PROCESS FOR SEPARATING TECHNICALLY PURE 2,4- DIISOCYANATOTOLUENE OR ISOMER MIXTURES HAVING AN INCREASED CONTENT OF 2,4-DIISOCYANATOTOLUENE FROM ISOMER MIXTURES OF 2,4-AND 2,6 DIISOCYANATOTOLUENE

A PROCESS FOR SEPARATING TECHNICALLY PURE 2, 4-DIISOCYANATOTOLUENE OR ISOMER MIXTURES HAYING AN INCREASED CONTENT OF 2,4-DIISO- CYANATOTOLUENE FROM ISOMER MIXTURES OF 2,4- AND 2,6-DIISOCYANATOTOLUENE Technically pure 2, 4-diisocyanatotoluene or an isomer mixture having an increased 2, 4-diisocyanato-toluene content is obtained from an isomer mixture of 2,4- and 2,6-diisocyanatotoluene. The 2,4- and 2,6diisocyanatotoluene mixture is first cooled to a temperature of from 4 to 9.degree.C and further cooled to between -2 to -6.degree.C at a rate of 0.5 to 3.degree.C per hour. The temperature of the mixture is maintained at that temperature for at least 30 minutes. Any liquid present is removed and the solid remaining is then melted. Melting is preferably carried out by heating the solid at a rate of 0.5 to 3.degree.C per hour until the remaining solid has a 2,4-diisocyanato-toluene content of at least 98%. The liquid melt is removed and the solid having the desired 2,4-diisocyanato-toluene content is then melted.