3,5-Dichlorobenzene-1,2-dicarboxylic acid → 3,5-Dichlorophthalic anhydride

Participants

Reaction Steps

3,5-Dichlorophthalic acid (3.36 g, preparation given in Example 1 of U.S. Pat. No. 5,086,188) was refluxed with 10 mL of xylenes while the water generated from the cyclization was collected in a Barrett trap. After refluxing for 5 hours the reaction was cooled, and the xylenes were removed under vacuum. The resultant solids were dried overnight in a vacuum desiccator to give 2.32 g of 3,5-dichlorophthalic anhydride, mp 90° to 94° C.

Provenance & Evidence