The Effect of Solvent on the Structure of the Transition State for the SN2 Reaction between Cyanide Ion and Ethyl Chloride in DMSO and THF Probed with Six Different Kinetic Isotope Effects
2006 (English)In: J. Org. Chem, no 71, 4742-4747 p.Article in journal (Refereed) Published
The secondary a- and B-deuterium, the a-carbon, the nucleophile carbon, the nucleophile nitrogen, and the chlorine leaving group kinetic isotope effects forthe SN2 reaction between cyanide ion an dethyl chloride were determined in the very slightly polar solvent THF at 30 C. A comparison of these KIEs with those reported earlier for the same reaction in the polar solvent DMSO shows that the transition state in THF is only sligthly tighter with very slightly shorter NC-Ca-CI bonds. This minor change in transition state structure does not account for the different transition structures that were earlier suggested by interpreting the experimental KIEs and the gas-phase calculations, respectively. It therefore seems unlikely that the different transition states suggested by the two methods are due to the lack of appropriate solvent modeling in the theoretical calculations. Previously it was predicted that the transition state of SN2 reactions where the nucleophile and the leaving group have the same charge would be unaffected by a charge in solvent. The experimental KIEs support this view.
Place, publisher, year, edition, pages
2006. no 71, 4742-4747 p.
IdentifiersURN: urn:nbn:se:uu:diva-82115DOI: 10.1021/jo052375eOAI: oai:DiVA.org:uu-82115DiVA: diva2:110030