Bond strengths of ethylene and acetylene

• Published in: Journal of the American Chemical Society Vol. 112; no. 15; pp. 5750 - 5759
• Main Authors: Ervin, Kent M, Gronert, Scott, Barlow, S. E, Gilles, Mary K, Harrison, Alex G, Bierbaum, Veronica M, DePuy, Charles H, Lineberger, W. C, Ellison, G. Barney
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.07.1990
• Subjects: ACETYLENE; ALKENES; ALKYNES; Atomic and molecular physics; CHEMICAL BONDS; DATA; DATA ANALYSIS; DISSOCIATION ENERGY; ELECTRON SPECTROSCOPY; ENERGY; ETHYLENE; Exact sciences and technology; EXPERIMENTAL DATA; HYDROCARBONS; INFORMATION; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; KINETICS; MEASURING INSTRUMENTS; MEASURING METHODS; Molecular properties and interactions with photons; NUMERICAL DATA; ORGANIC COMPOUNDS; PHOTOELECTRON SPECTROSCOPY; Physics; SPECTROSCOPY 400201 > Chemical & Physicochemical Properties; Molecules; Chemical bond; Photoelectron spectrum; Experimental study; Thermodynamic properties; Molecular dissociation; Organic compounds
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00171a013

Negative ion photoelectron spectroscopy and gas-phase proton transfer kinetics were employed to determine the CH bond dissociation energies of acetylene, ethylene, and vinyl radical: D{sub 0}(HCC-H) = 131.3 {plus minus} 0.7 kcal mol{sup {minus}1}, D{sub 0}(CH{sub 2}CH-H) = 109.7 {plus minus} 0.8 kcal mol{sup {minus}1}, and D{sub 0}(CH{sub 2}C-H) = 81.0 {plus minus} 3.5 kcal mol{sup {minus}1}. The strengths of each of the other CH and CC bonds in acetylene and ethylene and their fragments were derived. The energy required to isomerize acetylene to vinylidene was also determined: HC{triple bond}CH {yields} H{sub 2}C{double bond}C: {Delta}H{sub isom,0} = 47.4 {plus minus} 4.0 kcal mol{sup {minus}1}. As part of this study, proton transfer kinetics in a flowing afterglow/selected-ion flow tube apparatus were used to refine the acidities of ethylene, acetylene, and vinyl.