Laser Flash Photolysis of Chloranil in Solution

Chloranil (2,3,5,6-tetrachloro-2,5-cyclohexadiene-1,4-dione; C) in deoxygenated acetonitrile shows transient absorptions which are assigned to the radical anion and to the triplet 3C*. The absorption due to rises ‘instantly’ during the 12 ns laser flash and then more gradually in a time of μs. This observation is explained as electron capture from neat acetonitrile by photoexcited C taking place from both its singlet and triplet states with rate constants estimated as 109 and 104 s−1M−1, respectively.