Synthesis and spectroscopic investigation of 4-methylphenyl esters of dimethyl phosphoramidochloridic acid and dimethyl phosphoramidofluoridic acid

Synthesis of 4-methylphenyl esters of N,N-dimethyl phosphoramidochloridic acid (1) and N,N-dimethyl phosphoramidofluoridic acid (2) is reported. 18-Crown-6 with potassium fluoride was found an effective reagent for the conversion of 1 to 2. These compounds were characterized by using H-1, P-31 NMR, infrared and mass spectroscopic data. Analysis of the H-1 NMR spectrum of ester 1 gives a long-range P-31-H-1 spin spin coupling ((7)J(P-H) = 1.2 Hz). A possible explanation for this unusual seven-bond coupling is discussed. In this study, a reasonable correlation between P-31 chemical shifts and P=O vibration frequencies is suggested.