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Hydrogen abstraction by chlorine atom from small organic molecules containing amino acid functionalities: an assessment of theoretical procedures

Date

2009

Authors

Taylor, Mark S.
Ivanic, Sandra A.
Wood, Geoffrey P. F.
Easton, Christopher
Bacskay, George B.
Radom, Leo

Journal Title

Journal ISSN

Volume Title

Publisher

American Chemical Society

Abstract

A high-level quantum chemistry investigation has been carried out for the abstraction by chlorine atom of hydrogen from methane and five monosubstituted methanes, chosen to reflect the chemical functionalities contained in amino acids and peptides. A modified Wl' procedure is used to calculate benchmark barriers and reaction energies for the six reactions. The reactions demonstrate a broad range of barrier heights and reaction energies, which can be rationalized using curve-crossing and molecular orbital theory models. In addition, the performance of a range of computationally less demanding electronic structure methods is assessed for calculating the energy profiles for the six reactions. It is found that the G3X(MP2)-RAD procedure compares best with the Wl' benchmark, demonstrating a mean absolute deviation (MAD) from Wl' of 2.1 kJ mol-1. The more economical RMP2/G3XLarge and UB2-PLYP/G3XLarge methods are also shown to perform well, with MADs from Wl' of 2.9 and 3.0 kJ mol-1, respectively.

Description

Keywords

Keywords: Barrier heights; Chemical functionality; Chlorine atom; Energy profile; Hydrogen abstraction; Mean absolute deviations; Molecular orbital theory; Reaction energy; Small organic molecules; Abstracting; Amination; Amino acids; Atoms; Chlorine; Electronic st

Citation

Source

Journal of Physical Chemistry A

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1021/jp9029437

Restricted until

2037-12-31