Other substituents attached to nitrogen

Pyridine iV-sulfides are known only in the form of their derivatives. Thus, 1-arylthiopyridinium cations (from pyridine and sulfenyl chloride) react with KCN to form ArSCN and pyridine (81CC703). Pyridine-sulfur trioxide is a mild sulfonating reagent, used for sulfonation of furan and pyrrole. 

Pyridine-halogen complexes (73) dissociate on heating halogen is lost so readily that these compounds act as mild halogenating agents toward phenol or aniline, for example (see Section 3.2.1.3.8). 

The complexes formed with boron trihalides are decomposed to pyridine by boiling water. Complexes with other Lewis acids behave similarly. 

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