9 2 SCIENCE PROGRESS 



C^H^O . Br 2 , and thus contains one double link in the molecule. 

 The hydroxyl of the secondary group CH . OH can be replaced 

 by chlorine, giving cholesteryl chloride, C^H^Cl, and it reacts 

 readily with acids forming esters, of which the oleate and 

 palmitate occur in blood serum. Besides these the formyl, 

 acetyl, propionyl, and benzoyl derivatives are readily prepared, 

 the reaction with acetic anhydride in particular being so smooth 

 that it has been employed for the quantitative estimation of 

 cholesterine. From what follows it will be seen that the 

 hydroxyl group appears to be situated in a ring and the 

 double link at the end of an open chain of three or four carbon 

 atoms, so that the double link is in the Be, or e£, position to the 

 OH group. Beyond this but little is known of the structure 

 of the cholesterine molecule. The opinion is gaining ground 

 that the body is related to the higher terpenes x and the resin 

 acids, and that it contains probably four reduced rings, being 

 based upon a reduced hydrocarbon, just as abietic acid is 

 now recognised as coming from a reduced methyl isopropyl 

 phenanthrene (Retene). 2 But our knowledge of the structure 

 of the complex terpenes is so slight that even if cholesterine 

 proved to be related to them a great deal of work would be 

 required before we should be in a position to apply their pro- 

 perties and reactions to the solution of the cholesterine problem. 

 An experimental difficulty, too, lies in the great stability of 

 cholesterine. While it readily yields derivatives containing the 

 same number of carbon atoms in the molecule, it can only be 

 broken down by somewhat drastic methods, and the process 

 is accompanied by an enormous wastage of a material which, 

 probably, will always be scarce. Mauthner and Suida, for 

 example, 3 who have made destructive experiments of this kind, 

 obtained a hydrocarbon, Ci 9 Ho8, which, on chlorination and 

 subsequent treatment, gave two bodies — one soluble, the other 

 insoluble, in ether. From 162 grammes of the former, after dis- 

 tillation with lime, only '3 gramme of a body smelling like menthol 

 was obtained, barely enough for a melting point and a single 

 combustion. They have since been engaged upon oxidation 

 experiments which seem more hopeful of results. 



1 Tschirch and Studer, Archiv d. Phar. 241, 542 ; Mauthner and Suida, 

 Monatshefte fur Chemie, 15, 114 ; 24, 173. 



2 Ber. 36, 4200 ; Proc. C. S. 20, 112. 

 Monatshefte fur Chemie, 24, 648. 



3 IV 



