Isomeric Product Distributions from Solid-State Chain Reactions and Low-Temperature Microexplosions of Acetylene and Chlorine

Article abstract of DOI:10.1021/j100192a042

Free-radical chain reaction of acetylene and chlorine is initiated by pulsed ultraviolet photolysis of disordered solid films of these reagents at 10-60 K.The product (identified by FTIR spectroscopy) is a mixture of Z (cis) and E (trans) isomers of 1,2-dichloroethene.At 60 K in an equimolar mixture of reagents the photochemical quantum yield is 25 +/- 4; the isomeric product distribution is / = 10.2 +/- 1.5.At 10-30 K samples exhibit a sudden burst of reactivity (a microexplosion) after exposure to a cumulative laser fluence of 1-12 mJ/cm² at 337 nm.The isomeric product distribution under these conditions is 2.9 +/- 0.4.The results demonstrate that reaction conditions during these microexplosions are characterized by high temperature and high mobility associated with transient liquefaction of the sample.