122 



II. CHEMISTRY OF FATTY ACIDS AND GLYCEROL 



with the higher fatty acids. These esters readily form films which find 

 application in the waterproofing of paper^^^ or as a protective coating for 

 metals. ^'^ Mixed esters of cellulose have been prepared in which several 

 different fatty acids make up the acid components. ''^^ The monoesters of 

 cellulose are insoluble in organic solvents ; as the number of fatty acid resi- 

 dues is increased, they become increasingly soluble in organic solvents and 



Table 44 



Melting Points (°C.) of Palmitate Esters of Various Polyhydric Alcohols and 



Carbohydrates" 



" Most of the data are adapted from K. S. Marklcy, Falty Acids, Interscience, New- 

 York, 1947, p. 290. 



" H. Gault and P. Ehrmann, Caoutchouc & Guttapercha, U, 13532-13533, 13603- 

 13605 (1927); Chem. AbsL, 21, 1350, 2794 (1927). Cited by A. W. Ralston, Falty Acids 

 and Their Derivatives, Wiley, New York, 1948, p. 569. 



their properties become more similar to those of the fats. Most of the 

 polyesters decompose before melting. On hydrolysis of the esters, cellu- 

 lose and the fatty acids can be regenerated, indicating that esterification 

 proceeds without injury to the cellulose molecule. The melting points of 

 the cellulose esters are lowered as an increasing number of fatty acids are 

 combined with them. 



The amylose component of starch is believed to retain fatty acids by a 



*»» J. A. Mitchell, U. S. Patent No. 2,193,831 (Mar. 19, 1940). 



*•" C. R. Fordyce and G. D. Iliatt, U. S. Patent No. 2,170,016 (Aug. 22, 1939), 



