Equilibrium CH-acidity of carbamoylmethylphosphoryl compounds in dimethyl sulfoxide

Abstract

1. The equilibrium CH-acidity of carbamoylmethylphosphoryl compounds (CMP) relative to 9-phenylfluorene was determined by the indicator method in DMSO (K+ counterion). 2 A linear correlation has been established between the pK values of CMP with theσCH2 constants of the substituents at the central C atom. TheσCH2 constants were calculated for the (t-Bu)2P(O), (cyclo-Hex)2P(O), Ph(EtO)P(O) and C(O)NEt2 groups. 3. Analysis of the dependences of the pK of CMP and other previously studied phosphoryl-substituted CH-acids on ∑σP of the substituents at the P atom shows that for all compounds, except for those containing an Ar2P(O) group, there is a single linear dependence. Compounds with two aryl groups at the P atom show a different dependence.