1,4-DICARBONYL-2,5-CYCLOHEXADIENE

The mechanism of the photolysis of [2.2]paracyclophane-1,10-dione (9) was investigated in solution and in argon matrices. The first step of the photolysis involves alpha-cleavage of the cyclophane yielding a di radical 11 which could be trapped by ethanol. In argon at 10 K the dir adical rapidly splits into p-xylylene (10) and 1,4-dicarbonyl-2,5-cycl ohexadiene (7) and therefore was not directly observed by spectroscopi c methods. The bisketene 7 was characterized by comparison of the expe rimental and calculated IR spectrum.