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  • 1
    Electronic Resource
    Electronic Resource
    Beurteilung der Fähigkeit sensorischer Gutachter bei der sensorischen Prüfung von Fruchtsäften und -nektaren (1992)
    Springer
    European food research and technology 195 (1992), S. 429-433 
    Details
    ISSN: 1438-2385
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Zusammenfassung Für die Beurteilung der Fähigkeit von sensorischen Gutachtern können die Urteilstreue (Wiederholfähigkeit), der Bewertungsmaßstab und die Bewertungsschwankung als geeignete Maßzahlen betrachtet werden. Aus den Punktzahlen für 26 Fruchtsaftproben wurden die 3 Fähigkeitsfaktoren je Gutachter berechnet. Die Zahlenwerte haben gezeigt, daß die überprüften sensorischen Gutachter über einen entsprechenden Bewertungsmaßstab verfügen und ihre auch die richtige Anwendung der Punktzahlen zum Ausdruck bringende Bewertungsschwankung, abgesehen von einem „vorsichtigen“ Gutachter, normal ist. Die insgesamt nur „befriedigende“ Urteilstreue könnte dagegen durch entsprechende Übung weiter verbessert werden.
    Notes: Summary The earlier elaborated and accepted sensory ability testing was proved to be useful for controlling and qualifying the assessing activity of panellists. The repeating ability expresses the agreement of scores within a short time interval. For its determination a certain number of samples are evaluated twice (or more) within one sample series. The repeating ability was calculated as the average difference of repeated scores. The evaluation accuracy of an assessor compares his decisions to the average of the whole panel. It is calculated as an average difference between his scores and the mean scores of the whole panel. Scoring deviation expresses how inclined an assessor is to give a higher score for samples of better quality or a lower score for those of lesser quality, in other words, whether his scores vary in a narrow, “medium” or a broader score range. The reference base is the deviation of the score given by the panel. Scoring deviation is the ratio of standard deviation of individual assessors and the square root of the average variance of panel members. These indices worked out and adapted to experimental data are discussed, of which especially the repeating ability and scoring deviation is interrelated. The application and calculation of such ability indices are necessary to follow with attention the activity of assessors, to consider them for the selection of panel members and in the development of their sensory memories. Unacceptable repeating ability, biassed evaluation accuracy (too rigorous or too mild) or high and low scoring deviation can lead to disqualification. The regular (possibly computer-aided) ability testing may give direct information to panel members to judge, correct and develop their own sensory abilities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01191711
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  • 2
    Electronic Resource
    Electronic Resource
    Versuche zur Synthese des Polystachins (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1068-1077 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: An Attempted Synthesis of Polystachin[1′RS(3RS)]-1-(2,3-Dihydro-4-hydroxy-6-methoxy-1-benzofuran-3-yl)-2-methyl-1,2-propandiol (21), a partial structure of the title substance 1 was synthetized in 11 steps from phloroglucinol. The key steps were the oxidative rearrangement of the benzylidenacetone derivative 5 by Tl(NO3)3 in methanol to yield the 2-aryl-1,1-dimethoxythane 8 followed by ring closure involving the hydroxy group of 9 liberated by debenzylation. Conversion of 21 into compounds of structure 1 was just as unsuccessful as the synthesis of rac-polystachin (rac-1) from tachrosin (23 via the flavone derivative 29.
    Notes: [1′RS(3RS)]-1-(2,3-Dihydro-4-hydroxy-6-methoxy-1-benzofuran-3-yl)-2-methyl-1,2-propandiol (21), eine Teilstruktur der Titelsubstanz 1, wurde aus Phloroglucin in 11 Schritten synthetisiert. Als Schlüsselreaktion diente die oxidative Umlagerung des Benzalacetonderivates 5 mit Tl(NO3)3 in Methanol zu dem 2-Aryl-1,1-dimethoxyethan 8 gefolgt vom Ringschluß an der durch Entbenzylierung freigesetzten Hydroxygruppe von 9. Die Überführung von 21 in Verbindungen der Struktur 1 blieb ebenso erfolglos wie die Synthese von rac-Polystachin (rac-1) aus Tachrosin (23) über das Flavonderivat 29.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840603
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  • 3
    Electronic Resource
    Electronic Resource
    Oxidative Umlagerung von α-Benzylidenketonen mit Thallium(III)-nitrat in Methanol (1980)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 1283-1295 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Oxidative Rearrangement of α-Benzylideneketones with Thallium(III) Nitrate in MethanolSterically unhindered arylidene- and diarylideneacetones 1 or 2 having electron releasing aryl groups yielded with thallium(III) nitrate in methanol β-ketoacetals 3, 4 and 5, respectively. Electronegatively substituted 1f and sterically hindered 1g and 1h gave the 4-arylcrotonic esters 7 and by-products, while 1,3-dibenzylidenacetone (2a) yielded besides the expected products also the branched acetal esters 13a and 13b. Formation of the anomalous products 7 and 13 can be rationalized assuming a common cyclopropanone type intermediate.
