799-87-1Relevant academic research and scientific papers
Design of experiments on the transesterification of tris(p-nitrophenyl) phosphate with sodium methoxide
Seiceira, Rafael C.,Nakayama, Hatumi T.,Costa Neto, Claudio,Cajaiba Da Silva, Joao F.,Pedrosa, Marcelo S.
, p. 389 - 395 (2007/10/03)
A design of experiments was conducted to study the transesterification of tris(p-nitrophenyl) phosphate with sodium methoxide. The factorial design was performed to check the experimental conditions that favored ths yield of bis(p-nitrophenyl) methyl phosphate in a semi-batch process. The experiments were performed using a Mettler RC1 calorimeter. The reaction temperature, the addition order of reagents and the time spent in those additions were analyzed at two different levels. The results showed the addition order of reagents as the most important factor to guarantee the improvement of the reaction yielding bis(p-nitrophenyl) methyl phosphate. It was demonstrated that the temperature has a small effect on the reaction yield between 5 and 30°C. An important effect was observed with regard to the addition time of reagents and yield: when the tris(p-nitrophenyl)phosphate is added to the methoxide solution (58% on average) while no effect was observed when the methoxide solution was added to the phosphate (87% on average). Theses results indicated that the addition could be made in times shorter than five minutes under the latter condition. Copyright Taylor & Francis Inc.
Electronic Structure and 31P NMR Chemical Shift of Substituted Triaryl, Diaryl Methyl and Dimethyl Aryl Phosphates - a Semi-empirical Molecular Orbital Approach
Silva, J. F. Cajaiba da,Pedrosa, M. S.,Nakayama, H. T.,Neto, C. Costa
, p. 97 - 106 (2007/10/03)
The 31P NMR chemical shift of triaryl phosphate, diaryl methyl phosphate and dimethyl aryl phosphate series was determined.The δ31P values exhibit an increasing downfield trend when aryl substituents are exchanged for alkyl groups and δ31P values show an increasing upfield trend as the electron withdrawing ability of the substituent in the aromatic ring is increased.Semi-empirical calculations showed an increasing positive charge on phosphorus atom and an increasing phosphoryl bond order when δ31P values go upfield.These results are in good agreement with the effect of "back bonding" from the phosphoryl oxygen to the phosphorus atom. - Keywords: 31P NMR chemical shifts; structural effects; molecular orbitals; triaryl phosphates; diaryl alkyl phosphates; dialkyl aryl phosphates
Solvent isotope effects as a probe of general catalysis and solvation in phosphoryl transfer
Bryan,Schowen,Schowen
, p. 931 - 938 (2007/10/03)
Phosphoryl transfer to methanol from PNNN, PMNN, and PMMN exhibits general base catalysis by acetate ion but no detectable catalysis by acetic acid. For PNNN, acetate catalysis produces normal solvent isotope effects that arise from a one-proton catalytic bridge in the transition state. The proton inventory for the least reactive substrate PMMN is suggestive of transition-state stabilization, while the proton inventory for the most reactive substrate PNNN suggests only generalized transition-state solvation. Furthermore, the proton inventory for PMNN suggests an intermediate situation. The data are consistent with a model in which transition states with exterior concentrations of charge favor stabilization of the charge by isotope-fractionating one-proton bridges, while transition states with distributed charge favor stabilization of the charge by many distributed sites.
Organo phosphorus compounds and pesticidal compositions
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, (2008/06/13)
The invention relates to a new family of organophosphorus compounds. The compounds have a biological activity and can be used as insecticides. The compounds belong to the group of bis-aminophenyl phosphoric acid esters.
