OXIDATION OF ALKENES BY MERCURIC SALTS

Abstract

The α-oxymercurials of cyclohexene, 2-methyl-1-phenylpropene-1, and the geoisomers of stilbene have been shown to be the intermediates in the oxidation of these alkenes by mercuric nitrate and other salts, usually in methanol. These intermediates are stable in the oxidation environment and their alkoxy groups appear intact in the oxidation product; indeed organomercurials without vicinal alkoxy groups are likewise oxidized. The reaction products from alkenes in methanol are 1,2-dimethoxyethanes, 1,1-dimethoxyethanes, and (with mercuric nitrate) 1-methoxy-2-nitroxyethanes, formation of the latter being most rapid. The oxidation is stereospecific, each geoisomer yielding its characteristic dia-stereomeric products. It is catalyzed by acids such as nitric acid but not by nitrate ion, though neither affect the ratio of products. This over-all second-order reaction, first-order in organomercurial and first-order in mercuric salt, becomes over-all first-order with mercuric acetate when it is catalyzed by boron fluoride. Combination of the catalyst with the organomercurial must be rate-controlling. The similarity of the oxidation and the acid decomposition reactions of organomercurials is discussed.