Acetic anhydride reacts with nitro or methyl m-phenolates through either a one-step or two-step nucleophilic acyl substitution reaction. One of the main goals of this investigation is to computationally model the kinetics of this reaction in both gas and SMD aqueous phase and study the transition state energies as well as charge distribution changes as the reaction progresses, in order to determine the most likely reaction mechanism. The project uses the M06-2X density functional method and the 6-31+G** basis set, which, according to previous work on this topic, will most accurately describe these reactions. The Merz-Kollman model and the CHelpG model were electrostatic mapping models used to study charge distribution across the different states of the reaction. Results obtained from several conformers so far, including those produced in previous summers, indicates that the general reaction profiles vary significantly between conformers across both types of phenolates, and that both step-wise and concerted mechanisms have been observed within each phenolate group. However, a general trend is seen where the m-nitro reaction is concerted whereas the m-methyl reaction is step-wise. By comparing these results with those produced using the MP2 method, we hope to shed more light on the mechanistic properties of these NAS reactions.

Investigations into the mechanism of the nucleophilic substitution reaction using M06-2X

251st National Meeting (2016)

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