Library

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 12 (1973), S. 119-126 
    ISSN: 0570-0833
    Keywords: Heterocycles ; Intramolecular reactions ; Acylation ; Nitrile hydrogen halide adducts ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five-membered, six-membered, and seven-membered aza-, diaza-, and thiazaheterocycles can be prepared by cyclization of. ω-cyano carboxylic acid halides in the presence of hydrogen halides in aprotic solvents. Nitrile-hydrogen halide adducts occur as intermediates in this novel heterocycle synthesis of wide application. The acylating cyclizations of nitriles in protonic media, which proceed via imidic esters or amides, are not discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0570-0833
    Keywords: Analytical methods ; Fibers ; Polymers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analytical characterization of synthetic fibers has not kept pace with their development and production. Whereas the “second-generation” fibers have already conquered the market, the chemical investigation methods used until now for the three classical fiber polymers of the polyester, polyamide, and polyacrylonitrile types are still frequently unsatisfactory. Though they satisfy the requirements of production supervision and quality control, they do not supply enough information to enable us to understand and to explain the degradation of and damage to the polymers under hydrolytic, thermal, or thermooxidative influences. This report presents methods of chemical analysis that open up new possibilities for investigations of this nature on synthetic fibers. The results reported for commercial products must not be taken as an assessment of quality. They are simply intended to show the diversity to be expected in the chemical properties and to emphasize the practical basis of the chemical analysis of synthetic fibers.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 11 (1972), S. 751-760 
    ISSN: 0570-0833
    Keywords: Inorganic fibers ; Fibers ; Materials science ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This progress report ends with the sentence: In the opinion of many experts, we are entering an “age of inorganic fibers”. An attempt is made in the article to outline the present stage of development and the outlook for one of the most interesting fields of modern materials science.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0570-0833
    Keywords: Conformation analysis ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This review deals with the following aspects of conformational analysis in saturated heterocyclic systems: 1. Conformational equilibria in 2-aryl and 2-ethynyl-1,3-dioxanes in various solvents. 2. The generalized anomeric effect in perhydro-1,3-diazines and its origin. 3. Unexpected conformational equilibria in 5-heterosubstituted 1,3-dioxanes. 4. Normal and anomalous solvent effects in conformational equilibria of 1,3-dioxanes with heteroatoms at C-5. Calculation of solvent effects. Correlation of ΔG0 as a function of solvent with solvatochromic transition energy ET (30); a new scale of “solvent polarity”. 5. Interplay of hydrogen bonding with dipolar, non-bonded and eclipsing interactions in 5-hydroxymethyl- 1,3-dioxanes. 6. Highly stereoselective H-D exchanges in anancomeric 1,3-dithianes. 7. Potential distortion of a cyclohexane or 1,3-dioxane ring by a tert-butyl substituent. Evidence from 1H-NMR and 13C-NMR investigations and from X-ray structure analysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 11 (1972), S. 949-963 
    ISSN: 0570-0833
    Keywords: Cyanic esters ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of cyanic esters with acylating agents and the reactions of the resulting N-acyliminocarbonic ester halides are surveyed, and syntheses of heterocycles with cyanic esters and their reaction products are then reported.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 10 (1971), S. 20-33 
    ISSN: 0570-0833
    Keywords: Hetarynes ; Heterocycles ; Alkynes ; Arynes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During recent years, instead of concentrating on the detection of the intermediacy of new hetarynes, as they did between 1958 and 1964, workers in this field have been more concerned with the critical sifting and checking of the earlier work. Special interest has been shown in the relation between structure and reactivity in the hetarynes. It has been shown that in addition to the elimination-addition mechanism (EA; hetaryne intermediate), other reaction paths (anomalous addition-elimination mechanism [AEa] and “Reinecke mechanism”) are possible for nucleophilic cine-substitutions on hetaryl halides. The use of deuterated hetaryl halides has proved very valuable for the elucidation of the mechanism of nucleophilic substitutions. Even where substitution mechanisms are superimposed on one another the occurrence of a hetaryne intermediate can be detected by a technique known as the “base competition method”. A five-membered hetaryne (4,5-didehydro-1-methylimidazole) has been detected for the first time by this method with a probability that borders on certainty. Selectivity determinations have shown that the replacement of a CH group in 1,2-didehydrobenzene and in 1,2-didehydronaphthalene by an N atom distinctly increases the reactivity to bases. According to EHT (Extended Hückel Theory) calculations, the as yet hypothetical 2,3-didehydropyridine is richer in energy than 3,4-didehydropyridine, this agrees more closely with the experimental findings than the opposite result obtained from simple MO calculations. Besides cine-substitution (1,2 shift), tele-substitution (1,3-shift) has also been observed on reaction of hetaryl halides (pyridine, quinoline, and pyrimidine systems) with bases. An EA mechanism (via m-didehydrohetarenes) and an AEa mechanism are considered as alternatives for the tele-substitution.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 10 (1971), S. 11-20 
