CHEMICAL PROPERTIES OF FATTY ACIDS AND RELATED COMPOUNDS 12.') 



ical amount of lauryl aldehyde has been reported to be produced by this 

 method/^' Other catalysts which have been used include copper, zinc, or 

 aluminum mixed with chromium. 



Another important method for the synthesis of aldehydes is by heating 

 the calcium or barium soaps with a large excess of calcium or barium 

 formate. The following reaction results: 



RC\ /0-CH ^0 



,0-Ca+CaC *2RC-H + 2CaC05 



Calcium Calcium Alfleh>(Ie 



soap formate 



Dodecanal, tetradecanal, hexadecanal, and octadecanal have been satis- 

 factorily prepared by the calcium salt-calcium foimate method. ■'^^ Cal- 

 cium carbonate is frequently mixed with tlie reactants to slow down the re- 

 action and prevent excessive sintering. An excess of calcium formate 

 tends to minimize ketone formation. This method is more satisfactory for 

 the lower members of the series than for the higher aldehydes. Somewhat 

 better yields have been claimed when the reaction is carried out in an auto- 

 clave in the presence of an inert solvent. '*^^ 



A closely allied method involves the preparation of the aldehydes by 

 heating the free fatty acids and formic acid with a decarboxylating cat- 

 alyst. "^^^ This method has been successfully applied to the synthesis of 

 dodecanal, "^^^ nonanal,^^^ decanal,^" and even of the unsaturated com- 

 pound, oleic aldehyde,'**^ from the corresponding acids. Soaps at high 

 temperatures likewise react with formaldehyde to yield aldehydes. ^^^ 



Another important synthesis of the aldehydes is by decomposition of the 

 ozonides of the unsaturated acids, either by direct heating in a strongly 

 alkaline medium^'"' or by catalytic hydrogenation under pressure. It is 

 also possible to obtain aldehydes having one less carbon than the original 



"1 A. Halasz, Compt. rend., 209, 1000-1003 (1939). 



"2 F. Krafft, Ber., IS, 1413-1418 (1880). 



^•^ H. T. Bohme, A.-G., Brit. Patent No. 382,929 (Mar. 17, 1932). 



«^ I. G. Farbenind., A.-G., Brit. Patent No. 414,148 (Feb. 6, 1933). 



''^ S. S. Nametkin and O. M. Khol'mer, Sintezy Dushistykh Veshchestr, Sbornik Statei, 

 55-57 (1939); Chern. Abst., 36, 3629 (1942). 



*'^ S. S. Nametkin and R. Y. Shagalova, Sintezy Dushistykh Veshchestv, Sbornik Statei, 

 274-281 (1939); Chem. Abst., 36, 3781 (1942). 



*" O. Osipova, Masloboino Zhinovoe Delo, 11, 378-379 (1935); Chem. Abst., SO, 1025- 

 1026 (1936). 



"38 1. G. Farbenind., A.-G., French Patent No. 750,467 (1937); cited by A. W. Ralston, 

 Fatty Acids and Their Derivatives, Wiley, New York, 19^8, p. 815; German Patent No. 

 660,735 (Dec. 5, 1938). 



"9 A. W. Ralston and R. J. Vander Wal, Brit. Patent No. 509,203 (Julv 12, 1939); 

 U. S. Patent No. 2,145,801 (Jan. 31, 1939). 



"■'» S. Isikawa and A. Mivata, Science Repts. Tokyo Bunrika Daigaku, A3, 257-263, 

 (1939); Chem. Abst., 34, 98i (1940). 



