METHOD OF PRODUCING ISOPRENE FROM ISOBUTYLENE AND FORMALDEHYDE WITHOUT ISOLATING INTERMEDIATE PRODUCTS Russian patent published in 2024 - IPC C07C11/18 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing isoprene from isobutylene and formaldehyde without isolating intermediate products in the presence of water-soluble acids, for example orthophosphoric acids, with traditionally used schemes of separation of end products of synthesis: isobutylene, isoprene, pyrans and resins. Method is characterized by that mixing a solution of formaldehyde in water, containing 20–30 wt.% formaldehyde, up to 3 wt.% orthophosphoric acid, with isobutylene with a concentration of not less than 99.5 wt.%, fed in ratio of 1.3–1.7 mol per 1 mol of formaldehyde; obtained mixture is fed into reactors, three of which are tubular with intense heat removal and three or more are devices with a mixer and a cooling jacket for deep depletion of formaldehyde to 0.7–0.5 wt.%, in which the reaction of isobutylene and formaldehyde takes place in the liquid phase at temperature of 95–98 °C and an excess pressure of 20–22 kg/cm²; spraying all reaction products after liquid-phase synthesis in reactors together with unreacted components through nozzles with pressure drop of 1 kg/cm² into vertical reactor tubes, upper and lower covers of which are connected to each other by a circulation pipe, which provides for the return of the hot acidic solution to the reaction zone located in the plane of the spraying nozzles, wherein the process of formation of reaction products takes place at pressure of 25–35 kg/cm² and temperature of 190–200 °C; cooling to 40 °C an aqueous phase containing an acid and resinous products, together with condensed organic products (isobutylene, isoprene, pyrans and light resins), in a refrigerator, then the mixture is subjected to stratification in a settling tank, and water purified from resins is passed through a layer of sulphocationite in a vertical apparatus—ion exchanger for precipitation of corrosion products.

EFFECT: multiple reduction of steam consumption, reduced production of by-products and reduced consumption of isobutylene and formaldehyde during isoprene production.

1 cl, 1 dwg