GB404975A - Improvements relating to the production of penta-erythrite - Google Patents

Abstract

In the preparation of penta-erythrite by the alkaline condensation of formaldehyde with acetaldehyde, the reaction is interrupted just before the point at which there is a minimum of reducing substances present, thereby securing the maximum yield. Test samples are taken at intervals and the amount of reducing substances present, viz. unreacted aldehydes and intermediate or bye-products of reducing character, is estimated by titration with Fehling's solution or silver hydroxide solution or electrometrically. When the minimum is approached, the condensation, which has been proceeding at a temperature below 60 DEG C., is interrupted by lowering the temperature to below 20 DEG C. and by removing or neutralising the alkaline condensing agent. If desired, the condensation may first be slowed down by lowering the temperature and then interrupted by elimination of the alkaline agent. In a modification of the process, smaller amounts of the alkaline agents are employed than the equivalent quantity, e.g. 85--90 per cent of the calculated amount. The process may be operated continuously or discontinuously, and an apparatus is described for the continuous operation. Examples are given, in which caustic soda and lime are employed as the alkaline agent and yields of nearly 80 per cent of the theoretical are obtained.