Conformational Selectivity in the Solid-State Photochlorination of Cyclopropane

Article abstract of DOI:10.1021/j100115a030

The solid-state free-radical chain reaction of chlorine with cyclopropane has been investigated with the use of pulsed UV laser photolysis and transmission FTIR spectroscopy.The photochemical quantum yield for an equimolar mixture of the two reagents prepared as a thin film by vapor deposition at 77 K is 52 +/- 8.Samples prepared at this temperature form the anti,anti conformer of 1,3-dichloropropane as the initial reaction product, even when the photolysis is carried out at temperatures as low as 10 K.However, selective formation of the gauche,gauche conformer is observed in the early stages of photolysis for samples that are prepared and photolyzed at 10 K.Continued photolysis of the 10 K sample leads to a sudden burst of reactivity (microexplosion) in which HCl and chlorocyclopropane are formed in addition to distributions of 1,3-dichloropropane conformers.The results indicate that the control of conformational selectivity in this reaction is governed by the influence of temperature and sample density on elementary steps in the reaction mechanism.