Benzaldoximes Beckmann rearrangement

Acidic zeolites, K-10 clay and silica are highly active and selective catalysts for the dehydration/Beckmann rearrangement reactions of aldoxhnes (benzaldoxime and 4-methoxybenzaldoxime) for the synthesis of nitriles and amides . 

The fact that under the same conditions acetophenone oxime does not form amides, but remains intact, also provides evidence against the classical Beckmann rearrangement. The conditions found can be employed for preparing amides from nitriles and aldoximes, especially when the latter contain fragments unstable to acids. In the absence of DMSO, benzaldoxime is dehydrated with alkali only at the boiling point (200°C). 

InCls can be used as an efficient reagent for the conversion of aldoximes to nitriles and ketoximes to amides. Benzaldoxime gives benzonitrile, and benzophenone oxime is converted to the Beckmann rearrangement product, benzanilide, in 95% yield (Scheme 8.135) [179]. Sonication of a mixture of a carbonyl compound, an amine, and diethyl phosphite in fhe presence of a catalytic amount of InCls produces a-aminophosphonate (Scheme 8.136) [180]. 

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