Process for the separation of ortho-, meta- and para-tolunitrile from ternary mixtures of isomers

摘要

Process for the separation of ortho-, meta- and para-tolunitrile from ternary isomer mixtures by distilling the ortho-tolunitrile from these mixtures at pressures of 10 2 to 10 5 Pa and a reflux ratio of 1: 1 to 200: 1 and the remaining binary mixture of meta- and para-tolunitrile is concentrated by distillation to over 75 mol% para-tolunitrile and the para-tolunitrile freezes out at temperatures below 26 ° C., and a process for the preparation of suitable ternary isomer mixtures by isomerization of pure ortho- , meta- or para-tolunitrile or their mixtures at 380 to 580 ° C on zeolite catalysts.