Chemical reactions inside structured nano-environment: S(N)2 vs. E2 reactions for the F(-) + CH(3)CH(2)Cl system.

A new receptor for S(N)2 transition states, named NPTROL, is proposed. This molecule has a cavity and four hydroxyl groups that are able to interact with ionic S(N)2 and E2 transition states. Its catalytic effect and selectivity was investigated through high level ab initio calculations using the fluoride ion plus ethyl chloride in DMSO solution as a model system. Calculations at the ONIOM[CCSD(T)/6-311+G(2df,2p) : MP2/BASIS1] level of theory and solvent effects, included through a continuum solvation model, indicate that NPTROL is able to catalyze the S(N)2 pathway and has an inverse effect on the E2 pathway. Inside the NPTROL cavity, the ΔG(‡) for the S(N)2 transition state is 5.00 kcal mol(-1) lower than that for E2, and as a consequence this reaction becomes highly selective toward the S(N)2 product.