SEPARATION OF 2,4-TOLYLENE DIISOCYANATE FROM MIXTURES OF 2,4- AND 2,6-TOLYLENE DIISOCYANATE

摘要

Separation of 2,4-tolylene diisocyanate from a mixture of 2,4- and 2,6-tolylene diisocyanate by cooling the mixture of isocyanate by passage through a heat exchanger to crystallize a portion of 2,4-tolylene diisocyanate to form a slurry containing no more than about 25% by weight 2,4-tolylene diisocyanate crystals suspended in mother liquor, maintaining the resulting slurry for a nominal residence time of at least about 2 hours at about a constant temperature and centrifuging the slurry to separate 2,4-tolylene diisocyanate crystals from the mother liquor.