The Radiolysis of Cyclopetane

The gamma radiolysis of cyclopentane in the liquid phase at room temperature was investigated. Four major products were observed: hydrogen (Go = 5.35), pentene-1 (Go = 0.74), cyclopentene (Go = 2.97), and cyclopentyl-cyclopentane (Go - 1.29). A kinetic model for the scavenging of ions produced in pairs is presented. Application of the model to electron scavenging by sulfur hexafluoride and octafluorocyclobutane suggests that the ion pair population is distributed over separation distances, y, in a manner well approximated by a y-5/2 function. With this distribution function the scavenging model predicts a region of scavenging efficiency dependent on the square root of the scavenger concentration. The hydrogen yields from fully scavenged cyclopentane solutions of octafluorocyclobutane indicate that the G value for hydrogen that has ionic precursors is 3.4. The isotopic forms of hydrogen from cyclopentane solutions of ND3 show that a hydrocarbon ino intermediate acts as a Bronsted acid toward ND3 to form ND3H+ ions. The decomposition of isotopically mixed ammonium ions has an isotope effect greater than about 2 for the cleavage of an N-H bond compared to an N-D bond. Hydrogen yields from cyclopentane solutions of benzene show at least two distinct intermediates for this product. Below about 1% benzene hydrogen inhibition may involve predominantly the scavenging of cyclopentane positive ions. Above 1% other hydrogen precursors are inhibited; these may be “hot” or thermal hydrogen atoms or neutral excited cyclopentane molecules capable of activation transfer to benzene.