei verschiedene Kristalle gewinnen, in denen alternativ die offene und die cyclische Struktur vorliegt. Zur Signalzuordnung werden die Festkörper-NMR-Spektren mit den z. T. durch 2D-1H-13C-NMR-Verschiebungskorrelation zugeordneten C-13-Spektren verglichen.
    Additional Material: 2 Ill.
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  • 88
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 710-724 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Catalyses, 121). New Optically Active P,N Ligands and Their Use in Rh-Catalyzed Asymmetric Hydrogenation and HydrosilylationNew P,N-ligands 2, 4 and 5 were prepared by Schiff base condensation of (2-formylphenyl)diphenyl- and tris(2-formylphenyl)phosphane with (R)-(+)-1-phenylethylamine and ethylenediamine. (R)-(+)-aminphos (6) was obtained by hydrogenation of the C = N bond in (R)-(+)-iminphos (2). The new imine ligands form stable chelate complexes. The pseudotetrahedral CpFe(CO)[R)-(+)-iminphos]PF6 was separated into the diastereoisomes with respect to the Fe configuration. The square planar Rh[(R)-(+)-iminphos]2X is obtained as a cis/trans mixture. The isolated Rh complexes and the combinations [Rh(COD)Cl]2/2, 4, and 6, respectively, were used as catalysts for the homogeneous hydrogenation of (Z)-α-(acetylamino)cinnamic acid and for the hydrosilylation of acetophenone with diphenysilane. The optical yield of 1-phenyl-ethanol, the product of hydrolysis of the hydrosilylation, increases with increasing ligand excess, decreasing catalyst concentration, and decreasing temperature.
    Notes: Neue P,N-Liganden 2, 4 und 5 wurden durch Schiffbasenkondensation von (2-Formylphenyl)diphenyl- und Tris(2-formylphenyl)phosphan mit (R)-(+)-1-Phenylethylamin und Ethylendiamin dargestellt. (R)-(+)-aminphos (6) wurde durch Hydrierung der C = N-Bindung in (R)-(+)-iminphos (2) erhalten. Die neuen Imin-Liganden bilden stabile Chelatkomplexe. Das pseudotetraedrische CpFe(CO)[(R)-(+)-iminphos]PF6 wurde in die Diastereomeren bezüglich der Fe-Konfiguration getrennt. Das quadratisch-planare Rh[(R)-(+)-iminphos]2X fällt als cis/trans-Gemisch an. Die isolierten Rh-Komplexe und die Kombinationen [Rh(COD)Cl]2/ 2, 4 bzw. 6 wurden als Katalysatoren für die homogene Hydrierung von (Z)-α-(Acetylamino)zimtsäure und für die Hydrosilylierung von Acetophenon mit Diphenylsilan eingesetzt. Die optische Ausbeute an 1-Phenylethanol, dem Hydrolyseprodukt der Hydrosilylierung, steigt mit zunehmendem Ligandenüberschuß, mit abnehmender Katalysatorkonzentration und mit abnehmender Temperatur.
    Additional Material: 2 Ill.
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  • 89
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 3021-3033 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Solvolysis of (Z)/(E)-1-Methyl-2-[2-(1-propyn-1-yl)phenyl]vinyl Triflate and 1-Methylene-2-[2-(1-propyn-1-yl)phenyl]ethyl TriflateThe synthesis and solvolysis of the triflates (Z)/(E)-8 and 20 in various solvents are described. The (E)-triflate 8 reacts in trifluoroethanol by rearrangement via the intermediate naphthyl cation 9 to give the naphthyl ether 22 and the naphthyl triflate 24. The identification of 1-bromo-2,3-dimethylnaphthalene (26) after addition of bromide ions to the solvolysis confirms 9 as a reactive intermediate. The (Z)-triflate 8 solvolyses preferably to the elimination product 28, the formation of [(3-methyl-2-naphthyl)methyl] (trifluoroethyl) ether (23), however, can not be explained via the cation 9 as an intermediate. The solvolysis of the triflate 20 leads also to the rearranged products 22 and 23.
