354 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



Atropine or dl-Hyoscyamine. C 17 H 23 O 3 N. 



Atropine (or daturine) is found in the deadly nightshade, Atropa 

 belladonna, in henbane, Hyoscyamus niger, and together with /-hyo- 

 scyamine in Datura stramonium. 



The juice (i litre) obtained by pressing the plant is made alkaline with 

 potash (4 gm.) and extracted with chloroform (25 c.c.). The chloroform extract 

 is evaporated and the residue is treated with dilute sulphuric acid which dis- 

 solves the base. On adding potassium carbonate to the acid solution the 

 atropine is precipitated and is crystallised from alcohol. 



Atropine is a white crystalline solid separating in prisms from 

 dilute alcohol. It melts at 115, is almost insoluble in water but 

 is easily soluble in alcohol, ether and chloroform. It is extremely 

 poisonous, from '05 -'2 gm. being a lethal dose. It is a strong base 

 and forms salts with acids which are easily soluble in water. The 

 sulphate is most commonly used in medicine for dilating the pupils 

 and other purposes. 



Atropine may be tested for as follows : on evaporating a small 

 quantity with a drop of fuming nitric acid a yellow residue is left. 

 This turns violet, changing to red, on adding a drop of alcoholic potash. 



Constitution. 



On hydrolysis by boiling with baryta, atropine is converted into 

 tropine and tropic acid. 



Tropic acid is a-phenyl-/3-hydroxypropionic acid. 



Tropine has been shown to be the N-methyl derivative of a 

 7-hydroxy-piperidine nucleus containing two extra 

 methylene groups, or as a hydroxy derivative of 

 a combined piperidine and pyrrolidine nucleus to 

 which a methyl group is attached at the nitrogen 

 atom. 



Atropine is the tropic acid ester of tropine : 



HOOOCH-CH 2 OH 

 CH 



HC 



and it has been synthesised from its constituents. 



