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NITRATION AGENTS AND METHODS MORE RARELY USED^113

Moreover, diphenylhydroxylamine derivatives and p- dinitrotoluene may be formed,

e.g. :

It seems to be certain that the oxynitration reaction in the presence of mercury

salts proceeds through the formation of phenylmercuric nitrate. The isolation

of phenylmercuric nitrate from a reaction mixture in dilute nitric acid by several

authors (Carmack and his co-workers [135], Titov and Laptev [71], and also Bro-

ders [124]) favours this view. If an intermediate nitroso compound is formed in the

reaction its formation should be ascribed to the reaction between phenylmercuric

nitrate and nitrous acid. This view, based on earlier experiments of Baeyer [136],

Bamberger [137], Smith and Taylor [137a], has since been confirmed by Westheimer,

Segel and Schramm [138], who considered the nitroso compound formed from

an organo-mercuric compound to be the principal intermediate product in the

Wolffenstein and Böters reaction.

Nitrogen dioxide plays an important role in the reaction. It is this compound

that is responsible for the conversion of mercury aryl nitrates into nitroso deriva-

tives.

Westheimer and his co-workers formulated the reaction mechanism in the

following way :

(55a)

(55b)

The nitrosobenzene formed in the reaction (55b) can then react in either of two

ways :

(1)

(55c)