Willgerodt reaction side reactions

It has been tentatively suggested that one mechanism underlies the Willgerodt reaction and the Kindler modification of it. A labile intermediate is first formed which has a carbon—carbon bond in the side chain. The scheme is indicated below it postulates a series of steps involving the addition of ammonia or amine (R = H or alkyl), elimination of water, re addition and eUmination of ammonia or amine until the unsaturation appears at the end of the chain then an irreversible oxidation between sulphur and the nitrogen compound may occur to produce a thioamide. 

It should be kept in mind that reactive functions such as amino, nitro, and formyl groups may undergo oxidation, reduction, or condensation imder conditions of the Willgerodt reaction, hence their presence as substituents on the starting compounds may lead to various side reactions. Alkyl groups, alkoxyls, hflogens (if inert) and similar unreactive groups appear to have no effect on the course of the reaction. 

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