| 摘要 |
PCT No. PCT/FR95/00366 Sec. 371 Date Jan. 21, 1997 Sec. 102(e) Date Jan. 21, 1997 PCT Filed Mar. 24, 1995 PCT Pub. No. WO95/26332 PCT Pub. Date Oct. 5, 1995A method for obtaining substantially pure toluylene 2,6-diisocyanate from a mixture of the 2,4 and 2,6 isomers of toluylene diisocyanate, wherein at least one crystallizing-melting cycle is performed on the mixture of said isomers to separate out the toluylene 2,6 diisocyanate isomer. In an alternative embodiment, the mixture is contacted, prior to the crystallizing-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. |
