ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
(1) Polymerization of 2-vinylpyridine in p-chlorotoluene solution produced a polymer which, when oxidized with potassium permanganate in dilute sulfuric acid, gave no chlorophthalic acid, but a 35.7% yield of p-chlorobenzoic acid (based upon the halogen content of the polymer). Therefore, incorporation of the aromatic groups in the polymer, probably in the step of chain transfer, occurred by reaction with the side chain and not the nucleus of the p-chlorotoluene. The absence of chlorophthalic acid was significant, for a similar oxidation of α-(p-methylbenzyl)pyridine gave a 3% yield of terephthalic acid as well as a 23% yield of 2-(4-carboxybenzoyl)pyridine. (2) Permanganate oxidation of this same polymer in 25% sulfuric acid gave a 27% yield of p-chlorobenzoic acid. This represents the maximum yield of halobenzoic acid to be expected from a polyvinylpyridine containing trace quantities of halophenyl and pyridine nuclei separated by a chain of two or more carbon atoms. In contrast, similar oxidations in 25% sulfuric acid of α-(p-bromobenzyl)- and α-(p-chlorobenzyl)pyridine gave much smaller yields (16 and 14%, respectively) of the corresponding halobenzoic acids. In concentrated acid, the heterocyclic rings form stable salts and oxidation of the benzylpyridine type structure leads to preferential cleavage of the benzene nucleus. (3) Initiation of the polymerization of 2-vinylpyridine with N-nitroso-p-bromoacetanilide formed a polymer which, upon oxidation with potassium permanganate in 25% sulfuric acid, gave a 31% (average) yield of p-bromobenzoic acid. Since this yield is that expected from a polymer in which pyridine and bromobenzene rings are separated by a chain of two or more carbon atoms, beta carbon atoms addition in chain initiation by a bromophenyl radical is substantiated. (4) Polymerization of 2-vinylpyridine in bromobenzene solution provided a polymer which, upon oxidation with permanaganate in 25% sulfuric acid, gave only a 6% yield of bromobenzoic acid, corresponding to a bromobenzylpyridine structure in the polymer. Reasons are given why this data supports but does not prove the hypothesis that chain transfer consists of substitution in the bromobenzene nucleus by a polymer radical possessing a 2-pyridylmethyl structure.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1956.120199205
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