Solvation free energy and Modeling chemical reactions - Cobalt

More documents

Recommendations

Info

Potential of mean force: An application• The application of slow-growth IRC methods to the SN 2 reaction of methylchloride with the chloride anion, as investigated by Artur Michalak of the Zieglergroup, will be discussed.• Of particular interest (in addition to the quality of the predicted energies) is theevident rotational freedom of the reactants relative to one another at coordinatesquite close to the transition state – a phenomenon not observed in enthalpic IRCcalculations.Empirical Approaches• Force field methods have been developed to treat reactions.• As an example: The reaction of enol boronates with aldehydes, shown below,was investigated:OBL 2OH R 2OOHR 1R 1 R 2Each conformer of the starting material can go through one of two transitionstates – the “chair” conformation, or the “boat” conformation. These transitionstates are shown below for the trans starting material:OR1BOR 2OOO OBR 2 BR 2R 1 R 1
R 2OOOB OB OB ODepending on the relative orientations of the two reactant molecules (R 2 axial orequatorial), each transition state can, in turn, give one of two productconformations. Both reactions shown above lead to the product given below:OOHR 1 R 2In this study, empirical parameters were fit to match experimentally-determinedtransition state structures where R 1 = R 2 = H. These parameters were then usedsuccessfully to predict product ratios for other substituents, whose interactionsthrough the reaction were primarily steric.
Page 1 and 2: [Note that some of what follows is
Page 5: 1. We begin by choosing a model, an

Solvation free energy and Modeling chemical reactions - Cobalt

Create successful ePaper yourself

Delete template?

Save as template?