Synthesis of isoprene from 1,3-dioxolane and isobutylene

SUBSTANCE: invention relates to a method of extracting organic compounds (DMD, TMK, unsaturated alcohols, methylal) from an aqueous layer during synthesis of dimethyl dioxane in production of isoprene from isobutylene and formaldehyde via partial extraction of said compounds from the end of the column for stripping the aqueous layer of the isobutane-isobutylene fraction, coming in for synthesis of dimethyl dioxane in weight ratio 1:0.8 - 1.0, followed by fortification and removal of methanol from formaldehyde, characterised by that the raffinate from partial extraction of organic compounds is subjected to additional extraction of isobutane-isobutylene fraction in ratio of 1:0.5 - 0.8 and the obtained raffinate is mixed with formaldehyde water obtained from decomposition of DMD, and also with the distillate of the formalin fortification column and taken for fortification and removal of methanol from formaldehyde, followed by feeding the distillate from the column for removing methanol from formaldehyde for extraction of organic compounds concentrated therein through the return isobutane fraction, extracted after synthesis of dimethyl dioxane in ratio 1:1.0 - 1.2, followed by feeding the extraction for extraction of the return isobutane fraction once more.

Synthesis of isoprene from 1,3-dioxolane and isobutylene", ..

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.


Synthesis of Arborescent Isoprene Homopolymers

Method of preparing 4,4-dimethyldioxane-1,3 - …

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.