Premium
Theoretical studies on the gas‐phase pyrolysis of acetic anhydride and diacetyl sulphide
Author(s) -
Lee Ikchoon,
Cha Ok Ja,
Lee BonSu
Publication year - 1990
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610030502
Subject(s) - chemistry , diacetyl , ketene , reactivity (psychology) , mndo , thermal decomposition , enthalpy , acetic anhydride , bond cleavage , nucleophile , acetic acid , pyrolysis , transition state , organic chemistry , decomposition , medicinal chemistry , molecule , catalysis , thermodynamics , medicine , physics , alternative medicine , pathology
The gas‐phase thermal decomposition of diacetyl compounds, (CH 3 CO) 2 X with X = O and S, was investigated theoretically using the semiempirical MO methods MNDO and AM1. The initial decomposition of the diacetyl compounds proceeded through a six‐membered ring transition state involving the keto form with a slightly lower activation enthalpy for diacetyl sulphide (X = S); the process via an enolic form of the transition state was kinetically unfavourable. In the initial decomposition of the diacetyl compounds and in the subsequent pyrolysis of acetic and thioacetic acid, ketene formation was found to be the most preferred path, where the ease of C α X bond cleavage is relatively more important than nucleophilic attack on the β‐hydrogen in determining the overall reactivity. In the methane formation process, the reactivity was entirely dependent on the XH bond strength in CH 3 COXH where X = S, NH and O.