METHOD FOR PRODUCTION OF 4,4-DIMETHYL-1,3-DIOXANE Russian patent published in 1996 - IPC

FIELD: synthesis of isoprene. SUBSTANCE: desired product is prepared by condensation of isobutylene (as isobutane-isobutylene fraction) with aqueous solution of formaldehyde in the presence of oxalic acid as catalyst. Thus obtained reaction mixture is separated in oil and aqueous layers, aqueous layer being recirculated for synthesis of 4,4-dimethyl-1,3-dioxane. Waste isobutane-isobutylene fraction is affected by secondary rectification, temperature of the vat of the column being 50-65 C. 80-90 % of said fraction are distilled and vat liquid is removed in condensation zone. EFFECT: decreases energy expenses, decreases expense of isobutylene and isobutane.