2,6-Di-tert-butyl-p-cresol precursors recovery - from mother liquors obtd by crystallising reaction prods of isobutylene and paracresol

摘要

Process for recovering precursors of 2,6-di-tert, butyl-p-cresol in a mother liquor obtd. by crystallising 2,6-di-tert.butyl-p-cresol (I) made by alkylating p-cresol with isobutylene, the mother liquor being comprised of diisobutylene and low and high polymers of cresol which inhibit the crystallisation of the (I), consists of (a) thermally cracking the mother liquor at 200-250 degrees C in the presence of an acid catalyst to crack the low- and high cresol polymers; (b) steam distilling the cracked mixt. to eliminate diisobutylene; (c) realkylating the steam distilled reaction mixt. by addn. of isobutylene; and (d) crystallising the additional (I) formed.