Features of Acetal Interchange of 1,1-Dialkoxyalkanes with 1,2-Propylene Glycol in Neutral Solutions

Reactions fo 1,1-dimethoxymethane, 1,1-dimethoxyethane, and 1,1-dimethoxypropane with 1,2-propylene glycol at 25°C in neutral solutions were studied by 13C NMR spectroscopy. Under these conditions, 1,1-dimethoxymethane does not react with the glycol. Only the primary OH group of the glycol participates in the acetal interchange. The reactions of 1,1-dimethoxyethane and 1,1-dimethoxypropane with the glycol, along with the linear acetals, yielded 2-alkyl-4-methyl-1,3-dioxolanes. The product ratio depends on the molar ratio 1,1-dialkoxyalkane : glycol. In the system 1,1-dimethoxypropane-1,2-propylene glycol, the equilibrium concentration of the cyclic acetal slightly increases with temperature in the range 25-80°C.