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 a method of producing 4,4-dimethyl-1,3-dioxane (DMD) - an intermediate product in the production of isoprene and polyisoprene rubber, which are monomers for synthesis of polymers. The method is realised via condensation of formaldehyde in form of an aqueous solution with isobutylene in form of an isobutane-isobutylene fraction in the presence of an acid catalyst at temperature 80-110°C for 1.3-2.5 MPa, followed by separation of the reaction mixture into an oil layer and a water layer, evaporating the water layer, adding to the residue after evaporation of the starting aqueous formaldehyde solution and recirculation of the obtained mixture into the condensation zone, with separation of the end product from the oil layer via fractionation. Condensation is carried out in a reactor consisting of three separately lying one on top of the other and series-connected sections with combined feeding of reactants into the reactor from bottom-up while reducing temperature by 1-10°C in the second and third sections on the path of the reactant stream and pressure by 0.03-0.3 MPa below the pressure of saturated isobutane vapour at temperature in the given points of the reactor.

EFFECT: method reduces the amount of formed high-boiling by-products by 1 ton of the obtained DMD, increases output thereof by 2,5-4%, and also reduces costs of making the reactor due to more efficient use of the reaction volume.

2 cl, 4 ex