Anomalous changes in the concentration of paramagnetic centers upon thawing the radiolyzed acetaldehyde hydrogen cyanide system

An anomalous change in the concentration of paramagnetic centers was found in the course of warming an acetaldehyde-hydrogen cyanide system with a 1 : 3 molar ratio of reactants radiolyzed at 77 K. A small decrease (similar t o 10%) in the total concentration of paramagnetic centers was observed upon warming the system above 77 K. Then, in the region 110-140 K, their concen tration increased almost twofold through an increase in the amount of H2C=( N) over dot radicals; their concentration monotonically decreased upon a fu rther increase in temperature. The increase in the concentration of paramag netic centers was supposedly related to the recombination of [HCN...H](+) c ations stabilized upon radiolysis of HCN with thermally released electrons to form an additional amount of H2C=(N) over dot radicals.