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 of the hydrogens of ammonia have been replaced by organic 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 



II i 



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=CH V 



;>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 : 



CH CH 



/ \ / \ 



CH CH CH CH 



II I + HC1 -> || I 



CH CH CH CH 



vy vy 



N N 



/ \ 



H Cl 



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. 

 CH 2 CH 2 



/ \ / \ 



CH,, CHg Ch 2 CHg 



CH 2 CH 2 CH,, CH 2 



\ / \ / 



NH N H 



/ \ 



H Cl 



Piperidine Piperidine hydrochloride 



