Ab Initio Investigations of Some 1, 2-Diols Rearrangement Via G3 Calculations

Conformational analysis of protonated of 1,2-ethanediol, 1,2-propanediol and 2-methyl- 1,2-propanediol had been studied and the resulting rotational transition states had been determined. The transition states that result from the proton transfer from 2°- and 3°-OH groups (M1) to 1o-OH group (M2) had been also determined. It had been found that the equilibrium favors M1 formation. This result is agreeable with the published data. The possible mechanisms for the rearrangement of M1 to the corresponding aldehyde had been discussed. The obtained G3 results had been compared with the published theoretical and experimental results. It had been found that G3 method excludes the two-steps mechanism in contrast to other calculations with lower level. The possibility of formation of epoxides as by-products had been also discussed.