Comparison of AM1 and PM3 in MOPAC6 with literature for the thermodynamic parameters of C1 and C2 chlorocarbons

Document Type

Article

Publication Date

1-1-1998

Abstract

Ideal gas thermodynamic properties, ΔHf°298, S°298, and .Cp(T) (300 ≤ T/K ≤ 1500), for all C1 and C2 and eight C3-C6 chlorinated hydrocarbons are calculated by AM1 and PM3 in MOPAC6 and then compared with the available literature data. The approximation method of Pitzer and Gwinn is used to account for internal rotor contributions to S°298 and Cp(T) (300 ≤ T/K ≤ 1500), in place of the torsion frequency estimation in MOPAC. AM1- and PM3-derived S°298 and Cp(T) (300 ≤ T/K ≤ 1500) are found to be consistent with the literature data (relative deviation ≤ ±5%) except S°298 of C2HCl5 and Cp(300-500 K) of chloroacetylenes. ΔHf°298 of CCl4, C2HCl3, C2Cl4, and C2Cl2 obtained by AM1 and Δf°298 of CH2Cl2, CH2ClCH2Cl, CH2ClCHCl2, CHCl2CHCl2, C2Cl4, and C2Cl2 obtained by PM3 are not in good agreement with the literature values (deviation ≥ ±5 kcal/mol). ΔHf°298 (kcal/mol) calculated by PM3 are corrected as follows: ΔHf°298,eXperiment = -2.35 + 1.086ΔDf°298,pM3 for the partially chlorinated hydrocarbons; AHf°298,experiment = 5.36 + 1.066ΔHf°298,pM3 for the fully chlorinated hydrocarbons. A modified group additivity method implemented in THERM is shown to be precise for predicting ΔHf°298, S°298, and Cp(T) (300 ≤ T/K.≤ 1500) of C1 and C2 chlorocarbons. AM1- and PM3-calculated ΔHf°298 for chlorocarbons can be improved by linear correction equations. Comparison of estimations from group additivity, corrected MOPAC6/PM3, and literature data suggests that the modified group additivity is the better estimation method. © 1998 American Chemical Society.

Identifier

0032137578 (Scopus)

Publication Title

Industrial and Engineering Chemistry Research

External Full Text Location

https://doi.org/10.1021/ie980126t

ISSN

08885885

First Page

3497

Last Page

3507

Issue

8

Volume

37

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