CHEMISTRY OF ALKALOIDS 145 



to note that an alkaloid rarely exists alone in a given plant, but is accompanied 

 by several others. For example, aconitin, as extracted from the roots of the 

 aconite plant, Aconitum napellus, contains nine alkaloids ; in the extract from 

 poppies, called opium, upwards of seventeen alkaloids have been separated and 

 studied; in the so-called chinchona or Peruvian bark extracts, some thirty- 

 three distinct alkaloids have been isolated; strychnin is accompanied by brucin 

 in Strychnos ignatii, or Saint Ignatius bean. 



CLASSIFICATION OF THE ALKALOIDS. 



Owing to the basic character of the alkaloids, and the fact that they always 

 contain nitrogen, it was suggested that they were connected with ammonia in 

 some manner, and if so, that they might be readily broken down by distilling 

 them with potassium hydroxid or caustic potash. They were regarded as de- 

 rived or at least connected with ammonia. Hoffman, who added much to our 

 knowledge of the amin compounds, considered that they were of the ammonia 

 tvpe and were tertiary amins. In attempting to find some reaction characteris- 

 tic of the amins, Gerhardt and others, heated the alkaloids with caustic potash, 

 but were unsuccessful in obtaining any results that showed that their basic 

 character was due to this structural cause, although some of them do possess 

 some properties resembling the amins. Others more closely resemble the am- 

 monium compounds. Products obtained by heating some of the alkaloids with 

 potassium hydroxid and distilling the volatile products were found to be the 

 same as were obtained from the destructive distillation of bones. Later, 1834, 

 a study of bone oil by Runge led to the separation of a pure compound which 

 was shown to have the formula C 5 H.N, known as pyridin. This was later shown 

 to be a cyclic (hetero-cyclic) compound, like benzene, one group "CH" being 

 substituted by nitrogen, i. e., trivalent nitrogen. A number of alkaloids have 

 been shown to be constructed on this nucleus by substituting various hydrocarbon 

 groups and are known as the pyridin alkaloids. 



Among the pyridin alkaloids and derivatives from them are nicotin, coniin, 

 atropin, cocain. The study of the alkaloids by noting the action of potassium 

 hydroxid proved to be a fruitful one. In 1842, Gerhardt obtained a compound 

 from the destructive distillation of quinine that was a new substance. This was 

 named quinolin because of its origin from this alkaloid. It was later shown to 

 be structurally composed of a benzene and a pyridin nucleus joined by two atoms 

 of carbon in common; the further complexity is due to substituting in this 

 nucleus. Most of the alkaloids are esters and are consequently quite readily 

 separated into the two parts of such compounds namely the acid and basic parts. 

 A study of these constituent parts gives the complete facts as to the structure 

 of the original compound. The esters may be decomposed by acids, alkalis, and 

 water. 



The nucleus quinolin has been found in quinin, cinchonin, cinchonidin, strych- 

 nin, and brucin, and hence these compounds are known as the quinolin alka- 

 loids. 



THE ISO-QUINOLIN GROUP. 



This group of alkaloids have a nucleus isomeric with quinolin known as the 

 quirolin group. Like the quinolin group, iso-quinolin has the empirical formula* 

 C 9 H 7 N. The difference between this base and quinolin, so far as structural 

 constitution is concerned, appears in the position of the atom of nitrogen. Not 



