All the possible decomposition pathways of gamma-butyrolactone were explore
d with UMP4/6-31G**//UHF/6-31G** methods. Two concerted pathways, one leadi
ng to decarbonylation and the other to decarboxylation, and one consecutive
pathway, which began with the cleavage between C5-O1 followed by cleavage
between C2-C3 leading to decarboxylation, were the three lowest pathways on
the potential energy surface. Of the three, the concerted decarbonylation
pathway was the easiest energetically. For the decarboxylation process, the
consecutive pathway was slightly preferred over the concerted, but both we
re possible since their energy barriers were higher than that of concerted
decarbonylation by about 13 kJ/mol only. (C) 1999 Elsevier Science B.V. AU
rights reserved.