METHOD OF PRODUCING ISOPRENE Russian patent published in 2012 - IPC C07C11/18 C07C2/86 C07C1/20 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing isoprene via liquid-phase reaction of isobutylene and formaldehyde or substances which are sources thereof, for example, 4,4-dimethyl-1,3-dioxane and trimethyl carbinol, in the presence of an aqueous solution of an acid catalyst at temperature 140-180°C and pressure 0.8-1.6 MPa in a reaction-separation apparatus, having a heat input zone, a contacting zone, successive separation zones, a reaction mass circulation loop with extraction of reaction products and a balance amount of water from the separation zone in form of a vapour stream with subsequent cooling, condensation and separation, feeding the liquid stream of the aqueous solution of catalyst for extraction and sequent return into a heating zone, wherein pressure in the reaction zone is kept higher than pressure of saturated water vapour corresponding to temperature in the reaction zone, characterised by that pressure in the separation zones is kept higher than pressure of saturated water vapour corresponding to contacting temperature, wherein the reaction stream from the contacting zone is fed into the first separation zone without throttling, from which the vapour stream enters the gaseous part of the second separation zone with drop of pressure by 0.05-0.4 MPa with subsequent output for cooling and condensation, and the liquid stream from the first separation zone is fed into the liquid part of the second separation zone, from which 30-70% of the liquid stream separated from high-boiling organic compounds is returned to the reaction-separation apparatus, and the remaining part of the liquid stream is fed for cooling, extraction and recirculation into the reaction-separation apparatus.

EFFECT: low power consumption.

1 cl, 2 dwg, 6 ex, 1 tbl