METHOD FOR PREPARING 4,4-DIMETHYL-1,3-DIOXANE Russian patent published in 2005 - IPC

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for preparing 4,4-dimethyl-1,3-dioxane that represents an intermediate product in manufacturing isoprene. Method involves condensation isobutylene as isobutylene-containing fraction with formaldehyde an aqueous solution in the presence of acid catalyst at 80-100°C, under pressure 1.6-2.0 MPa with recirculation of evaporated an aqueous layer. 4,4-Dimethyl-1,2-dioxane and mixture of high- boiling by-side products are isolated from oily layer of the reaction mass. Mixture of high-boiling by-side products is distilled off in vacuum fractionating column and prepared distillate in the amount 10-20 wt.-% of feeding the column is recovered to the condensation zone. Invention provides reducing waste in process, enhanced output of 4,4-dimethyl-1,3-dioxane being without increasing in consumption of the parent raw. Method provides reducing amount of high-boiling products and the yield of 4,4-dimethyl-1,3-dioxane by 2-4 wt.-%.

EFFECT: improved method for preparing.

3 cl, 1 tbl, 4 ex