How hydrogen-bonded MnO4- can influence oxidation of olefins in both gas phase and solution?



The reaction pathway (including the transition state) of ethylene addition to permanganate (MnO4-) in the presence of ethylene glycol (EG) has been qualitatively and quantitatively studied by means of B3LYP/6-311++G** theoretical analysis. Interestingly, by cluster formation of the EG with permanganate, oxidation reaction becomes thermodynamically and kinetically more favorable. The influences of electron-withdrawing as well as electron-donating substituents were also explored.

Results of the quantum theory of atoms in molecules and natural bond orbital analyses revealed that [3 + 2] addition reaction of alkenes in the presence of EG as hydrogen bonding donor to MnO4- becomes more exothermic. Natural resonance theory (NRT) is used to calculate natural bond order and bond polarity. The NRT result indicates that the polarity of Mn–O bond is affected by EG coordinated to MnO4-. Moreover, the conceptual DFT descriptors such as chemical potential (μ), hardness (η) and electrophilicity index (ω) show that hydrogen bonding to permanganate can affect the addition of MnO4- to double bond in a satisfactory way. We also carried out geometrical optimizations with the polarizable continuum model to account for the solvent effect, and the results were compared with those in the gas phase. Copyright © 2012 John Wiley & Sons, Ltd.