    Notes: Die Synthese und Solvolyse der Triflate (Z)/(E)-8 und 20 in verschiedenen Lösungsmitteln wird beschrieben. Das (E)-Triflat 8 reagiert in Trifluorethanol bevorzugt unter Umlagerung über das intermediäre Naphthylkation 9 zum Naphthylether 22 und zum Naphthyltriflat 24. Der Nachweis von 1-Brom-2,3-dimethylnaphthalin (26) nach Bromidionenzusatz zur Solvolyse bestätigt 9 als reaktive Zwischenstufe. Das (Z)-Triflat 8 solvolysiert bevorzugt zum Eliminierungsprodukt 28, die Bildung des [(3-Methyl-2-naphthyl)methyl]-(trifluorethyl)-ethers (23) kann jedoch nicht über das Kation 9 als Zwischenstufe erklärt werden. Die Solvolyse des Triflates 20 führt ebenfalls zu den Umlagerungsprodukten 22 und 23.
    Additional Material: 1 Tab.
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  • 90
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 3160-3164 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurement of Absolute Rates of Radical Additions to Alkenes by the “Mercury Method”Using the 5-hexenyl radical (2) as “radical clock” the rates of radical additions to methyl acrylate (5a) and acrylonitrile (5b) are measured by the “mercury method” (Table 1). Alkyl radicals are trapped by the alkylmercury hydride 1 with rate constants of at least 107 1 · mol-1 · s-1.
    Additional Material: 2 Tab.
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  • 91
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    Berichte der deutschen chemischen Gesellschaft 117 (1984) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 92
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 3175-3182 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radical Chain Reactions with Maleic Anhydrides  -  Contrathermodynamic StereoselectivityThe reactions of cyclohexylmercuric chloride with NaBH4 and alkenes 1a-g yield 60-84% of products 3, 4 and 6 in a radical chain process (table 1). Caused by steric effects of substituents Z at least 97% of the radical attack occurs at the unsubstituted carbon atom of maleic anhydrides 1c-g. Only fluoromaleic anhydride 1b is attacked by cyclohexyl radicals predominantly at the substituted carbon atom, because fluorine is a tiny, electron releasing substituent. Radicals 2 are trapped predominantly from the anti-direction by the H-donor (figure 1), yielding cis-compounds 3 as main products. This „contrathermodynamic“ stereoselectivity ranges between 2.3 and 19 (table 1).
    Notes: Die Reaktion von Cyclohexylquecksilberchlorid mit NaBH4 und den Alkenen 1a-g liefert in einer Radikalkettenreaktion die Produkte 3, 4 und 6 in 60- bis 84proz. Ausbeuten (s. Tab. 1). Wegen der sterischen Effekte der Substituenten Z erfolgt der Angriff der Radikale zu mindestens 97% am unsubstituierten C-Atom der Maleinsäureanhydride 1c-g. Allein das Fluormaleinsäureanhydrid 1b wird bevorzugt am substituierten C-Atom durch Cyclohexyl-Radikale angegriffen. Die Ursache für diese umgekehrte Regioselektivität liegt in der geringen Raumerfüllung und dem elektronenspendenden Effekt des Fluoratoms. Die H-Übertragung auf die Radikale 2 erfolgt überwiegend von der anti-Seite (s. Abb. 1), so daß die thermodynamisch instabileren cis-Verbindungen 3 als Hauptprodukte entstehen. Diese „kontrathermodynamische“ Stereoselektivität liegt zwischen 2.3 und 19 (s. Tab. 1).
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  • 93
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1241-1245 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactive Platinum Complexes with α-Amino Acid Derivatives and their 31P- and 15N Nuclear Magnetic Resonance SpectraThe α-amino acidate chelate complexes (n-Bu3P)(Cl)⊓PtNH2CH(R)COO (1a - c) (R = H, CH3, CHMe2) react with thionyl chloride, phosphorus pentachloride, or acetyl chloride by cleavage of the chelate ring to give complexes with α-amino acyl chloride or acetic glycine anhydride as ligands: (n-Bu3P)Cl2Pt(NH2CH2COCl) (2), (n-Bu3P)Cl4Pt(NH2CH(CHMe2)COCl) (6), (n-Bu3P)-Cl2Pt(NH2CH2CO(O)OCCH3) (4). Using 15N enriched amino acids, the IR, 15N and 31P NMR spectra indicate cis orientation of phosphane and amino groups in all these complexes.
