Kinetics of Elementary Reactions in the Chain Chlorination of Cyclopropane

Abstract

The kinetics of elementary reactions involved in the chain chlorination of cyclopropane are examined using a combination of absolute and relative rate constant measurements and first principles electronic structure calculations. Relative rate methods are used in a smog chamber FTIR apparatus to determine k(Cl + c-C 3 H 6 ) ) (1.15 ( 0.17) × 10 -13 and k(Cl + c-C 3 H 5 Cl) ) (1.06 ( 0.18) × 10 -12 cm 3 molecule -1 s -1 in 10-700 Torr of air, or N 2 , diluent at 296 K. Absolute rate coefficients for the reaction of Cl with cyclopropane are measured between 293 and 623 K by a laser-photolysis/CW infrared absorption method. The data can be represented in Arrhenius form as k(Cl + c-C 3 H 6 ) ) ((1.8 ( 0.3) × 10 -10 cm 3 molecule -1 s -1 )e -(2150(100)/T . To support the experimental investigations, first principles electronic structure calculations are performed. Vibrational spectra of c-C 3 H 5 Cl, c-C 3 H 4 Cl 2 , and c-C 3 H 3 Cl 3 are calculated and are presented. gem-C 3 H 4 Cl 2 is calculated to be the kinetically and thermodynamically most favored dichlorocyclopropane. The experimental observations are consistent with the computational findings.

Relative Rate Studies of the Reactions of Atomic Chlorine with Acetone and Cyclic Ketones

“…, and ab initio data are given in the Appendix; the key result is that the energy of the TS including zero‐point vibrational energy is within 0.5 kJ mol −1 of the reactants so that the predicted activation energy is effectively zero. Given a preexponential factor for Cl + cyclopropane of 1.8 × 10 −10 cm 3 molecule s −1 , we expect that k 6 for cyclopropanone, which has only two methylene groups rather than three, is about 1.2 × 10 −10 cm 3 molecule s −1 . This is marginally larger than k 2 , about a factor of 20 greater than an SAR extrapolation, and about a factor of 60 greater than k 1 .…”

Single photon ionization of van der Waals clusters with a soft x-ray laser: (SO2)n and (SO2)n(H2O)m

“…Multiphoton ionization of ͑SO 2 ͒ n by femtosecond laser excitation shows much more extensive fragmentation, with ͑SO 2 ͒ n−1 SO + features being more intense than parent ͑SO 2 ͒ n + features. [19][20][21] One advantage of femtosecond versus nanosecond multiphoton ionization is that up pumping to the ion state typically precludes dissociation reactions for the neutral cluster during the ultrafast ionization process. Apparently, single photon, even 26.5 eV, ionization imparts much less final energy "excess energy" over that required for vertical ionization.…”

Recent advances in the syntheses, transformations and applications of 1,1-dihalocyclopropanes

“…50,51 For phase transfer catalysts of the same anion, a smaller quaternary ammonium cation showed larger reactivity and the reason for this behaviour was attributed to the interfacial reaction mechanism where the reaction rate is highly dependent on the concentration of the catalyst at the interface. 53 The absolute and relative rate constants were measured and computationally confirmed. 52 The kinetics of chain chlorination of cyclopropanes was also studied.…”