[ 6o CHEMISTR V FOR A GRIC UL TURAL STUDENTS 



XXXIV. AMMONIA DERIVATIVES— ALKALOIDS 

 AND AMIDES 



In the foregoing studies it has been observed that organic 

 compounds may be regarded as simple inorganic compounds 

 in which an element is replaced by an organic radicle, i.e. a 

 group of elements, of which carbon is one, which plays the part 

 of an element. Thus alcohol, C2H5.OH, is water, H.OH, in 

 which hydrogen has been replaced by ethyl. Acetic acid, 

 H.C2H3O2, is hydrochloric acid, H.Cl, in which the acetic 

 radicle has been substituted for chlorine. Similarly there is a 

 group of organic compounds which are regarded as substituted 

 ammonias, i.e. ammonia, NH3, in which one or more atoms of 

 hydrogen are replaced by organic radicles. These compounds 

 are termed amines and alkaloids. They are alkaline in re- 

 action, like ammonia, and combine with acids forming salts. 



An important amine is trimethylamine, N(CH3)3, the sub- 

 stance to which the fishy smell of herring brine is due. 

 Pyridine — NC5H5 — is a volatile base of powerful odour pro- 

 duced in the distillation of coal, and usually found as the 

 sulphate in small quantities in commercial sulphate of ammonia. 

 Alkaloids frequently exist in plants, and to them the medicinal 

 or toxic properties of plants are often due. Thus quinine, 

 an alkaloid found in cinchona bark, atropine or atropia in 

 belladonna, aconitine in aconite, morphine or morphia in 

 opium, and nicotine in tobacco, are the active constituents 

 of these plants. 



Mix some sulphate of quinine with water in a stoppered 

 separatory funnel. Note that this salt is almost insoluble. 

 Now add a little dilute sulphuric acid to convert the sulphate 

 into the soluble acid sulphate, and to the clear solution thus 

 obtained add solution of caustic soda in order to precipitate the 

 alkaloid itself. Shake the white mixture with ether until the 

 alkaloid is completely dissolved in the ether, run off the water, 



