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A quantum chemical investigation of pyrolysis reactions of glyoxylic acid ethylester
Author(s) -
Bøhm Stanislav,
Skancke P. N.
Publication year - 1991
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560400405
Subject(s) - chemistry , formic acid , ring (chemistry) , glyoxylic acid , transition state , ab initio , computational chemistry , reactivity (psychology) , photochemistry , organic chemistry , catalysis , medicine , alternative medicine , pathology
Two possible reaction paths for the pyrolysis of the ethylester of glyoxylic acid have been studied by ab initio molecular orbital calculations. The basis sets 3‐21 G and 6‐31 G * have been used, and electron correlation has been included by Møller–Plesset calculations up to fourth order. Our calculations indicate that the reaction leading to acid and ethylene through a 6‐membered ring transition state is favored relative to a process involving a formyl hydrogen transfer via a 5‐membered ring to the alkyl unit leading to ethane, CO, and CO 2 . The predicted activation energies for these two reactions obtained at the highest level of calculation, MP 4( SDTQ )/6–31 G *, are 50.4 and 71.7 kcal/mol, respectively. The transition states have RHF wave functions that are stable relative to UHF solutions using the 3–21 G basis. The geometry of the transition states and IRC following indicate that both reactions are strongly asynchronous: The CO bond rupture is virtually completed before hydrogen transfer occurs. For comparative purposes, analogous calculations have been performed for the ethylester of formic acid, where it is confirmed that a 6‐membered ring transition state is preferred relative to a 4‐membered one by around 42 kcal/mol at the highest level of calculation.