Structures, rotational barriers, thermochemical properties, and additivity groups for 2-propanol, 2-chloro-2-propanol and the corresponding alkoxy and hydroxyalkyl radicals

Document Type

Article

Publication Date

4-18-2002

Abstract

Structures, internal rotational barriers, and thermochemical properties of 2-propanol, 2-chloro-2-propanol, isopropoxy radical, 1-chloro-1-methylethoxy, 2-hydroxypropyl, and 2-chloro-2-hydroxypropyl were computed by ab initio and density functional calculations. Molecular structures and vibration frequencies were determined at the B3LYP/6-31G(d,p) density functional level, with single-point calculations for the energy at the B3LYP/6-311+G(3df,2p) and CBSQ//B3LYP/6-31G(d,p) levels. The S298o and Cp(T)'s (0 ≤ T ≤ 5000 K) from vibrational, translational, and external rotational contributions were calculated using statistical mechanics based on the vibrational frequencies and structures obtained from the density functional study. Potential barriers for the internal rotations were calculated at the B3LYP/6-31G(d,p) level, and hindered rotational contributions to S298o and Cp(T)'s were calculated by using direct integration over energy levels of the internal rotational potentials. The ΔHf,298o values for the above species were calculated using several isodesmic reactions for each species, and bond energies were also determined. The C/C2/Cl/O group value was derived for use in Benson-type group additivity. Hydrogen bond increment groups for C2CȮ, C2CClȮ, ĊC(C)OH, and ĊC-(C)CIOH were also developed. The recommended ΔHf,298o values for (CH3)2CHOH, (CH3)2CHȮ, ĊH2-(CH3)CHOH, (CH3)2CClOH, (CH3)2CClȮ, and ĊH2CCl(OH)CH3 are -69.19 ± 2.2, -11.85 ± 1.9, -14.95 ± 2.8, -79.83 ± 2.1, -25.88 ± 2.0, and -29.00 ± 2.8 kcal/mol, respectively. The radical (CH3)2CClȮ has low stability with a short atmospheric lifetime. Bond energies for the methyl hydrogens and the hydroxyl hydrogen are 102 and 105 kcal/mol in 2-propanol and 103 and 106 kcal/mol in 2-chloro-2-propanol. The recommended HBI values for oxy(chloro)alkanes are presented for use in group additivity.

Identifier

0037129489 (Scopus)

Publication Title

Journal of Physical Chemistry A

External Full Text Location

https://doi.org/10.1021/jp014442o

ISSN

10895639

First Page

3947

Last Page

3956

Issue

15

Volume

106

This document is currently not available here.

Share

COinS