High‐energy kinetic study of chemically activated 1,1‐dichlorocyclopropane

Abstract

Abstract1,l-Dichlorocyclopropane has been produced by addition of CHz('A1) to 1,l-dichloroetbylene. CHZ('A1) was generated by the photolysis of ketene at 277-334 nm. The 1,l-dichlorocyclopropane was formed in a chemically activated state, had an energy content between 386 and 400 kJ/mol, and reacted in two parallel channels to 2,3-dichloropropene and 1,ldichloropropene. 1,l-Dichloropropene was also formed directly by insertion of CHZ('A1) into the CH bond of 1,l-dichloroethylene. As secondary reactions elimination of HCl from chemically activated 2,3-dichloropropene occurred with 3-chloropropyne and chloroallene as products. In some of the experiments perfluoropropane was added as an inert gas. The apparent rate constants for the isomerization and elimination reactions are reported. The results of RRKM calculations including distribution functions for the activated 1,l-dichlorocyclopropane and a step-ladder model for the deactivation verify the proposed reaction scheme.

Kinetic study of chemically activated chlorocyclopropane

“…A full analysis of the oxygen-free system is complicated, however, by the fact of rapid collisional deactivation of CH2(1A1) to the CH2(3B1) state. Our observations are in contrast to the ones made in our study of the CH2/CH2CCl2 system where CH2(3B1) rates appear to be slower or competitive channels faster [3]: no products were detected at 366 nm without oxygen addition.…”

“…This proves that different amounts of energy are still present in the primary products 3-chloropropene, cis-, and trans-l-chloropropene at the time of secondary reaction. As stated in our earlier paper [3], the available pieces of information were not considered to be a sound basis for the performance of a RRKM calculation for the secondary decomposition channels. The straight lines in Figures 5 and 6 indicate that the isomerization reaction allene +.…”

“…As in ref. 3, which should be consulted for further details, two refinements were made in the calculations: a stepladder deactivation model was used and an energy distribution function for the activated molecules was computed. This required the construction of three activated complex models, two for the isomerization channels and one for the decomposition reaction of CCP into CH2 plus chloroethene.…”

Survey of the heats of formation of three-membered-ring species

“…The general observation that, despite their structural simplicity, three-membered ring carbocyclic compounds are nontrivial to analyze is illustrated by the first compound in Table I. The heat of formation of hexafluorocyclopropane was found8 by interrelating the ionization potential of this species and the appearance DRV c3h40 cyclopropane 16 (4) DRV C3H5Br bromocyclopropane 27.6 (4.4) 21DRV c3h6 cyclopropane (la) 53.5 (0.5) 5 c3h7n cyclopropylamine 45.8 (0.5) 7 77.0 (0.7) 150.5 (0.9) 5 c9h12 bicyclo[6.1.0]nona-2,4-diene (23) 210 DRV 258 DRV c9h12 bicyclo[6.1.0]nona-3,5-diene (24) 25.9 (8.8) 76 ^28^48^* (6/3)-methoxy-3,5-cyclocholestane (41) [-628.0 (5.5)]…”

Experimental study on the reactions of vibrationally excited 1,1‐difluorocyclopropane

“…The isomerization of cyclopropane ranks as a prototype of unimolecular reactions [l]. Various studies on alkyl-and halogenosubstituted derivatives were performed subsequently, often using chemical-activation methods [2,3]. Many of the earlier investigations were based on the assumption of an analogy in reaction behavior between the substituted compounds and cyclopropane itself [4].…”