摘要:

AbstractIm Zusammenhang mit dem Startprozeß der spontanen Polymerisation von Styrol entstehen auch bei tiefen Temperaturen gesättigte cyclische Oligomere, 1‐Phenyl‐tetralin und 1‐Phenyl‐4‐phenyläthyl‐tetralin. Kinetische Untersuchungen zeigen, daß die Geschwindigkeiten dieser Reaktionen wesentlich größer sind als die Geschwindigkeit der konkurrierender Startradikal‐Bildung. Die gaschromatographischen Ergebnisse weisen außerdem daraf hin, daß die Bildung der linearen Oligomeren, 2,4‐Diphenyl‐buten‐(1) und 2,4,6‐Triphenyl‐hexen‐(1) unabhängig vom Startmechanismus de

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650101

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe study of the reaction of some methylenebisphenols with chloranil in ethanol and also of a phenol formaldehyde condensate prepared by acid catalysis, reveals that quinone methide is formed in the self‐cure of quinoid phenol formaldehyde resin. The quinone methide reacts with ethanol to give an adduct. The structure of the alcohol adduct is identified by NMR and IR data and by means of pyrolysi

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650102

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractLes polymères du titre sont préparés par polycondensation en milieu acide (Pa) et en milieu alcalin (Pb) du formaldéhyde avec les monomères phénoliques optiquement actifs N‐benzoylL‐tyrosine (TyB) et N‐(p‐hydroxyphénylsulfonyl)‐L‐phénylalanine (PhHPS). Leurs compositions chimiques sont vérifiées à partir des spectres IR, de la masse (Mr) du motif monomère et de la comparaison avec d'autres polycondensats du même type. PaTyB, PbTyB et PbPhHPS ont la structure chimique attendue, par contre, PaPhHPS fait l'objet d'une réaction secondaire qui est identifiée. Les pouvoirs rotatoires de PaTyB et PbTyB dépendent du milieu de polycondensation. L'ècart varie d'un solvant à l'autre. II ne s'annule que dans la potasse 0,l M en presence de fortes concentrations de sels (KCl, LiBr). L'influence de l'eau dans le dioxanne et des sels dans la potasse 0,l M est étudiée par dispersion rotatoire (DRO). Les contributions de DRO partielles negatives mises en évidence sont attribuées des espèces chimiques labiles entre les groupes amide portés par les motifs monomè

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650103

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractEs wird eine Apparatur beschrieben, die einen Reaktor, kombiniert mit einem Gaschromatographen, umfaßt und die es gestattet, Umsetzungen kurzkettiger Olefine bei der Metathesereaktion schnell und einfach zu erfassen. Die Leistungsfähigkeit der Apparatur wird u. a. am Beispiel der Metathesereaktion von Penten‐2 in Gegenwart des Katalysator‐systems WCl6/C2H5OH/(C2H5)3Al2Cl3demonst

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650104

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractIt has been shown that the reaction of equimolar quantities of butadiene and epoxide with alkali metal in tetrahydrofuran results in the formation of the dimer diol\documentclass{article}\pagestyle{empty}\begin{document}$${\rm RCH}({\rm OH}){\rm CH}_2 ({\rm C}_4 {\rm H}_6 )_2 {\rm CH}_2 {\rm CH}({\rm OH}){\rm R} $$\end{document}on subsequent hydrolysis. Yields up to 70% have been obtained with lithium metal, but with sodium the reaction is less efficient.

