SN2 kinetics

Sn2 Nucleophilicity of (CH30)2P0. To determine the intrinsic SN2 kinetic nucleophilicity of (CH30)2P0, we investigated the reactions of the anion with the series of CH3X molecules listed in Table V. The rates of these reactions vary from modest with the most reactive CH3I molecules to slow with CH3Br to no observed reaction with CH3C1. From the results, we conclude that the phosphoryl anion is kinetically a poor nucleophile in SN2 displacement reactions. 

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