ANOMALOUS MELT CONDENSATION BEHAVIOR OF PURE ISOMERS OF PROTOCATECHUIC ACID-DERIVATIVES

Separation of a mixture of regio isomers of 6- and 7-carboxy-2-hydroxy methyl-1,4-benzodiosane (1) was successfully carried out by the fracti onal crystallization of their acetyl derivatives. Pure 1a (or 1b) gave an infusible product upon heating at 280 degrees C for 90 (or 30) min under reduced pressure, while a mixture of the regio isomers 1a and 1 b polymerized to yield a high-molecular weight spinnable polyester und er the same conditions.