264 NITROGEN BASES 



secondary, and tertiary amines, according as one, two, or three 



of the hydrogens of ammonia have been replaced by organic 



radicles. 



Tertiary amines are also known in which the nitrogen 



atom takes part in the formation of a ring, as, for example, in 



pyridine — 



CH 



/ \ 

 CH CH 



CH CH 



\ /- 



N 



which may be regarded as being derived from ammonia by the 



replacement of three atoms of hydrogen by the five carbon ring — 



— CH=CHv 



);CH 

 =CH— CH/^ 



Pyridine, being a substituted ammonia, can form salts by 



changing the valency of its nitrogen atom from three to five, 



as follows : — 



H CI 



Pyridine Pyridine hydrochloride 



Secondary amines containing a nitrogen atom in the ring 

 are also known. 



Thus, when pyridine is reduced by nascent hydrogen, six 

 atoms of hydrogen are added on, and a substance known as 

 piperidine is produced ; this substance is a secondary amine, 

 since it now has a hydrogen atom attached to its nitrogen. 

 Like pyridine, it can also form a salt with hydrochloric acid. 



/ \ / \ 



I t -> I 1 



CH2 CHij CH„ CH2 



\ / \" / 



NH N — H 



/ \ 

 H CI 



Piperidine Piperidine hydrochloride 



