Behavior of ellagitannins, gallic acid, and ellagic acid under alkaline conditions

Abstract

Examination of the rates of hydrolysis of different ellagitannins under conditions comparable with cold soda and alkaline-groundwood pulping processes showed that some ellagitannins are notably resistant to hydrolysis. The rate of hydrolysis was dependent upon the pH and tempemture of the solution and particularly upon the structure of the compound. Decarboxylation of gallic and ellagic acids was a major reaction under conditions comparable with kraft and soda pulping processes. Gallic acid was much more stable than ellagic acid. There was little decarboxylation of gallic acid in NSSC pulping liquors. Ellagic acid was decarboxylated to high yields of 2,2',3,3',4,4' hexahydroxydiphenyl under kraft and soda pulping conditions. There was less extensive but significant decarboxylation of ellagic acid under NSSC pulping conditions.

Keywords

Eucalyptus, groundwood pulping, neutral sulfite pulping, soda pulping, sulfate pulping, reactions (chemical), hydrolosis, decarboxylation, pH, temperature, carboxylic acids, organic acids, phenols, tannins, ellagic acid, ellagitannins, gallic acid

Citation

Hemingway, Richard W.; Hillis, W.E. 1971. Behavior of ellagitannins, gallic acid, and ellagic acid under alkaline conditions. TAPPI 54(6):933-936