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Short Paper | Regular issue | Vol 83, No. 3, 2011, pp.619-625
Published online, 8th February, 2011
DOI: 10.3987/COM-10-12112
Photochemical Reaction of 4,7-Dimethylbenzofurazan Using Laser

Akira Mori, Yoshiteru Mikami, Hiroaki Saito, Koji Kobayashi, Shinichi Miyairi, Hisashi Ohshima, and Tohru Takabatake*

*College of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi-shi, Chiba 274-8555, Japan

Abstract

4,7-Dimethylbenzofurazan 1 was more reactive than other dimethylbenzofurazans, methylbenzofurazans and benzofurazan for short duration irradiation using a Xe lamp (Pyrex filter). Compound 1 was transformed by irradiation with the third harmonic of a Quanta-Ray Nd:YAG laser (355 nm) into (2Z,4Z)-2,5-dimethylhexa-2,4-dienedinitrile monoxide 2 in CDCl3 at room temperature in excellent yield. With increasing temperature, the isomeric opened form compound 2 is thought to be thermally reverted to the original benzofurazan structure. The rate constant for this recyclization of 2 to 1 using CHCl3 at 293 K was 1.16 x 10-5 s-1. Irradiation of 1 in CDCl3 yields photoproduct compound 2 with a quantum yield of 0.48, and a chemical yield of 99%. The yield of this photoreaction was dependant on the laser power and exposure time.