Photochemistry of Iodoform in Methanol: Formation and Fate of the Iso-CHI2-I Photoproduct

✍ Scribed by Patrick Z. El-Khoury; Wai Ming Kwok; Xiangguo Guan; Chensheng Ma; David Lee Phillips; Alexander N. Tarnovsky

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 441 KB
• Volume: 10
• Category: Article
• ISSN: 1439-4235
• DOI: 10.1002/cphc.200900122

✦ Synopsis

Abstract

Ultrafast population and structural dynamics due to the iso__‐CHI~2~‐I isomer product formed upon UV excitation of iodoform (CHI~3~) in solution is monitored by femtosecond transient absorption with deep‐UV through near‐IR probing and picosecond transient resonance Raman spectroscopy.__ Iso__‐CHI~2~‐I is found to be a major photochemical product regardless of excitation wavelength (266 and 350 nm) and choice of solvent (methanol, acetonitrile, and cyclohexane), and is produced in 50 % quantum yield upon 266 nm excitation of CHI~3~ in CH~3~OH. The isomer remains stable up to at least several nanoseconds in C~6~H~12~ and CH~3~CN, but undergoes decay with a 740 ps lifetime in CH~3~OH simultaneously with the formation of an iodide ion. In agreement with the experiments, MP2 calculations suggest that__ iso__‐CHI~2~‐I readily reacts with CH~3~OH via O‐H insertion/HI elimination reactions.__