GB513708A - Improvements in the manufacture of hydroxy-aldehydes and hydroxy-ketones - Google Patents

Abstract

513,708. Hydroxy carbonyl compounds. TAYLOR, A. W. C., WOOLCOCK, J. W., TYRER, D., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. April 14, 1938, Nos. 11593, 11594 and 11595. [Class 2 (iii)] A mixture of hydroxy-aldehydes and -ketones containing a large proportion of hydroxyaldehydes and -ketones having 2, 3 or 4 carbon atoms in the molecule, is obtained by the condensation of formaldehyde, at an initial concentration of at least 20 per cent., in aqueous solution or in aqueous alcoholic solution containing not more than 50 per cent. of alcohols, in the presence of an oxide or hydroxide of tin, magnesium, calcium, strontium, barium or preferably lead, in an amount such that the initial pH of the solution does not exceed 8.0, while maintaining the pH of the solution within the limits 4 to 8 throughout the reaction by the addition, continuously or in batches, of one or more basic oxides or hydroxides or organic bases reasonably soluble under the conditions of condensation. Caustic soda -or hydrated lime is preferred as the basic compound, the addition of which may be controlled automatically, and the preferred pH of reaction is between 6.0 and 6.5. It is advantageous to allow the condensation to proceed only to 80-90 per cent. conversion, and also to have present at the start of the condensation a small proportion, e.g., 2¢-5 per cent., of the product of condensation, i.e. by recycling or adding a little of a previous batch. In examples, (1) 0.2 parts of PbO and 5 parts of recycled product are added to a solution of 20 parts formaldehyde in 32 parts methyl alcohol and 48 parts of water and the whole is refluxed for 6-7 hours while maintaining the pH of the solution at 7.0-7.5 by the controlled addition of 0.04 parts of calcium hydroxide in glycol, (2) 37 per cent. formalin together with PbO and recycled product are boiled for 1¢ hours at a pH maintained at 6.0-6.5 by the addition of sodium hydroxide, to give a 50 per cent. yield of hydroxy-aldehydes and -ketones containing 2, 3 or 4 carbon atoms per molecule as determined by the cold reduction of Fehling's solution, (3) reaction was carried out as in Ex. (2) for 38 minutes at a pH of 7.0-7.5 to give a 41 per cent. yield of the lower hydroxyaldehydes and ketones.