4,5-Dichlorophthalic acid → 4,5-Dichlorophthalic anhydride

Participants

Reaction Steps

A suspension of 4,5-dichlorophthalic acid [(XVII), X=4--Cl, Y=5--Cl, 50.0 g, 0.213 mol] and acetic anhydride (70 mL) was heated to reflux until dissolution occurred. A distilling head was then attached and 30 mL of distillate was removed. The solution was cooled to room temperature whereupon a precipitate appeared. This solid was filtered, washed with anhydrous ether and dried in vacuo to provide the product (40.4 g, 87%) as a tan solid, m.p. 189°-192° C.

Provenance & Evidence