Time-Resolved Infrared Study on the Photochemistry of O-Fluoroformyl- and O-Chlorooxalyl-9-fluorenone Oxime: The Reactivity of the Fluoroformyl Radical in Acetonitrile Solution

摘要

This note describes the photochemistry of O-chlorooxalyl-and O-fluoroformyl-9-fluorenone oxime.The solution photochemistry of both precursors was investigated by time-resolved step/scan FTIR spectroscopy.Experiments on O-chlorooxalyl-9-fluorenone oxime only allowed for detection of CO_2 and bleaching of the precursor,indicating predominant N-O cleavage.The chlorocarbonyl radical,ClCO~(centre dot),was not detected.In contrast,TRIR investigations on fluoroformyl oxime 2 gave evidence for formation of the fluoroformyl radical FCO~(centre dot) (3),which rapidly adds to the solvent acetonitrile,yielding a fluoroformyl-functionalized iminyl radical 4.Its reaction with triplet molecular oxygen,on the other hand,is impeded by an activation enthalpy that has been calculated as DELTA H = 3.2 kcal/mol.