Isotopic testing of a mechanistic point in photosensitized epoxidation

✍ Scribed by Paul D. Bartlett; Johannes Becherer

• Book ID: 104245943
• Publisher: Elsevier Science
• Year: 1978
• Tongue: French
• Weight: 238 KB
• Volume: 19
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)94918-4

✦ Synopsis

Since 1974, many cases have been reported in which photo-epoxidation competes with the usual reactions of singlet oxygen! influenced by the nature and concentration of the sensitizer 2 , the solvent 1,2,3 3 2 , substrate , additives , and wavelength of light used.

2 The cleanest photosensitized epoxidation occurs with 4 a-diketones , which often lead to high yields of epoxide with no sign of the production of singlet oxygen, but with substantial attendant destruction of the sensitizer.

In speculating on the mechanism of photosensitized epoxidation, it was reasonable to begin with the possible biradical-forming reactions between triplet excited ketone and either triplet oxygen or ground-state olefin.

Scheme 1 shows several such possibilities, according to whether the ketone /O' RzC