Free-radical addition to olefins. Part 26. - Kinetics of the addition of trifluoromethyl radicals to acetylene and substituted acetylenes

Amr El Soueni, John M. Tedder*, John C. Walton

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Absolute Arrhenius parameters have been determined for the addition of trifluoromethyl radicals to acetylene, propyne, but-2-yne, 1,1,1-trifluoropropyne and hexafluorobut-2-yne by a competitive method using the previously determined Arrhenius parameters for the addition of trifluoromethyl radicals to ethylene as standard. Xα kX/kC2H2 (164 °C) Eact/kcal mol-1 logA/dm3 mol-1 s-1 ↓HC≡CH 1 5.00±0.30 8.70 ±0.25 ↓HC≡CH3 5.2b 3.45±0.28b 8.63±0.08b ↓HC≡CCF3 0.49 5.10±0.26 8.44±0.13 ↓CH3C≡CCH3 2.0 4.36±0.30 8.68±0.16 ↓CF3C≡CH 0.043 6.61±0.33 8.13±0.18 ↓CF3C≡CCF3 0.068 5.86±0.38 7.95±0.06 1 cal ≡ 4.1845 J. a Arrow shows site of attack; b sum of attack at both sites in propyne. Both the activation energies and the A-factors are larger than those for the addition of trifluoromethyl radicals to similarly substituted olefins. As a result of these opposing effects the rates of addition are similar.

Original languageEnglish
Pages (from-to)89-100
Number of pages12
JournalJournal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
Volume77
Issue number1
DOIs
Publication statusPublished - 1 Dec 1981

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