Role of ring-enlargement reactions in the formation of aromatic hydrocarbons.

Ring-enlargement reactions can provide a fast route towards the formation of six-membered single-ring or polycyclic aromatic hydrocarbons (PAHs). To investigate the participation of the cyclopentadienyl (CH) radical in ring-enlargement reactions in high-temperature environments, a mass-spectrometric study was conducted. Experimental access to the CH high-temperature chemistry was provided by two counterflow diffusion flames.