Replacement of halogen by carboxyl-oxygen

The halogen of trihalides may be replaced analogously to that of mono- and gew-di-halides, no new considerations being involved. The usual reagents are slaked lime at 50°, alcoholic alkali hydroxides, acids, or iron(m) chloride in aqueous solution. Some trichloromethyl compounds are converted into carboxylic acids in excellent yield by heating them in chloroform in the presence of anhydrous iron(m) chloride whilst the appropriate amount of water is dropped in.549 

Such processes have, however, little preparative importance since the starting materials are mostly difficult of access. In a few cases (chloral, 1,1,1-trihalo-acetone) fission of a C-C bond occurs alongside the hydrolysis. Weizmann et al.550 report an interesting synthesis of 2-alkoxy-2-methylpropionic acids they obtained these acids by treating acetone with chloroform and hydrolysing the condensation product with alkali in the presence of an alcohol the hydrolysis presumably proceeds by way of an epoxide  

Interaction T)f 1,1,1 -trichloro-2,2-bis-(p-chlorophenyl)ethane (DDT) and alkali gives, according to the conditions, either bis-(p-chlorophenyl)acetic acid or 2,2-dichloro-1,1 -bis-(/ -chlorophenyl)ethylene.551 

Benzotrifluoride is hydrolysed in 94% yield to benzoic acid when heated in 100% sulfuric acid until the benzotrifluoride layer disappears.552 

Carboxylic acids are rarely prepared in practice from carbonyl chlorides. This hydrolysis occurs when the acid halide is dropped with vigorous stirring into ice-cold water or ice-cold sodium carbonate solution alcoholic potassium hydroxide is required only in exceptional cases. Aromatic acid halides are more stable than their aliphatic counterparts. 

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