13C-NMR STUDY ON RELATIONSHIP BETWEEN STEREOSTR- UCTURE OF POLY (VINYL ALCOHOL) AND ITS KETALIZATION REACTION
13C-NMR研究聚乙烯醇微观立构规整性与丙酮缩酮化反应的关系

Through reaction between the hydroxy groups of poly(vinyl alcohol) (PVA) and acetone, various polyvinyl ketal copolymers (PVKT) containing <70% ketal ring-units in the products were obtained. The relationship between tacticity of PVA, rate of ketalization reaction and structural characterization were carried on PVKT by13C-NMR spectroscopy at 22.5 MHz. Ketal rings in partly ketaled PVA were assigned into MM-cis, MR-cis and RR-trans types, and corresponding equilibrium constants Kmm, Kmr, Krr, and rate of ketalization reaction were discussed.