Acetic Anhydride → ethyl 2-acetyl-3-methylbut-2-enoate

Participants

Reaction Steps

To a solution of ethyl diacetyl-acetate maintained at 5°-10° [which can be prepared according to the method described in Helv. Chim. Acta, 35, 2280 (1952)] in 400 ml of anhydrous ether there were added 110 ml (0.33 mole) of a solution of 3 M methyl-magnesium bromide in ether. The reaction mixture was stirred for 24 hours at room temperature. After cooling, 50 ml of acetic acid anhydride were added and the whole was allowed to stand for 2 hours at room temperature, whereupon it was poured into ice-water. After separation, the organic phase was washed with a 5 % aqueous solution of NaOH, then with water, whereupon it was dried (Na2SO4) and concentrated. The subsequent distillation of the residue yielded 16.1 g (63 %) of ethyl α-isopropylidene-acetoacetate, b.p. 94°-98° /8 Torr. A pure sample was obtained by purification of the said product by chromatography on a colum (silica gel and benzene) followed by vapour phase chromatography.

Provenance & Evidence