    Notes: Sterisch unbehinderte Aryliden- und Diarylidenacetone 1 bzw. 2 mit elektronenspendenden Aryl-gruppen liefern mit Thallium(III)-nitrat in Methanol die β-Ketoacetale 3, 4 bzw. 5. Das elektronegativ substituierte 1f sowie die sterisch gehinderten Acetonderivate 1g und 1h ergeben die 4-Arylcrotonsäureester 7 und Nebenprodukte, während aus 1,3-Dibenzylidenaceton (2a) neben den erwarteten Produkten auch die verzweigten Acetalester 13a und 13b entstehen. Für die Bildung der anomalen Produkte 7 und 13 wird als gemeinsames Zwischenprodukt ein Cyclopropanonderivat vorgeschlagen.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198019800812
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  • 4
    Electronic Resource
    Electronic Resource
    Oxidation von 1,3-Diphenyl-1,3-propandionen mit Thallium-(III)-nitrat in Methanol (1980)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 1271-1282 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Oxidation of 1,3-Diphenyl-1,3-propanediones with Thallium(III) Nitrate in MethanolOn oxidation with thallium(III) nitrate in methanol, 1,3-diphenyl-1,3-propanediones 1 rearrange to give 3-oxo-2,3-diphenylpropanoic esters 2 and products derived therefrom. However, 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanediones 1h-k undergo oxidative cyclization to 2-aroyl-3(2H)-benzofuranones 5. The alkali and acid catalysed cleavage of 5 is discussed.
    Notes: Bei der Oxidation mit Thallium(III)-nitrat in Methanol werden die 1,3-Diphenyl-1,3-propandione 1 zu den 3-Oxo-2,3-diphenylpropansäureestern 2 und deren Folgeprodukte umgelagert. Die 1-(2-Hydroxyphenyl)-3-phenyl-1,3-propandione 1h-k werden dagegen oxidativ zu den 2-Aroyl-3(2H)-benzofuranonen 5 cyclisiert.  -  Der durch Alkalilauge und Säure katalysierte Abbau von 5 wird diskutiert.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198019800811
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  • 5
    Electronic Resource
    Electronic Resource
    Alkalilabilität von in 2-Stellung anionisch aktivierten Acetalen (1978)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1978 (1978), S. 107-117 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Acetals with Anionic Activation in Position 2: Sensitivity towards AlkaliAcetals 1-5 with a hydrogen atom in position 2, activated by a neighbouring carbonyl or cyano group, two ester groups, or one phenyl and one ester group, undergo alkali-catalysed alkoxy exchange and/or alcohol elimination (to vinyl ethers 6). In the presence of water they undergo hydrolysis.
    Notes: Die Acetale 1-5, die in 2-Stellung ein durch eine benachbarte Carbonyl- oder Nitrilgruppe, zwei Estergruppen oder eine Phenyl- und eine Estergruppe aktiviertes Wasserstoffatom enthalten, neigen zum alkalikatalysierten Alkoxyaustausch und/oder zur Alkoholabspaltung (zu den Vinylethern 6) sowie in Anwesenheit von Wasser zur Hydrolyse.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197819780113
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  • 6
    Electronic Resource
    Electronic Resource
    Versuche zur Synthese des Multijuginols (1985)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 995-1003 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: An Attempted Synthesis of Multijuginol(3RS,3aSR,8aSR)-2,3,3a,8a-Tetrahydro-3-hydroxy-4,6-dimethoxy-4,6-dimethoxy-2,2-dimethylfuro[2,3-b]benzofuran (29), a partial structure of the title substance 2, was synthesized in 11 steps from phloroglucinol, but could not be transformed into rac-2. Some partly unexpected reactions of the intermediates, e.g. a pyridine-catalyzed transannular hydrogen migration (22 → 23), are described.
    Notes: (3RS, 3aSR,8aSR)-2,3,3a,8a-Tetrahydro-3-hydroxy-4,6-dimethoxy-2,2-dimethylfuro[2,3-b]benzofuran (29), eine Teilstruktur der Titelsubstanz 2, wurde aus Phloroglucin in 11 Schritten synthetisiert, konnte jedoch nicht in rac-2 übergeführt werden. Einige z. T. Unerwartete Reaktionen der Zwischenprodukte, u.a. eine durch Pyridin katalysierte transannulare Wasserstoffverschiebung (22 → 23), werden beschrieben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198519850513
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