Calculations Predict a Large Inverse H/D Kinetic Isotope Effect on the Rate of Tunneling in the Ring Opening of Cyclopropylcarbinyl Radical

Description:

Article on calculations predicting a large inverse H/D kinetic isotope effect on the rate of tunneling in the ring opening of cyclopropylcarbinyl radical.

Creator(s):
Creation Date: October 15, 2009
Partner(s):
UNT College of Arts and Sciences
Collection(s):
UNT Scholarly Works
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Total Uses: 195
Past 30 days: 2
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Creator (Author):
Zhang, Xue

University of North Texas

Creator (Author):
Datta, Ayan

University of North Texas

Creator (Author):
Hrovat, David A.

University of North Texas

Creator (Author):
Borden, Weston T., 1943-

University of North Texas

Publisher Info:
Publisher Name: American Chemical Society
Place of Publication: [Washington, DC]
Date(s):
  • Creation: October 15, 2009
Description:

Article on calculations predicting a large inverse H/D kinetic isotope effect on the rate of tunneling in the ring opening of cyclopropylcarbinyl radical.

Degree:
Department: Chemistry
Note:

Abstract: Tunneling rates are expected to decrease exponentially with the square root of the effective tunneling mass. Therefore, on substitution of a heavier for a lighter isotope, the observation of a large kinetic isotope effect (KIE), involving a substantial decrease in rate constant, is a commonly used diagnostic for a large contribution from quantum mechanical tunneling to a reaction. However, in this communication, the authors report the results of calculations that make the opposite prediction about some of the KIEs on the ring opening of cyclopropylcarbinyl radical (1) to 3-butene-1-y1 radical (2) by tunneling at cryogenic temperatures. Substitution of a heavier for a lighter isotope at the radical center (C1) of 1 is calculated to accelerate the rate of tunneling, giving KIEs at this carbon that are inverse. Of particular note is the authors' prediction that substitution of deuterium for both hydrogens at C1 will lead to a nearly 3-fold increase in the rate of reaction at temperatures so low that ring opening proceeds exclusively by tunneling from the lowest vibrational level.

Note:

Reprinted with permission from the Journal of the American Chemical Society. Copyright 2009 American Chemical Society.

Physical Description:

2 p.

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Subject(s):
Keyword(s): kinetic isotope effects | cyclopropylcarbinyl radicals
Source: Journal of the American Chemical Society, 2009, Washington DC: American Chemical Society, pp. 16002-16003
Partner:
UNT College of Arts and Sciences
Collection:
UNT Scholarly Works
Identifier:
  • DOI: 10.1021/ja907406q |
  • ARK: ark:/67531/metadc71808
Resource Type: Article
Format: Text
Rights:
Access: Public
Citation:
Publication Title: Journal of the American Chemical Society
Volume: 131
Page Start: 16002
Page End: 16003
Peer Reviewed: Yes