    ISSN: 0570-0833
    Keywords: Valence isomerization ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Valence isomerization and the phenomenologically related principle of valence tautomerism, as they apply to several nitrogen-containing heterocyclic systems, are discussed herein. Attention is called first to 1H-azepines and the reluctance of such substances to isomerize to azanorcaradienes. The role of homo-1H-azepines in this context is then briefly outlined. Azocines (azacyclooctatetraenes) are seen to occupy an interesting position in the sense that pronounced shifts in the position of equilibrium (from almost entirely monocyclic to virtually completely bicyclic) occur with substitutional alterations of various types. The capability of azabullvalenes for degenerate valence isomerization is the next presented, and contrast is made with the properties of benzazabullvalenes and an azasemibullvalene derivative.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 333-341 
    ISSN: 0570-0833
    Keywords: Strained molecules ; Heterocycles ; Diaziridines ; Diazirines ; Oxaziranes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Since their discovery five years ago, the diaziridines have become an extensive and easily accessible class of compounds. Hydrolysis of these compounds effects a simple synthesis of hydrazine, alkylhydrazines, and N,N′-dialkylhydrazines. They are also powerful oxidizing agents. The rigidity of the three-membered ring gives rise to a few stereoelectronic peculiarities. Investigations on the mechanism of formation of the three-membered rings led to a new synthesis of oxaziranes and to discovery of the isomeric oximes with a three-membered ring structure. The latter decompose readily to form diimide. Diazirines are cyclic isomers of the aliphatic diazo compounds and are surprisingly easy to obtain by dehydrogenation of suitable diaziridines; they are chemically much more stable than the linear isomers. Grignard reagents add onto the N=N double bond without destruction of the three-membered ring. Thermal decomposition yields carbenes.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 460-470 
    ISSN: 0570-0833
    Keywords: Heat resistance ; Fibers ; Polymers ; Materials science ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This survey is principally concerned with papers published since 1959 on hydrocarbon polymers, aliphatic poly(terephthalamide) fibers, poly(hydroxybenzoic acid) films, poly(oxadiazole) fibers, poly(benzimidazole) films, poly(phenyltriazole) films, poly(pyromellitimide) films, and fibers from cyclized poly(acrylonitrile). All these materials have extremely high melting points and satisfactory in-use characteristics at high temperatures.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 0570-0833
    Keywords: Kinetics ; Dipolar cycloaddition ; Cycloaddition ; Heterocycles ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Criteria for the mechanism of 1,3-dipolar cycloadditions which lead to 5-membered rings are provided by the stereoselectivity observed with cis-trans isomeric dipolarophiles, by the effect of solvent and substituents on the rate constants, by the activation parameters, and by orientation phenomena. A concerted addition, which can also be described in terms of molecular orbitals and in which the two new σ-bonds are formed simultaneously, although not necessarily at equal rates, offers the best explanation of the experimental facts.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 459-476 
    ISSN: 0570-0833
    Keywords: Aminoguanidine ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Due to its unique structure, aminoguanidine is capable of reacting as a derivative of hydrazine, guanidine or formamidine. Addition and condensation reactions yield products which can be cyclized to heterocyclic compounds. Frequently, heterocyclics are directly accessible from aminoguanidine in one stage.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 565-598 
    ISSN: 0570-0833
    Keywords: Dipolar cycloaddition ; Cycloaddition ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In contrast to the very large number of special methods applicable to syntheses in the heterocyclic series, relatively few general methods are available. The 1,3-dipolar addition offers a remarkably wide range of utility in the synthesis of five-membered heterocycles. Here the “1,3-dipole”, which can only be represented by zwitterionic octet resonance structures, combines in a cycloaddition with a multiple bond system - the “dipolarophile” - to form an uncharged five-membered ring. Although numerous individual examples of this reaction were known, some even back in the nineteenth century, fruitful development of this synthetic principle has been achieved only in recent years.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 410-420 
    ISSN: 0570-0833
