104 



CYCLOSES, CHOLESTEROL AND CHOLIC ACID 



of the sulphuric acid, is not absolutely to be relied upon, since similar 

 reactions (differing from one another, however, in the absorption- 

 spectra of the fluids produced) are yielded by a variety of substances, 

 for example proteins, oleic acid, phospholipins, amyl alcohol and 

 morphine. 



Neuberg-Rauchwerger's Reaction. Also given by cholesterol, which 

 see. 



The structure of cholic acid has not yet been fully elucidated, but it 

 appears to be definitely established that it is a derivative of the hydro- 

 aromatic series. The decomposition-products resulting from the 

 variety of procedures contain fractions which are closely related to 

 products which are similarly obtained from other hydro-aromatic 

 derivatives, such as cholesterol, turpentine and camphor, and the 

 identification by Panzer of hydroxy-hexahydro-phthalic acid: 



OH 



H 2 C 



H 2 C 



\/ 

 c 



/\ 



COOH 

 / 



\ 

 CH 2 



CH S 

 / 



CH 



COOH 



among the oxidation-products of cholic acid leaves very little room for 

 doubt that hydro-aromatic nuclei exist preformed in the undecomposed 

 molecule. Apart from these inferences, however, it is known that 

 cholic acid contains one carboxyl-group and two primary and one 

 secondary alcohol-groups united to a hydrocarbon-complex which 

 contains cyclic linkages. The formula may therefore be written: 



C 2 oH 



fCHOH 

 CH 2 OH 

 31 CH 2 OH 

 I COOH 



A related acid which is found in small amounts in ox-bile and also in 

 gall-stones is Choleic Acid, which differs from cholic acid in its per- 

 centage composition ^JLoCX) and in its relative insolubility in 

 alcohol. It yields a blue compound with iodine and also gives Ham- 

 marsten's reaction with hydrochloric acid. Desoxycholic Acid, how- 

 ever, which also occurs in bile and in gall-stones yields neither of these 

 reactions although it is isomeric with choleic acid. 



