METHOD OF OBTAINING ISOPRENE Russian patent published in 2008 - IPC C07C11/18 C07C1/20 C07C2/86 

FIELD: chemistry.

SUBSTANCE: invention relates to the method of obtaining isoprene by liquid-phase interaction of formaldehyde and isobutylene or the substances, which are their sources, for example 4, 4-dimethyl-1, 3-dioxane and trimethyl-carbinol, in the presence of the aqueous solution of an acidic catalyst, achieved at elevated temperatures and pressure with the obtaining of the products of the reaction and the remaining quantity of water in the form of steam flow, with subsequent cooling, by condensation and by separation into an aqueous and an organic layer, with the processing of the organic layer, which includes the isolation of hot isobutylene, isoprene, hot trimethyl-carbinol and antecedents of isoprene, including the isolation of hot isobutylene, isoprene, hot methyl-hydropropane, fractions of the hydrocarbons C₈-C₁₀ and carbonyl connections C₅H₁₀O and the high temperature boiling remainder, with the processed aqueous layer, with the discharge of organic products, and with the withdrawal of the liquid flow of the aqueous solution of the catalyst for extraction, with the subsequent return into the zone of synthesis, in this case the removal of trimethyl-carbinol, methyl-dihydropropane and the antecedents of isoprene, fractions of hydrocarbons C₈-C₁₀ and carbonyl connections C₅H₁₀O are accomplished by azeotropic rectification with the addition of water in the necessary quantity for the forming of the azeotrope with the distilled products in the column.

EFFECT: it makes it possible to carry out a continuous process with the recycling of the antecedents of isoprene isolated from the products of the synthesis, to avoid the worsening of the indices of the synthesis, exclude the losses of trimethyl-carbinol and the antecedents of isoprene, to improve the indices of expenditure of raw materials and power consumption.

6 cl, 6 ex, 1 dwg