Acid-Catalyzed Degradation of Poly(2-Butyl-1,3,6-Trioxocane)
MASSACHUSETTS UNIV AMHERST DEPT OF POLYMER SCIENCE AND ENGINEERING
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Polyacetals, owing to the acid sensitivity of the acetal linkage, are attractive candidates for end uses in which acid sensitivity is a desirable property, e.g. photo- or electron-resists. Acid catalyzed degradation of poly 2-butyl-1,3,6-trioxocane 1 has been studied. With ethyl tosylate as the catalyst, the cyclic monomer 2 was the major product. The minor products are cis and trans isomers of C3H7CHCH-OCH2CH2OCH2CH2OH, and three stereoisomers of C3H7CHCH-OCH2CH2OCH2CH2O-CHCH-C3H7 elucidated by 1H and 13C NMR, IR, electron impact and chemical ionization MS, and in the case of 2 also by comparison with an authentic sample. With 98 H2SO4 as the catalyst 2 is only a minor product. The major products are diethylene glycol, valeraldehyde, and 1,4-dioxane with some 2-butyl-1,3-dioxolane. Capillary GCMass spectrometry led to identification of the following less abundant products tri-n-propylbenzene, alpha, beta- unsaturated aldehydes and cyclic dimer. The products of H2SO4-catalyzed decomposition of polymer were also obtained by heating monomer 2 with H2SO4. A detailed mechanism for the formation of the 8-member ring 2 in the decomposition is proposed which involves unzipping proceeds via open carbocation intermediates. According to the principle of microscopic reversibility, the same open carbocation is the propagating species in the polymerization of 2 under similar conditions.
- Polymer Chemistry