THE ALKALOIDS 357 



Quinine is very similar in constitution to cinchorthie and is methoxy- 

 cinchonine : 



CH 3 



Strychnine. C 21 H 22 O 2 N 2 . 



Strychnine is the poisonous alkaloid of the seeds of Strychnos nux 

 vomica, in which it is present together with brucine. 



The powdered seed is extracted with hot dilute alcohol. The alcoholic 

 solution is evaporated and the aqueous remainder is treated with lead acetate 

 which precipitates tannin, proteins, etc. The excess of lead is removed by 

 treatment with hydrogen sulphide and the filtrate from the lead sulphide is 

 freed from hydrogen sulphide. Magnesia is added to precipitate the alkaloids 

 which are filtered off after standing. The mixture of brucine and strychnine 

 is separated by alcohol which dissolves the brucine. The strychnine is puri- 

 fied by crystallisation from alcohol. 



Strychnine crystallises in colourless prisms which melt at 284. It is very 

 slightly soluble in water and its solutions have a very bitter taste. It is a 

 weak base and forms salts with acids. 



Though it contains 2 nitrogen atoms it is only a monacid base and com- 

 bines with only i molecule of methyl iodide. 



Strychnine gives the following reaction by which it may be detected : 



On treating a small quantity of strychnine or a strychnine salt with con- 

 centrated sulphuric acid in a porcelain basin and on adding a small amount 

 of powdered potassium bichromate, a violet solution is produced which be- 

 comes red and then yellow. 



The constitution of strychnine has not yet been definitely determined, 

 but it is a derivative of quinoline. 



Brucine. C 21 H 20 (OCH 3 ) 2 O 2 N 2 . 



Brucine is present with strychnine in the seeds of nux vomica. 



Preparation. 



The alcoholic solution, in which the brucine has dissolved in the separa- 

 tion from strychnine, is evaporated to dryness. The residue is dissolved in 

 dilute acetic acid and this solution is evaporated so as to remove the strych- 

 nine which is also contained in it The strychnine separates out on eva- 

 poration and is filtered off, the strychnine acetate being an unstable salt. 

 The brucine acetate is dissolved in water and the brucine is precipitated by 

 adding caustic soda. It is crystallised from alcohol. 



