The SN 2 reactions having a symmetrical transition state were studied in a dipolar aprotic solvent. A good Hammett correlation was found for the chlorine isotopic exchange reactions in acetonitrile between tetraethylammonium chloride and three types of substituted methyl chlorides, 2-arylethyl chlorides, chloromethyl aryl ethers, and chloromethyl aryl sulfides. The reaction constant was positive for 2-arylethyl chlorides and negative for the methyl ...
