Solution-phase energy profiles for trigonal bipyramidal species postulatedas intermediates for the hydrolysis of methyl ethylene phosphate

We present results of solution-phase ab initio and DFT investigations on th e trigonal bipyramidal (TBP) intermediates postulated for the hydrolysis of methyl ethylene phosphate (MEP). A key intermediate for the hydrolysis wou ld not be a TBP species with the hydroxyl group axial, but would be a TBP i ntermediate with the hydroxyl group equatorial. Considering the reaction pa thways through this intermediate, not only exclusive ring opening in the di lute alkaline hydrolysis of MEP but also significant amount of exocyclic cl eavage in the strong alkali can be rationalized. This interpretation is in accord with the mechanisms proposed by Lim et al. and by Lonnberg et al. (C ) 1999 Elsevier Science B.V. All rights reserved.