    Keywords: Oligomers ; Pleionomers ; Polymers ; Fibers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The term “oligomer” is defined, and a survey of methods for the isolation and synthesis of cyclic and linear oligoesters, oligourethanes, oligo(acrylonitriles), and oligoamides is presented. The oligomers serve a valuable function as model substances for the investigation of many properties of the corresponding high polymers. This is shown using several examples (infrared spectroscopy, X-ray spectroscopy, viscosity).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 14
    ISSN: 0570-0833
    Keywords: Pyrrolidone ; Polyamides ; Fibers ; Lactams ; Polymerization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The industrial production of capryllactam (1-azacyclononan-2-one) and of laurolactam (1-azacyclotridecan-2-one) starts with cyclization of acetylene or butadeine to give cyclooctatetraene or cyclooctadiene, or cyclization of butadiene to give cyclododecatriene. Further steps are: oxidation of the cyclic hydrocarbon to the ketone, formation of the oxime, and rearrangement of the latter with sulfuric acid. Pyrrolidone can be prepared from acetylene and formaldehyde by way of butyrolactone. The behavior of the lactams during polycondensation is described and the properties of the resulting fibers are compared with those of the known polyamide fibers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 15
    ISSN: 0570-0833
    Keywords: Lactams ; Polymerization ; Fibers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: β-Lactams can be prepared by cyclization of β-aimno acid esters. Recently they have become available also from olefins by addition of N-carbonysulfamyl chloride (isocyanatosulfonyl chloride) and from aldehydes by reaction with N-carbonylsulfamyl chloride and ketene. Condensative or anionic polymerization results in polyamides the chains of which contain many more amide groups than the chains of polyamides of the nylon-6 type. Hence the new polymers resemble silk moreclosely. Fibers and films can be prepared from solution.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 1 (1962), S. 532-537 
    ISSN: 0570-0833
    Keywords: Polyacrylonitrile ; Fibers ; Azatrimethinecyanines ; Dyes/Pigments ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Like all basic dyes, azatrimethinecyanines possess a good dyeing affinity for acrylic fibers. Compounds with isolated nitrogen atoms in the trimethine chain show insufficient light fastness, whereas good to excellent fastness to light is displayed by compounds having neighboring nitrogen atoms in the chain. Thus, a working hypothesis stating that the light fastness of trimethinecyanines on acrylic fibers is improved by progressive replacement of methine groups by nitrogen atoms has been partially confirmed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 17
    ISSN: 0570-0833
    Keywords: Elastomers ; Fibers ; Polyurethanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highly elastic polyurethanes suitable for fiber production can be obtained by various synthetic routes based on diisocyanate polyaddition processes. Macrodiisocyanates obtained from long chain diols and diisocyanates are allowed to react with polyamines during fiber formation (chemical spinning process) or the macrodiisocyanates are treated in solvents (e.g. dimethylformamide) with polyamines to give highly viscous, spinnable solutions of polymer. Both methods yield highly elastic polymers with wide-mesh network structures. The production of polyurethane fibers and their structures and physical properties are described.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 18
    ISSN: 0570-0833
    Keywords: Copolymers ; Fibers ; Vinylidenedicarbonitrile ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinyldendicarbonitrile (Vinylidene cyanide) on free redical catalyzed copolymerization shows a much stronger tendency to form 1:1 alternating copolymers than acrylonitrile. While bulk poly(vinylidene cyanide) fails to crystallize, despite its molecular symmetry, several alternating copolymers are readily crystallizable, notably those containing butadiene, isoprene, isobutylene, or vinylidene chloride. Fibers have been prepared from a number of the higher melting copolymers and examined for physical properties. Fibers from the vinyl acetate and vinyl chloride copolymers show expectional elastic behavior both when dry and wet. The fiber from the vinylidene cyanide |vinyl acetate alternating copolymer (Darvan® nytril fiber) is only moderately oriented and is characterized by exceptional softness and excellent elastic recovery and resilience, both when dry and wet.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 19
    ISSN: 0570-0833
    Keywords: Long periods ; Polyethylene ; Fibers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Meridional reflections appearing in small-angle X-ray diffraction diagrams of drawn polyethylene are caused by a nearly periodic arrangement of crystalline and disordered regions. The long period, which is determined by the average distance between two consecutive crystallites, depends on the method of preparing the sample. The time and temperature dependences of the positions of the small-angle reflections have been investigated. The growth of the long period of unoriented bulk polyethlene and polyethylene single crystal follows the same time dependence as that of stretched films. However, characteristic differences were obseved in the relationship between density and long period; they are attributed to the fact that in single crystals and in material crystallized from the melt, the chains are folded at the boundaries of the crystallites, whereas this in not the case in stretched polyethylene.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...