DFT Study On The Mechanism Of Grignard Reagent Formation

Grignard reagent is one of the most fundamental and useful reagents in organic synthesis.The mechanism of Grignard reagent formation(GRF)was heavily discussed in the literature to account for its unique selectivity and kinetics.Yet,mechanisms hitherto cannot fully account for both of the important aspects of GRF.In the current work,the mechanism of GRF was studies using plane-wave based density functional theory(DFT)method periodic magnesium(0001)surface model was built to model the metallic magnesium surface.Dissociation of different organic halides on magnesium surface were studied.The surface anion intermediate and the orientation selectivity were proposed to account for the configuration retention of alkene and aromatic halides.In addition,we investigated the desorption and formation of Grignard reagent on the surface model.A cation desorption pathway was proposed.The cation intermediate was further validated with electrochemical experiments.The cation desorption mechanism predicts two different configuration retention mechanisms for cyclic alkyl halides,which is in accordance with experimental observations.Finally,the induction period of GRF and the elimination of induction period was explained with kinetic simulations based on the ionic model of GRF.