A New Synthesis of Dialkoxymethane. The Magnetic Nonequivalence of Methylene Protons in Certain Dialkoxymethane

Dimethyl sulfoxide (DMSO), under acidic conditions, is known to yield formaldehyde as one of its decomposition products. A new method of synthesizing dialkoxymethanes, which consists of the treatment of alcohols with a DMSO-PPA (polyphosphoric acid) mixture, has been shown to be convenient and also generally applicable. Under mild conditions, five primary alcohols and four secondary alcohols are converted to the corresponding formals in 50—80 and 30—40% yields respectively. Dimethyl disulfide, bis(methylthio) methane and methylthiomethyl ether and an oxidation product of the alcohol have been shown to be the main by-products in this reaction. The examination of the NMR spectra has revealed that the acetal methylene protons of dialkoxymethanes made from (±)-secondary alcohols are observed as an AB quartet and as a singlet, each arising from meso and racemic compounds, respectively.