306 IV. WAXES, HIGHER ALCOHOLS, ETC. 



with waxes. Thus, the waxes of apple and pear cuticles apparently play a 

 protective role in the case of these fruits. 



On the other hand, lanolin, which consists partly of a mixture of esters of 

 cholesterol with palmitic, stearic, and oleic acids, acts in much the same 

 way as do the cuticle waxes, and provides a resistant coating for wool fibers 

 and for the skin, not only of sheep but of practically all fur-bearing animals. 

 In the case of beeswax, this substance acts as a structural element. Fin- 

 ally, in some cases, wax may supplant the triglyceride in the plant. Mc- 

 Kinney and Jamieson^ have called attention to the absence of glycerides in 

 the ether-soluble portion of the seed of the Simmondsia chinensis (califor- 

 nica) (goat-nut, jojoba); 48.3% of the lipid consists of the alcohols doco- 

 senol and eicosenol, which alcohols are combined chiefly with docosenoic 

 and eicosenoic acids. This is a typical wax, and its presence in such a large 

 amount represents a unique situation in the plant. The subject of waxes is 

 treated comprehensively from both the chemical and the technological 

 standpoint in the recent monograph of Warth. ^ 



(1) Composition of True Waxes 



Much information about the composition of waxes can be gleaned from 

 an inspection of the hydrolysis products. The alcohols so liberated can 

 readily be separated from the soaps, since they continue to be insoluble in 

 water after saponification, while the soaps can be washed out in water. 

 However, because the rupture of the ester linkage takes place with so much 

 difficulty in the case of the waxes, the saponification is necessarily pro- 

 longed and difficult. If it is not complete, not only will the ether-soluble 

 residue contain the alcohols but it will be contaminated with the remaining 

 unhydrolyzed wax. The chemistry of the aliphatic alcohols will first be 

 considered, followed by an examination of the sterols. 



a. Aliphatic Alcohols, (a) Distribution. Lower alcohols are readily pre- 

 pared in pure form, and their properties are well known. Alcohols lower 

 than octanol (caprylyl) alcohol are ordinarily not found as components of 

 waxes. The higher members of the series, such as ceryl alcohol, CH3- 

 (CH2)24CH20H, and melissyl alcohol, CH3(CH2)26CH20H, are not known 

 with certainty to exist, as is frequently reported; the preparations of 

 these alcohols may actually be mixtures of several even-numbered homo- 

 logues rather than a single homogeneous product. Chibnall et al.^ have 

 proposed an important revision in nomenclature to cover such discrepan- 

 cies. For example, they propose that such mixtures of alcohols should be 

 referred to as C26+C28+C30 alcohols rather than by specific names. Table 

 1 gives the formulas and melting points of some of the common saturated 

 monatomic aliphatic alcohols. 



2 R. S. McKinney and G. S. Jamieson, Oil & Soap, 13, 289-292 (1936). 



3 A, C. Chibnall, S. H. Piper, A. Pollard, E. F. Williams, and P. N. Sahai, Biochem. 

 J., 28, 2189-2208 (1934). 



