OBTAINING TOLUENE 2,6-DIISOCYANATE FROM A MIXTURE CONTAINING TOLUENE 2,6-DIISOCYANATE AND TOLUENE 2,4-DIISOCYANATE

摘要

A method for obtaining substantially pure toluene 2,6-diisocyanate from a mixture of the 2,4 and 2,6 isomers of toluene diisocyanate, wherein at least one crystallising-melting cycle is performed on the mixture of said isomers to separate out the toluene 2,6-diisocyanate isomer. In an alternative embodiment, the mixture is contacted, prior to the crystallising-melting cycle, with a compound or catalyst capable of converting part of the toluene 2,4-diisocyanate isomer therein, and the reacted 2,4 isomer is separated. Said method is advantageous in that usable by-products are produced.