Other Esters of Carboxylic Acids

The sugars and their derivatives have been esterified with many other organic acids. Among these are the fatty acids and cinnamic acid 107). Most of the products have been made by the action of acyl halides and pyridine on sugars. The fatty acid esters are similar in properties to the natural fats, the glycerol esters. 

Considerable interest has been shown in the partially esterified esters of the sugar alcohols and their anhydrides because of their surface-active properties. For this reason, the methods of preparation have received much study (see p. 397) (108). 

The monopalmitate of ascorbic acid (109) has been prepared by a method (110) that has been applied only to a few other carbohydrates. The method consists of reacting ascorbic acid and fatty acid in 95% sulfuric acid at room temperature. Since the esterification is reported to take place for primary alcohol groups, the method may have value in the preparation of other pure monoesters. The monoesters of ascorbic acid offer promise as antioxidants for edible fats and oils (111). 

Polymerizable esters of sugars are made by treatment of sugars with methacrylic anhydride and pyridine (112). 

Solutions of glucose pentamethacrylate gel in the presence of cobalt naph-thenate or of benzoyl peroxide. 

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