The photoinduced reaction of 2-iodothiophene in solutions of n-heptane, dichloromethane and methanol

Abstract

The photoinduced reaction of 2-iodothiophene in n-heptane, dichloromethane and methanol was studied at room temperature from experiments carried out with degassed solutions. The photoproducts of the reaction were mainly thiophene and small amounts of iodine in all three solvents used. The concentration of 2-iodothiophene decreases throughout photolysis, following a first-order rate law and the pseudo-first-order rate constants were determined in the three solvents used. The photochemistry of the system was quantified determining the quantum yields of 2-iodothiophene consumption and thiophene formation in n-heptane solutions. The results show that under the experimental conditions of this research, products deriving only from the reaction of the thienyl radical were observed. To support the experimental results, calculations were performed of the ionization potential of the thienyl radical, electron affinity of the iodine atom and free energy of solvation of the corresponding iodide and carbocation in the different solvents used. Copyright © 2010 John Wiley & Sons, Ltd.