CHAPTER XV 



CHEMISTRY OF AttKAIX)IDS. 

 PROF. A. A. BENNETT 



The term alkaloid is a relic of an early method of nomenclature, namely, the 

 method of naming substances without reference to their fundamental properties. 

 For example, the name, oil of vitriol, does not describe sulfuric acid except that 

 it has a deceptive resemblance to an oil, and was originally produced from green 

 vitriol. The word alkaloid literally signifies a substance resembling an alkali. 

 They do form salt-like compounds with acids but here the likeness as to speci- 

 fic properties ends. 



It is only about one hundred years since the facts as to alkaloids began to 

 accumulate. The first separation of these compounds was made in 1803 by 

 Derosne but their basic character was not noted until three years afterwards 

 by Serturner while studying opium. Before this time many plant extracts were 

 known to contain some very active compounds usually called principles, but their 

 isolation and the determination of their composition and properties date from 

 the first quarter of the nineteenth century. 



The first alkaloid that was prepared and reported according to the usual 

 method of procedure of the chemists, namely, obtaining the pure compound and 

 then determining its chief properties, was morphin. Although this was done 

 about 1806 it was not until some eleven years afterwards that the report at- 

 tracted the attention of chemists, sufficiently to start the investigation of other 

 substances for the presence of similar compounds with the result that new com- 

 pounds of this class have been separated and described each year since this date. 

 The property that especially characterised these compounds was their basicity, 

 i. e., they formed salt-like compounds with acids, although they were but weakly 

 alkaline to the usual indicators of alkalinity. 



COMPOSITION AND GENERAL PROPERTIES OF ALKALOIDS. 



The alkaloids all contain nitrogen, carbon and hydrogen and all but two of 

 them contain oxygen. A large proportion of the alkaloids are non-volatile, 

 solid, crystalline compounds, while a few are volatile liquids but contain no 

 oxygen. They are generally insoluble in water but are generally soluble in 

 alcohol and possess varying degress of solubility in ether, chloroform, amylic 

 alcohol and carbon disulfid. These latter facts of solubility are often made use 

 of to separate the alkaloids from each other, and from other substances. The salt- 

 like compounds, on the other hand, generally possess a measurable degree of 

 water solubility but not in the other solvents mentioned. They differ from the 

 true alkalis, like potassium and sodium hydroxids, in the fact that the molecules 

 of acids and alkaloids unite with each other without forming other products. 

 In this property, they resemble ammonia, HN 3 , when it forms such salts as am- 

 monium chlorid, NH 3 , HC1 or NH 4 C1. However, this property does not char- 

 acteristically belong to the so-called true alkaloids, since the amins, purin bases, 



