Bis(dimethoxymethyl) peroxide and bis(1,1-dimethoxyethyl) peroxide

Abstract

The title compounds 1 and 2, the first examples of peroxides polysubstituted at the a and a' positions by alkoxy groups, are formed by benzophenone sensitized photooxygenation of trimethoxymethane and 1 , 1 ,1-trimethoxyethane, respectively. No peroxide was formed from tetramethoxymethane. Allowing 98% hydrogen peroxide and trimethoxymethane to stand results in an 80% yield of 1, so that 1 and 2 are probably formed by such a disproportionation reaction during photooxygenation. Compound 1 is converted quantitatively to methanol, methyl formate, and dimethyl carbonate in pyridine solution at 60°C. In acidic methanol both 1 and 2 undergo solvolysis rapidly with exclusive cleavage of the carbon -peroxy oxygen bond. Signals for the ether and peroxy oxygens of 1 appear at 34 and 263 ppm and those of 2 appear at 40 and 264 ppm in the 170 nuclear magnetic resonance spectrum. Luminescence results when 1 and 2 are heated to 150°C. IntroductionThe present study grew out of a desire to learn about the properties of trimethoxymethyl hydroperoxide and bis(trimethoxymethyl) peroxide in connection with another problem. A possible route to these compounds might be the benzophenone-sensitized photooxygenation of trimethoxymethane. Cyclic acetal derivatives of some aldehydes have been oxidized to hydroperoxides and peroxides with oxygen (1) but trimethoxymethane does not appear to have been converted to such products, although the central C-H bond ought to be relatively reactive with a bond dissociation energy (BDE) of about 89 kcal/mol. This value is estimated as follows. Replacement of an alkyl group by a methoxy group on a hydrocarbon lowers the C-I3 BDE by an amount that decreases with decreasing C-H BDE of the corresponding hydrocarbon (2). The BDE of the central C-H bond in isobutane is 93.3 kcal/mol (3) and substitution of a methyl group by a methoxy group should lower the BDE by about 3 kcal/mol (2). Replacement of the two remaining methyl groups by methoxy groups would lower the BDE more, but by decreasing amounts estimated to be 1 and 0.5 kcal/mol. Although attack on the central C-H hydrogen should be relatively easy, none of the desired peroxide or hydroperoxide was formed in the reaction.