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The effect of p H on the course of the photoreaction of 2,4‐pyridinedicarbonitrile with benzophenone in aqueous 2 propanol: Reduction vs substitution
Author(s) -
Caronna Tullio,
Morrocchi Sergio,
Vittimberga Bruno M.
Publication year - 1990
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570270635
Subject(s) - chemistry , benzophenone , protonation , aqueous solution , medicinal chemistry , photochemistry , kinetics , one electron reduction , ion , propanol , organic chemistry , ethanol , electrochemistry , physics , electrode , quantum mechanics
The photoinitiated reactions of 2,4‐pyridinedicarbonitrile ( 1 ) and benzophenone in neutral, acidic, and basic 3:1 2‐propanol‐water and the kinetics of disappearance of 1 , have been studied. Pyridinyl radical anion forms as an intermediate by an electron transfer. In acidic solution substitution of the cyano group in the 2 position and in the 2 and 4 positions with diphenylmethanol occurs. In neutral medium both substitution at the 2‐position and reduction, in which the cyano group at the 4 position is replaced by hydrogen, are observed. In basic solution in which protonation of the radical anion is not likely, only reduction occurs. The rates of formation and relative yields of these products depends on the p H of the solution. A mechanism is discussed.