T H E J O U R N A L
OF
PHYSICAL CHEMISTRY Registered in
U.8.Patent Ofice
@ Copyright, 1QY1, by the American Chemical Xociety
VOLUME 75, NUMBER 25 DECEMBER 9,1971
The Reactions of Recoil Tritium Atoms with 1-Butene and cis-2-Butene. Average Energy of the Addition Reaction’
by Richard Kushner and F. S. Rowland* Department of Chemistry, University of California, Irvine, California OS664 (Received June 1 , 1071) Publication costs assisted by Division of Research, U . 8.Atomic Energy Commission
Consistent yields of propylene-t and CH2=CHT are found from recoil tritium reactions with 1-butene in 02-scavenged, H2S-scavenged, and unscavenged experiments. A large yield of n-CdHBT in the H B system confirms that substantial yields of butyl-t radicals are collisionally stabilized prior to decomposition to the smaller olefinic products, Similar observations are made with cis-2-butene as the parent molecule. Pressuredependent studies show a complementary relationship between the yields of the stabilization product (nC4HeT)and the decomposition products (CWz=CHT and CH2TCH=CH2 from 1-butene; CHaCH=CHT from cis-%butene). Pressure-dependent decomposition of the labeled parent molecules is also observed. From calculated rate constants for butyl-t radical decomposition, the median kinetic energy of tritium atoms undergoing addition to the olefinic positions is estimated as 70% 02.
Introduction Basic studies of the reactions of energetic tritium with saturated hydrocarbons have demonstrated that most hot reactions are either abstraction or substitution processes, as in (1) and ( 2 ) . With olefins, addition to
T*
+
T*+RH--,HT+R (1) RX -+ RT* X (X = H, CHa, etc.) (2)
+
the double bond, as in (3), is also an important reac-
T*
+ >C=C
CT-C
