Process for the preparation of p-bromotoluene

摘要

A crude bromotoluene mixture comprising at least 70 wt % of a mixture of p-bromotoluene and o-bromotoluene, and wherein the weight ratio of p-bromotoluene:o-bromotoluene is in the range of 50:50 to 99:1 is cooled to a temperature at which crystals of product enriched in p-bromotoluene are formed in a first residual mother liquor. After removing the residual mother liquor from the crystals of product enriched in p-bromotoluene, the crystals are partially melted to form a mixture of residual higher purity p-bromotoluene in the form of crystals, and a second mother liquor having a higher content of o-bromotoluene than said first residual mother liquor. This higher purity p-bromotoluene and the second mother liquor are separated from each other. The entire procedure starting with the above cooling step can be repeated as a second stage and again as a third stage each time using as the initial feed the residual higher purity p-bromotoluene that is separated from the second mother liquor of the preceding stage. Product of 99.5 wt % purity can be formed in this manner.