METHOD OF SYNTHESIS OF β- OR C-C-KETOACETALS Russian patent published in 1997 - IPC

FIELD: chemical technology, organic chemistry. SUBSTANCE: C₁₄- and C₁₉-ketoacetals were synthesized by condensation of the corresponding ketone of β-ionone or C₁₈-ketone with alkylformate in medium of an anhydrous organic solvent, for example, hexane in the presence of alkaline catalyst sodium methylate or ethylate followed by acetylation with low-molecular alcohol in the presence of sulfuric acid as an acid catalyst. Low-molecular alcohol is loaded at 30-45-fold mole excess with respect to the parent ketone and fed it by two stages. At the first stage alcohol is fed after ketone addition at amount 25-75 weight % of the parent ketone weight followed by exposition at stirring up to preparing the homogeneous mobile mass; at the second stage alcohol is added at acetylation directly after it preliminary mixing with sulfuric acid and cooling to (-5)-(-20) C. Methanol is used preferably as low-molecular alcohol and methylformate - as alkylformate. Synthesized β-ketoacetals were used in vitamin A production. EFFECT: improved method of synthesis, increased yield of products. 2 cl, 1 tbl