Relationship between stereostructure of poly(vinyl alcohol) and its acetalization reaction

Abstract

Abstract By measurement of peak areas in the dioxymethylene region of high‐resolution NMR spectra of partly formalized poly(vinyl alcohol), PVA, the relationship between tacticity of PVA, rate of formalization reaction, and stereochemical configuration of poly(vinyl formal) was studied. Formation of cis ‐formal at an isotactic part of a PVA chain is faster than that of trans ‐formal at a syndiotactic part. When the reaction is allowed to continue for a long period, the migration of formal rings from syndiotactic to isotactic portions is observed. Partition of formal rings in partly formalized PVA into cis and trans types is discussed in connection with the tacticity of original PVA and degree of formalization. The rate‐determining step of acetalization reaction is also discussed.