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-dimethoxypr opane with 1,2-propylene glycol at 25 degreesC in neutral solutions were st udied by C-13 NMR spectroscopy. Under these conditions, 1,1-dimethoxymethan e does not react with the glycol. Only the primary OH group of tile glycol participates in the acetal interchange. The reactions of 1,1-dimethoxyethan e 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 m olar ratio 1,1-dialkoxyalkane : glycol. In the system 1,1-dimethoxypropane- 1,2-prolylene glycol, the equilibrium concentration of the cyclic acetal sl ightly increases with temperature in the range 25-80 degreesC.