  In this paper, carried out were the investigations on the synthetic reaction
mechanisms of 3,4-epoxybutyric acid (EBA) from 3-hydroxy-{\gamma}-butyrolactone
(HBL) with two different activating agents, methanesulfonyl chloride (MC) or
acetic acid (AA), respectively, and on the convertion of EBA to L-carnitine by
density functional theory (DFT/B3LYP). The theoretical calculations showed that
the two reaction mechanisms of EBA synthesis with MC or AA as an activating
agent were nearly the same. If activated HBL is hydrolysed, not only ring
cleavage reaction, but also reverse reaction to HBL can take place. In the case
of AA as the activating agent, the activation energy ( energy barrier ) for EBA
synthesis is 1.8 times larger than that with MC. It means that the synthesis of
EBA with AA may make more by-products with less yield of EBA than that with MC,
that can be one reason why AA gave the less yield than MC in EBA synthesis, as
reported in the previous experimental study.