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650105

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe mechanism of radiation‐induced polymerizations in the solid state has been a subject mostly open to speculation. As radiation usually generates several kinds of active species (radicals and ions) it is difficult to find out, which of these actually causes polymerization.We have developped a method distinguishing between cationic and anionic active centers. Cationic polymerizations are terminated by addition of a base such as sodium alkoxide in a suitable solvent. The alkoxide is incorporated into the polymer as an endgroup. This endgroup is determined analytically after isolation and purification of the polymer. The incorporation of alkoxy endgroups into the polymer is a proof of the occurrence of polymer chains with cationic chain ends. It was shown by this method that crystalline trioxane, polymerized by γ‐rays at 60°C, contains polyoxymethylene cations. It is assumed that with these cationic active centers propagation is similar to polymerizations initiated by LEWIS acids. Anionic chain ends can be detected by an analogous way. Polymerizations are terminated by addition of excess alkyl iodide which produces alkoxy endgroups from the anionic chain ends. Surprisingly, in the radiation‐induced polymerization of crystalline trioxane some anionic chain ends were also found in the polymer. It is assumed that these anions do not propagate and that they are only counter‐ions of the propagating cationic c

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650106

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe thermal degradation of poly(oxycarbonylethylene) (poly‐β‐propiolactone) has been investigated within a temperature range of 180–220°C and under various pressures. The degradation begins with a considerable decrease in molecular weight, followed by an accelerating formation of acrylic acid. The reaction involves the following steps:1Random chain scission of polymer chains by typical ester pyrolysis with the formation of fragments one of which containing a carboxylic group the other one a CC‐double bond at the chain end (Eq. (1)).2Formation of the volatile acrylic acid by scissions at the chain end, the amount of acrylic acid or the weight‐loss increasing with the number of fragmentations (Eq. (2)).3Autocatalysed acidic cleavage of the polyester fragments into an α,β‐unsaturated ester and an acid as shown with low molecular model compounds (Eq. (8)).Substitution of the labile α‐hydrogen atoms in poly(oxycarbonylethylene) by methyl groups—such as in poly(oxycarbonyl‐1,1‐dimethylethylene)—reduces the rate of degradation drastically. This observation together with the results obtained in the pyrolysis of the low‐molecular model compounds, ethyl β‐acetoxypropionate and β‐acetoxypropionic acid

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650107

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractLa cyclopolymérisation du diméthacrylate de dihydroxy‐2,2′‐diméthyl‐5,5′‐diphénylméthane (II) a été réalisée en milieu benzène à 80° avec l'azobisisobutyronitrile comme amorceur, en milieu toluène à −500°C avec le butyllithium comme amorceur et en tétrahydrofuranne (THF) avec le naphthalène sodium. Les polymères obtenus ont été soumis à l'hydrolyse basique, les polyacides résultants traités par le diazométhane donnent les polyméthacrylates de méthyle correspondants dont la tacticité a été étudiée en NMR (100 MHz). La réduction des polymè;res a été effectuées par LiAlH4en milieu THF. Des alcools polyméthylallyliques ont été isolés. Les résultats semblent montrer l'influence de la matrice II sur

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650108

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe addition chlorination of a series oftransandcispolyalkenamers yields poly(1,2‐dichloroalkamer)s characterized by a certain degree of crystallinity. By X‐ray analysis of the polymers and examination of model compounds, the observed crystallinity has been shown to be due to stereoregularity in sequences of monomeric units.The question whether this stereoregularity has to be attributed to stereospecificity in chlorine addition or to the statistical occurrence of units having the same configuration is examined in view of X‐ray data and of steric induction in model compounds. A hypothesis concerning the mechanism of chlorine addition is pro

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650109

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe influence of different solvents on the copolymerization behaviour ofN‐methyl acrylamide with styrene and methyl methacrylate has been investigated. The calculated relative reactivities ofN‐methyl acrylamide towards both the polystyryl and poly(methyl methacrylyl) radicals (1/r2) are practically unaffected by the reaction medium; on the contrary, the relative reactivities of both styrene and methyl methacrylate monomers towards the poly(N‐methyl acrylamide) radical (1/r1) are remarkably influenced by the reaction solvents. A comparison both with unsubstituted and disubstituted acrylamides polymerized under the same conditions has been

ISSN:0025-116X    

DOI:10.1002/macp.1973.021650110

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY