Some Factors Affecting the Selective Formation of 2, 4-Bis(hydroxymethyl)-3-pentulose

Abstract

The formose reaction, which was found to give 2, 4-bis(hydroxymethyl)-3-pentulose (2, 4BH-3-P) with high selectivity, was carried out in methanol and/or water in the presence of various alkaline earth salts and potaslium hydroxide at 60°C, monitoring the reaction wi th continuous measurements of redox potential and pH of the reaction mixture.
The effects of these factors on the formose reaction and the com ponent of products were discussed in detail. No influence of anions of barium salts on the product's distribution was observed, but the concentration of the dissolved barium was strongly affected by the kind of anion and the formose reaction rate increased with an increase in its concentration. In the. formose reaction, catalyzed with BaBr2-KOH, below 15 vol% of the amount of water, the formose reaction was not influenced by the amount of water and the main product was 2, 4 (cez.4 5 g lc%), and above 25 v ol% the reaction rate decreased with an increase in th Be H-3-P amount of water and the yield of 2-(hydroxymethyl)glycerol, 3- (hydroxymethyl)pentitol, and 2, 4-bis(hydroityinethy1)pentitol increased up to 54 glc%.
The maintenance of pH of the reaction mixture to a constant value during the reaction or the ratio of [Catalyzer]/[HCHO] is an important factor for the formose reaction to procee d smoothly in water with the alkaline earth salts-KOH catalyst. In methanol, strontium salt was found to give 3-(hydroxymethyl)pentofuranose and 2, 4-BH-3-P with high selectivity. Formdse Reactions. XVII.