CHEMISTKY OF GLYCEROL 161 



versed.^'™"'"'-' The solvent may })e a deciding factor as regards the posi- 

 tion which the halogen occupies/"^ 



Hypochlorous acid, HOCl, as well as the bromine and iodine counter- 

 parts, combine with the unsaturated linkage to give the lialohj'drins; 

 in the presence of aqueous or alcoholic alkalies, the halohydrins are con- 

 verted to the epoxide which, on hydrolysis, yields the dihydroxy-acidJ"'*"™^ 

 The reaction between oleic and hypochlorous acid is pictured below: 



CH3(CH2)7CH:CH(CH2)7C00H i^^:^— *CH3(CH2)7CH-GH(CH2)7COOH 



OH CI 

 Oleic acid Oleic acid halohydrin 



^^^►CH3(CHe)7CH-CH(CH2)7C00H— ^^5^CH3(CH2)7CH-CH(CHe)7COOH 



OH OH 



Oleic acid 9,10-Dihydroxy- 



epoxide stearic acid 



Many other reactions are possible with saturated and unsaturated fatty 

 acids which are of more interest to the general organic chemist than to the 

 fat chemist. These reactions include substitution of the halides in the 

 aliphatic chain, dehalogenation, and dehydrohalogenation, the reaction 

 with sulfuric acid to form sulfonic acids, and many others. For a dis- 

 cussion of the reactions of greatest interest, the reader is referred to ]\Iark- 

 ley* and to Ralston.* 



5. Chemistry of Glycerol 



Approximately 10% of the fat molecule consists of glycerol, which occurs 

 in combination with the fatty acids. Glycerol (or glycerine in the earlier 

 literature) is a trihydric alcohol having the formula CHoOH-CHOH-- 

 CH2OH. In contradistinction to the fats and to the higher fatt}^ acids, 

 glycerol is largely insoluble in most of the fat solvents such as chloro- 

 form, benzene, petroleum ether, or anhydrous diethyl ether; on the other 

 hand, it is readily soluble in water, and is miscible with it in all proportions. 

 The same is true for ethyl alcohol. In some cases, glycerol also acts more 

 satisfactorily as a solvent for a number of salts than does alcohol or water. 



™ E. Erlenmeyer, Ber., 13, 305-310 (1880). 



™' R. Fittig, Ber., 13, 955-956 (1880); Ann., 200, 21-96 (1880); 208, 111-121 (1881); 

 255, 1-144 (1889): 283, 47-148, 269-341 (1894). 



'«2 F. Fichter aiui W. Langguth, Ann., 313, 371-381 (1900). 



™' J. AValker and J. S. Lumsden, J. Chem. Soc, 79, 1191-1197 (1901). 



"«' A. Albitskii, ./. Rus.s. Phys. Chem. Soc, 31, 76-100 (1899); cited by K. S. Markley, 

 P\itt!/ Acid.'i, Interscipnce, New York, 1947, pp. 343-344. 



™= A. Albitzky, ./. prakt. Chem. [2], 61, 65-94 (1900). 



™6 B. H. Nicolet and T. C. Poulter, /. Am. Chem. Soc, 52, 1186-1191 (1930). 



