METHOD OF PRODUCING 4,4-DIMETHYL-1,3-DIOXANE Russian patent published in 2012 - IPC C07D319/06 

FIELD: chemistry.

SUBSTANCE: invention relates to petrochemical industry and more precisely to production of monomers for synthesis of polymers. More specifically, the invention relates to methods of producing 4,4-dimethyl-1,3-dioxane (DMD) which is used as an intermediate product in production of isoprene and polyisoprene rubber. The method is realised via condensation of isobutylene, taken in form of an isobutylene-containing fraction, with formaldehyde in form of an aqueous solution in the presence of an acid catalyst at temperature 75-105°C, pressure 1.5-2.5 MPa in a column reactor, while feeding reactant streams through direct flow from bottom-up into the reactor, separating the reaction mass into water and oil layers, evaporating the water layer, adding the starting aqueous formaldehyde solution to the residue after evaporation and recirculation of the obtained mixture into the condensation zone, with separation of the end product and high-boiling by-products from the oil layer via fractionation. Condensation is carried out in a reactor consisting of separate, series-connected 2-6 sections lying one on top of the other, with successive combined feeding of reactant streams down each section through a nozzle of a distribution device, outlet of the reaction mass from the top of each section, cooling in an external heat exchanger and feeding down the next section.

EFFECT: method reduces the amount of by-products to 190-200 kg per 1 ton of DMD, increases DMD output by 2,5-4% from the same amount of reactants and reduces the amount of metal used to make the reactor by about three-fold.