METHOD FOR PREPARING 2-ETHYLHEXANOL Russian patent published in 2007 - IPC C07C31/125 C07C29/14 

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of 2-ethylhexanol that is used in manufacturing plasticizing agents of high quality, solvents and lubricating materials. Method involves the hydrogenation reaction of 2-ethylhexenal at increased temperature and pressure in regiment of incomplete conversion of 2-ethylhexenal and recycle of nonconverted 2-ethylhexenal to the hydrogenation step and isolation of the end 2-ethylhexanol by rectification and hydropurification on nickel-containing catalyst at increased temperature and pressure. Concentrate of 2-ethylhexenal is used a raw for hydrogenation prepared by condensation of n-butyric aldehyde, and the hydrogenation process is carried out in liquid phase under pressure 200-300 atm, temperature 100-220⁰C and using nickel-containing catalyst. Isolation of crude 2-ethylhexanol from hydrogenizate containing, except for 2-ethylhexanol, also C₈-aldehydes, C₈-unsaturated alcohols, C₁₂-acetals, C₁₂-ethers and esters and other oxygen-containing impurities with boiling point near that of 2-ethylhexanol is carried out by rectification under vacuum in four columns: in the first column light impurities are isolated, in the second column unreacted C₈-aldehydes are isolated, in the third column crude 2-ethylhexanol is isolated, and in the fourth column 2-ethylhexanol is extracted additionally from the third column vat residue. As a recycle to the hydrogenation mixture of fraction of unreacted C₈-aldehydes from upper part of column and 2-ethylhexanol taken in the mass ratio of sum of C₈-aldehydes to 2-ethylhexanol in the range = (0.03-0.5):1, and in the mass ratio fresh raw : recycle = (0.3-3):1 is fed to the hydrogenation step. Isolation of recycle fraction of C₈-aldehydes in the second column is carried out at the pressure value on upper part of column 50-200 mm of mercury column, temperature difference between 12-th theoretic plate from upper and upper part of column 15-35⁰C with consumption wherein potential removal of 2-ethylhexanol in column distillate is 1-5 wt.-%. Method provides synthesis of 2-ethylhexanol of high quality and high yield and to prolong working life of the hydrogenation catalyst.

EFFECT: improved method of synthesis.

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