Spectroscopic Studies on Photochemical Formation of o-Xylylene in Solution

The photochemical formation of o-xylylene is studied by two-pulse fluorescence and transient absorption spectroscopy. o-Xylylene is produced by photolysis of α,α‘-dichloro-o-xylene, α,α‘-dibromo-o-xylene, α,α‘-bis(trimethylstannyl)-o-xylene, and 2-indanone at 266 nm in room-temperature cyclohexane solution. On excitation at 308 nm, the fluorescence of o-xylylene is observed with a maximum at 460 nm and a lifetime of 9.3 ± 0.5 ns. The absorption of o-xylylene is obtained with a maximum at 370 nm. The formation of o-xylylene from α,α‘-dichloro-o-xylene occurs, by 266-nm two-photon excitation, with an apparent yield of 0.30 ± 0.08 at a fluence of 40 mJ cm-2. Its formation from 2-indanone proceeds, by 266-nm one-photon excitation, with a rate of (1.4 ± 0.1) × 107 s-1 and a yield of 0.90 ± 0.08.