4-Chlorophthalic acid → 4-Chlorophthalic anhydride

Reaction equation

ClC1C=C(C(Cl)=O)C(=CC=1)C(Cl)=O.ClC1C=C(C#N)C(=CC=1)C#N.[Cl:25][C:26]1[CH:27]=[C:28]([C:35]([OH:37])=[O:36])[C:29](=[CH:33][CH:34]=1)[C:30]([OH:32])=O>>[Cl:25][C:26]1[CH:27]=[C:28]2[C:35](=[O:36])[O:37][C:30](=[O:32])[C:29]2=[CH:33][CH:34]=1

Participants

Reactant 3

HCID 69644-Chlorophthalic acid

HCID 872134-Chloro-1,2-dicyanobenzene

HCID 150445624-Chlorobenzene-1,2-dicarbonyl dichloride

Product 1

HCID 670444-Chlorophthalic anhydride

Procedure

In a conventional acidic hydrolysis, the 4-chlorophthaloyl chloride or 4-chlorophthalonitrile of Examples 7 or 8 is hydrolyzed to 4-chlorophthalic acid which, upon dehydration at over 180°-200° C., will afford a high yield of 4-chlorophthalic anhydride.