Homogeneous Reaction of Formose Formation Catalyzed by Complexes of Calcium Hydroxide

Abstract

Rates of formose formation and Cannizzaro reaction taking place simultaneously in homogeneous alkaline solution of formaldehyde have been measured at 40 to 60°C with Ca(OH)2 catalyst which is dissolved as soluble complexes: Cl Ca(OH), -carbphydrate or C2Cj Ca(OH)2formaldehyde.When the reaction solution contains no carbohydrate but the complex C2C, the Cannizzaro reaction prevails over the formose formation for a long induction period. As the latter rate increase autocatalitically after the period, the former rate is suppressed to minor order. On the other hand, when the reaction solution contains complex C/D composed of glucose or xylose, the formose formation reaction is initiated without any induction period, suppressing the Cannizzaro reaction rate from start. Both reaction rates are independent of the concentration of HCHO but proportional to the concentration of the respective complex, i. e. the formose reaction to Cl and the Cannizzaro reaction to C2C. These experimental results can be interpreted by the mechanism where the formose reaction proceeds through a reaction intermediate involving the complex catalyst Cl and Cannizzaro reaction through the complex C2C.It is also examined that the catalytic activity of the complex of this type Cl depends remarkably upon the kind of alkaline earth metal or of carbohydrate which is the component of complex.