Bromination of 4-tert. butyl toluene - giving mainly corresp. benzal bromide deriv., useful for making 4-tert. butyl benzaldehyde

摘要

Method comprises reacting 4-tert:butyltoluene (I) with 1.2-3.2 moles bromine at opt. in presence of an inert organic solvent or diluent. Partic. reaction is with 2-2.1; 2.2-3.2 or 1.2-1.9 moles bromine per mole (I). Also new are mixts. contg. (wt.%) (a) 90-93% 4-tert. butylbenzal bromide (II); 3-4% 4-tert.butylbenzyl bromide (III) and 4-6% 4-tert.butylbenzotribromide (N); (b) 15-95% (IV) and 5-85% (II), or(c)40-85% (II) plus 15-60% (III). The reaction mixts. can be hydrolysed to prod. 4- tert.butylbenzaldehyde (a starting material for perfumes) and 4-tert.butylbenzoic acid (a component of alkyd resins and starting material for varnishes). The proportions of (II), (III) and (IV) in the mixt. can be varied by controlling the amt. of bromine used; any (III) formed can be sepd. and recycled for further bromination. This gives an overall (II) yield of 95-100%. The method does not require any free radical catalysts or irradiation, and relatively crude (I) can be used.