Displacement at phosphorus by a mechanism with A1 character. Acid-catalyzed hydrolysis of phosphinanilides

Abstract

Studies of the acid-catalyzed hydrolysis of phosphinanilides demonstrate that protonation has a profound labilizing effect on P-N bonds. In H2S04: -V-(p-nitrophenyl)diphenylphosphinamide exhibits a kinetic dependence on A0 with rate law, v = k[amide]/io° 9, and nonlinear dependence of log k on log [acid]. Examination of the dependence of the rate constants on acidity functions indicates an Ai mechanism: application of the Zucker-Hammett or Bunnett methods requires an acidity function which correctly describes the protonation behavior of the substrate-when log k is plotted vs. Ha, the acidity function for amides, a straight line with slope 1.0 results. This analysis of the dependence of rate on acidity and the large solvent isotope effect, kfk-= 2.8, provides strong evidence for an Ai mechanism. The variation in rate with TV-aryl substituents, p = -1.7, is consistent with a tran-Amer. Chem. Soc., 94,9260 (1972).

Nucleophilic Reactivity of N-Phosphorylated Ethyleneimine†

“…It is interesting to note that in the conjugate acid of 5b, it is the aziridine carbon, not the phosphorus atom, that represents the electrophilic reaction centre, and that the reaction leads to a phosphoramidate product, not to PsN bond cleavage, as is usually observed for a phosphoric amide system under acidic conditions. 7 As expected, all ions 5 were found to be perfectly stable when incubated in the D 2 O-[ 2 H 5 ]pyridine (4 :1, v/v) at 40 °C for 48 h. Since in that medium the N-protonation of 5 should be negligible, no reaction takes place, notwithstanding the presence of highly nucleophilic species.…”

New Heterocyclic Mono‐ and Bis(α‐hydroxymethyl)phosphinic Acids: Synthesis and CuIIBinding Abilities

“…The low value for the energy of activation (Ea) is significant and indicates the ease of splitting a C-P bond in 2a. The calculated entropy of the reaction (∆S ϶ ) is -95.67 J mol -1 K -1 , and the value may reflect unease in the protonation of oxygen [23] in a phosphinic group of 2a before splitting. It is noteworthy that the rate constants were calculated from estimated 31 P NMR spectroscopic integrated signals, and therefore, these results should not be considered as exact data for mere kinetic studies.…”

New synthesis of S(Se)-alkyl phosphorothio(seleno)lates from the corresponding phosphoroanilidates. Stereospecific cleavage of the phosphorus-nitrogen bond in chiral phosphoroanilidates

“…(/? )-(-)-3 was obtained from chlorinolysis of (S)-(-)-0-ethyl-S-methyl ethylphosphonothiolate (4) with sulfuryl chloride and was not isolated in a pure form prior to aminolysis. Reaction of the sodium salt of (-)-l with carbon disulfide followed by alkylation of the resulting 0ethyl ethylphosphonothioate anion with methyl iodide gave 4 with the same configuration as the starting thiolo ester used for chlorinolysis, although its specific rotation value was much lower.…”

“…)-(-)-3 was obtained from chlorinolysis of (S)-(-)-0-ethyl-S-methyl ethylphosphonothiolate (4) with sulfuryl chloride and was not isolated in a pure form prior to aminolysis. Reaction of the sodium salt of (-)-l with carbon disulfide followed by alkylation of the resulting 0ethyl ethylphosphonothioate anion with methyl iodide gave 4 with the same configuration as the starting thiolo ester used for chlorinolysis, although its specific rotation value was much lower. The transformations described above constitute, according to Cram's classification,15 a podal, triligostatic, three-reaction cycle in which both chlorinolysis of phosphoryl thiolo esters16 as well as aminolysis of phosphoryl chloroanhydrides17 are known to proceed with inversion of configuration at phosphorus.…”