    Additional Material: 3 Tab.
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  • 94
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1246-1249 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses with Alkenediazonium Salts, III. ω,ω′-Di-1H-1,2,3-triazolylalkanes from Ethenediazonium Hexachloroantimonates and ω,ω′-DiaminoalkanesReaction of the ethenediazonium hexachloroantimonates 2 with ω,ω′-diaminoalkanes 3 leads to ω,ω′-di-1H-1,2,3-triazolylalkanes 5.
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  • 95
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1222-1234 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Boron, 1351). Addition Compounds of 1,3,2-Diazaborolidines with Aluminium and Gallium Halides1,3-Dimethyl-1,3,2-diazaborolidines 3 - 6 add aluminium and gallium halides, respectively, in a 1 : 1 molar ratio. The ligand is monodentate in these coordination compounds (3a - e, 4a, 5a, b, 6a). Addition occurs at one of the ring nitrogen atoms irrespective of the B-substituent. A consequence of this coordination is a long BN bond to the chiral tetracoordinated nitrogen atom as well as a considerable shortening of the BN bond involving the tricoordinate ring nitrogen. In addition, the almost planar five-membered ring adopts the envelope conformation as shown by an X-ray structure analysis of 5a. In contrast, the 2-(dimethylamino)diazaborolidine 7 yields unstable 1 : 1 besides stable 1 : 2 adducts 8. In these the Lewis acid is also coordinated to the ring nitrogen atoms only.
    Notes: Die 1,3-Dimethyl-1,3,2-diazaborolidine 3 - 6 addieren Aluminium- oder Galliumhalogenide im Molverhältnis 1 : 1 zu Koordinationsverbindungen 3a - e, 4a, 5a, b, 6a, in denen der Ligand einzähnig ist. Die Anlagerung erfolgt unabhängig vom B-Substituenten an einem Ringstickstoff-Atom. Folge dieser Koordination ist die Ausbildung einer langen BN-Bindung zum chiralen tetra-koordinierten Ring-Stickstoff, eine erhebliche Verkürzung der BN-Bindung zum dreifach koordinierten endocyclischen Stickstoffatom und der Übergang des nahezu planaren Fünfrings in die „envelope“-Konformation, wie die Röntgenstrukturanalyse von 5a belegt. Im Gegensatz dazu liefert das 2-(Dimethylamino)diazaborolidin 7 mit AlX3 und GaX3 instabile 1 : 1- und stabile 1 : 2-Addukte 8. In diesen ist die Lewis-Säure nur an den Ringstickstoff-Atomen koordiniert.
    Additional Material: 3 Ill.
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  • 96
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1250-1254 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Simple Synthesis of Primary Amines via their N,N-Bis(trimethylsilyl) DerivativesPrimary halogen compounds 1 or the corresponding tosylates react with sodium bis(trimethylsilyl)amide (2) in hexamethyldisilazine to form N,N-bis(trimethylsilyl)amines 3, which are converted into the amine hydrochlorides 5 by treatment with aqueous HCl.
    Additional Material: 1 Tab.
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  • 97
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1255-1258 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dibenz[a,j]anthracen durch Photocyclodehydrierung von 9,10-Dihydro-2-styrylphenanthrenWährend aus 2-Styrylphenanthren (1) durch Photocyclodehydrierung Benzo[c]chrysen (2) entsteht, läßt sich unter Ausnutzung der „ΣF*-Regel“5) aus 9,10-Dihydro-2-styrylphenanthren (4) durch Photocyclodehydrierung zu 6 und anschließende Dehydrierung Dibenz[a,j]anthracen (3) erhalten.
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  • 98
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    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1259-1261 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Simple Synthesis of 5-Cyano-2-pyridinecarboxylic Acid and its AmideThe title compounds 3 and 2 (X = CN) are prepared in good yields by regioselective carbamoylation of 3-cyanopyridine in a Minisci reaction and by consecutive amide hydrolysis with amyl nitrite in HCl-saturated acetic acid. The observed regioselectivity apparently remains confined to carbamoyl and possibly acyl radicals and to - M-effect substituents in 3-position.
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  • 99
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    Berichte der deutschen chemischen Gesellschaft 117 (1984) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Berichte der deutschen chemischen Gesellschaft 117 (1984) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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