Benzoic anhydride, />,//-dichloro

Hydrolysis of Benzoyl Chloride. Early experiments demonstrated that 3b, 3c, 4, and 5 are effective catalysts for the conversion of benzoyl chloride to benzoic anhydride in well-stirred suspensions of dichloro-methane-0.5 M aqueous sodium bicarbonate (equation 8) (2, 3). The results... 

Benzoic anhydride treated with a little ZnGl2 then dropwise with 0.625 mole a,a-dichloro-dimethyl ether, and heated 2 hrs. at 70-100° benzoyl chloride. Y 98%.—Similarly from p-toluenesulfonic acid monohydrate with 2.5 moles a,a-dichlorodimethyl ether p-toluene-sulfonyl chloride. Y 92,5%. F. e., also from carboxylic acids and alkali carboxylates, s. A. Rieche and H. Gross, B. 92, 83 (1959). 

Preparation by hydrogenolysis of 6-(benzyloxy)-3,3 -dichloro-2,4,4, 6 -tetramethoxy-2 -methyl-benzo-phenone (SM) under hydrogen in the presence of 10% Pd/C at 25°. SM was obtained by condensation of 3-chloro-4,6-dimethoxy-2-methyl-benzoic acid with 4-chloro-3, 5-dimethoxyphenol benzyl ether in the presence of trifluo-roacetic anhydride in methylene under nitrogen for 80 min (50%) [1179]. m.p. 196-197° [1179] H NMR [1179], IR [1179], MS [1179]. 

Preparation by hydrogenolysis of 2,2, 4-tris-(benzyloxy)-3,5,5 -trichloro-4 -methoxy-6,6 -di-methylbenzo-phenone (SM) in the presence of 10% Pd/C in ethyl acetate containing concentrated hydrochloric acid (5 drops) (>90%) [1339], SM was obtained by Friedel-Crafts acylation of 5-(benzyloxy)-2-chloro-3-methoxytoluene with 2,4-bis-(benzyloxy)-3,5-dichloro-6-methyl-benzoic acid in the presence of trifluoroacetic anhydride in refluxing ethylene dichloride for 5 h (42%). 

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