142 II. CHEMISTRY OF FATTY ACIDS AND GLYCEROL, 



sanonitrile, 53.5-54.5; pentacosanonitrile, 58-59; and hexacosanonitrile, 

 61-62. 



The aliphatic saturated nitriles are relatively thermostable, and can be 

 distilled without decomposition under reduced pressures. The nitriles be- 

 low the Ci2 member can be distilled at ordinary pressure without destruc- 

 tion, but lauronitrile and the higher homologs are partially decomposed. 

 Ralston and co-workers^'-^ have recently determined the boiling points of 

 the Ce to Ci8 saturated nitriles at \ arious reduced pressures. The densities 

 are much lower than those of the fatty acids, varying at 30 °C. from 

 0.7906 for valeronitrile to 0.8207 for myristonitrile.s27.528 



The refractive indices are likewise lower than for the corresponding 

 acids. They decrease as the temperature is increased, and an abrupt change 

 in slope occurs at 40^5 °C. which is also the case with the acids. The re- 

 fractive indices vary at 50 °C. from 1.3706 for butyronitrile to 1.4370 for 

 stearonitrile ; at 75 °C., these values are 1.3590 and 1.4276, respectively. ^^^ 



Hoerr et aZ.^^" have recently carried out an exhaustive study on solubili- 

 ties of the nitriles. The solubilities in general decrease with an increasing 

 polarity of the solvents. They also follow the general rule of being less 

 soluble with increasing molecular size. 



Nitriles are readily hydrolyzed via the amides to the corresponding car- 

 boxylic acid. The lower members of the series can readily be hydrolyzed 

 to the fatty acids by alkalies on refluxing their aqueous or alcoholic solu- 

 tions. ^^^'^^^ For splitting the higher nitriles, it may be necessary to carry 

 out the hydrolysis under pressure, to accelerate the reaction. The break- 

 down may likewise be accomplished in the vapor state, with steam at 

 420 °C., using thorium oxide or aluminum oxide as the catalyst. ^^-^ 



c'. Reactions of Nitriles: The hydrolysis of the nitriles can be ef- 

 fected by means of concentrated acids. There are two equilibria involved, 

 i.e., nitrile -^ amide and amide — » acid, which respond differently to the 

 concentration of the acid. Since the rate of the reaction will be governed 

 by the slower of the two hydrolysis constants, the maximum conversion of 

 the nitrile to the acid may not necessarily entail the optimum rate for both 

 reactions. At lower acid concentrations the rate of hydrolysis of the several 

 mineral acids is similar. At higher concentrations, hydrochloric acid has 



"6 A. \V. Ralston, W. M. Selby, and W. O. Pool, Ind. Eng. Chem., 33, 682-683 (1941). 

 62' R. Merckx, J. Verhulst, and P. Bruylants, Bull. soc. chim. Belg., 42, 177-198 (1933). 

 "8 B. Daragan, Bull. soc. chim. Belg., 44, 597-624 (1935). 

 *29 A. Dorinson and A. W. Ralston, /. Am. Chem. Soc, 66, 361-362 (1944). 

 "0 C. W. Hoerr, E. F. Binkerd, W. O. Pool, and A. W. Ralston, J. Org. Chem., 9 

 68-80 (1944). 



"1 E. Frankland and H. Kolbe, Ann., 65, 288-304 (1848). 



"2 R. Adams and C. S. Marvel, J. Am. Chem. Soc, 42, 310-320 (1920). 



"3 A. Mailhe, ComfL rend., Ill, 245-247 (1920). 



