Halgren, Thomas A. and Roberts, John D. and Horner, John H. and Martinez, Felix N. and Tronche, Christopher and Newcomb, Martin (2000) Kinetics and Equilibrium Constants for Reactions of α-Phenyl-Substituted Cyclopropylcarbinyl Radicals. Journal of the American Chemical Society, 122 (13). pp. 2988-2994. ISSN 0002-7863. doi:10.1021/ja991114h. https://resolver.caltech.edu/CaltechAUTHORS:20151001-101404659
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Abstract
Laser-flash photolysis methods were used to determine Arrhenius functions for cyclizations of the 4,4-diphenyl-3-butenyl (2) and trans-4-phenyl-3-butenyl (5) radicals to the 1,1-diphenylcyclopropylcarbinyl (1) and 1-phenylcyclopropylcarbinyl (4) radicals, respectively. At 20 °C, the cyclization rate constants are 1.7 × 10^7 and 5.4 × 10^6 s^(-1). Equilibrium constants for the two processes were estimated and evaluated with thermochemical data and via computational methods, and Arrhenius functions for the ring-opening reactions of the cyclopropylcarbinyl radicals were calculated. The cyclization reactions of 2 and 5 are strongly enthalpy controlled. Production of radicals 1 and 2 from the corresponding tert-butylperoxy esters in the presence of Et_3SnH gave diphenylcyclopropylmethane and 1,1-diphenyl-1-butene from H-atom trapping of radicals 1 and 2 and 4-phenyl-1,2-dihydronaphthalene which derives from the product radical formed by addition of the radical moiety in 2 to the cis-phenyl group. Rate constants for the latter cyclization of 2 and for reactions of radicals 1 and 2 with Et_3SnH were obtained from the indirect kinetic studies.
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Additional Information: | © 2000 American Chemical Society. Received April 8, 1999. Revised Manuscript Received February 2, 2000. Publication Date (Web): March 21, 2000. We are grateful to the National Science Foundation for financial support (CHE-9614968 to M.N. and GP-8540 to J.D.R.). | ||||||||||||
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Issue or Number: | 13 | ||||||||||||
DOI: | 10.1021/ja991114h | ||||||||||||
Record Number: | CaltechAUTHORS:20151001-101404659 | ||||||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20151001-101404659 | ||||||||||||
Official Citation: | Kinetics and Equilibrium Constants for Reactions of α-Phenyl-Substituted Cyclopropylcarbinyl Radicals Thomas A. Halgren, John D. Roberts, John H. Horner, Felix N. Martinez, Christopher Tronche, and Martin Newcomb Journal of the American Chemical Society 2000 122 (13), 2988-2994 DOI: 10.1021/ja991114h | ||||||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||
ID Code: | 60659 | ||||||||||||
Collection: | CaltechAUTHORS | ||||||||||||
Deposited By: | Ruth Sustaita | ||||||||||||
Deposited On: | 02 Oct 2015 16:07 | ||||||||||||
Last Modified: | 10 Nov 2021 22:37 |
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