The addition of the elements of methoxymercuric acetate to 2-methyl-1-phenylpropene-1 occurs to give 2-methyl-2-methoxy-1-phenylpropylmercuric acetate. This structure could not be demonstrated by replacement of chloromercuri by halogeno because 2-methyl-1,2-dimethoxy-1-phenylpropane and 2-methyl-2-phenylpropanal or 3-phenylbutanone-2 were obtained instead of the expected halides. Indeed the 2-methyl-2-methoxy-1-phenylpropyl iodide which Tiffeneau, Orekhoff, and Lévy reported as the reaction product of 2-methyl-1-phenylpropene-1, mercuric acetate, and iodine in methanol is yet unknown, since their product actually comprised the di-ether and aldehyde described above. The structure proof of 2-methyl-2-methoxy-1-phenylpropylmercuric chloride has been accomplished by treatment with hydrazine hydrate. The isolation of 2-methoxy-2-methyl-1-phenylpropane and the two diastereomeric 2,5-dimethyl-2,5-dimethoxy-3,4-diphenylhexanes shows that this reaction has proceeded through intermediate formation of the 2-methoxy-2-methyl-1-phenylpropyl radical.