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COMPARATIVE STUDIES OF THE EFFECT OF POLYCYCLIC AROMATIC HYDROCARBON GEOMETRY ON THE HYDROLYSIS OF DIOL EPOXIDES
Citation:
Brown, K. W., S. B. Little, AND J. R. Rabinowitz. COMPARATIVE STUDIES OF THE EFFECT OF POLYCYCLIC AROMATIC HYDROCARBON GEOMETRY ON THE HYDROLYSIS OF DIOL EPOXIDES. Presented at International Symposium on Polycyclic Aromatic Compounds, Univ. of Cincinnati, Cincinnati, Ohio, Sept. 9-13/2001.
Description:
Comparative studies of the effect of polycyclic aromatic hydrocarbon geometry on the hydrolysis of diol epoxides
The interaction of the diol epoxides (DEs) of both planar and non-planar PAHs with water have been examined using quantum mechanical and molecular dynamics. The potential protonation of the epoxide ring, with subsequent ring opening and carbocation formation, was modeled. To determine probable water locations around the DE, molecular dynamics simulations using the OPLS force field were carried out on the diol epoxide surrounded by a 22A box of explicit water molecules. Results for 30ps simulations of BaP-DE indicate that 12-20% of the time, depending on the conformation of the DE, there is a water within a good hydrogen-bonding distance and orientation of the epoxide oxygen. Examination of the snapshots during the simulations showed that the bound waters existed in several preferred configurations which are also dependent upon the PAH-DE geometry. The most common geometries of the DE and bound waters were then used as starting points in ab initio quantum mechanical studies where the O-H bond in the water was lengthened, bringing the hydrogen closer to the epoxide oxygen. The potential energy surfaces of these processes and the energetics of the transfer of the hydrogen from the water to the epoxide oxygen are examined.
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