Diphenyl phosphate, hydrolysis

Tests in pure water, river water, and activated sludge showed that commercial ttiaryl phosphates and alkyl diphenyl phosphates undergo reasonably facile degradation by hydrolysis and biodegradation (163—165). The phosphonates can undergo biodegradation of the carbon-to-phosphoms bond by certain microorganisms (166,167). 

One of the earliest reports on the use of dendrimers in catalysis is the unimolecu-lar decarboxylation of 6-nitro-benzisoxazole-3-carboxylate in the presence of a dendrimer comprising ether dendrons which are functionalized at their periphery with tetra-alkylammonium cations (e.g. 20, Scheme 21) [30]. In aqueous media, the quaternary ammonium groupings promote the reactivity of organic anions which presumably bind in high concentration to the polycationic periphery of the dendrimer. The latter species enhances the rate of the bimolecular hydrolysis of p-nitrophenyl diphenyl phosphate catalyzed by o-iodosobenzoate ion. 

A comparable metabolic fate is documented for the hydraulic fluid tributyl phosphate. Following administration to rats, the Bu groups were oxidized to alcoholic, ketonic, and acidic metabolites. The oxidized Bu groups were then cleaved by enzymatic hydrolysis [103], With 2-ethylhexyl diphenyl phosphate (9.48), an interesting case of regioselectivity was noted during its in vivo metabolism in rats. Indeed, this flame retardant and plasticizer was... 

The flame retardant mechanism of PC/ABS compositions using bisphenol A bis(diphenyl phosphate) (BDP) and zinc borate have been investigated (54). BDP affects the decomposition of PC/ABS and acts as a flame retardant in both the gas and the condensed phase. The pyrolysis was studied by thermogravimetry coupled with fourier transform infrared spectroscopy (FUR) and nuclear magnetic-resonance spectroscopy. Zinc borate effects an additional hydrolysis of the PC and contributes to a borate network on the residue. 

Scheme 1 Hydrolysis of diphenyl-carbonate (1) to give 4-nitro-phenol (2), 4-acetamido-phenol and carbon dioxide. The diphenyl-phosphate (4) was used as TSA to mimic the tetrahedral transition state formed during the hydrolysis...

Robinson, 1969a). It is probable that the hydrophobic nature of the phenyl groups of p-nitrophenyl diphenyl phosphate results in deep penetration of the neutral ester in the Stern layer, thus shielding the phosphoryl group from nucleophilic attack. Unlike other reactions between nucleophiles and neutral substrates catalyzed by cationic micelles (Bunton and Robinson, 1968, 1969a) and the hydrolysis of dinitrophenyl phosphate dianions in the presence of cationic micelles (Bunton et al., 1968), the catalysis of the hydrolysis of -nitrophenyl diphenyl phosphate by CTAB arises from an increase in the activation entropy rather than from a decrease in the enthalpy of activation. The Arrhenius parameters for the micelle-catalyzed and inhibited reactions are most probably manifestations of the extensive solubilization of this substrate. However, these parameters can be composites of those for the micellar and non-micellar reactions and the eifects of temperature on the micelles themselves are not known. Interpretation of the factors which affect these parameters must therefore be carried out with caution. In addition, the inhibition of the micelle-catalyzed reactions by added electrolytes has been observed (Bunton and Robinson, 1969a Bunton et al., 1969, 1970) and, as in the cases of other anion-molecule reactions and the heterolysis of dinitrophenyl phosphate dianions, can be reasonably attributed to the exclusion of the nucleophile by the anion of the added salt. 

Similar to catalytic antibodies, we observed some product inhibition. In the case mentioned, the reaction rate was calculated from the amount of released acid. If the calculation is based on phenol release, the rate enhancement turned out to be nearly doubled. Hydrolysis of carbonates should avoid this difficulty. Therefore, diphenyl phosphate was used as template, and the hydrolysis of diphenyl carbonate was then investigated [13]. Compared to solution an enhancement of 982-fold was obtained and typical Michaelis-Menten kinetics were observed (K ,ax = 0.023 mM/min, = 5.01 mM, = 0.0115/min, kaalK = 2.30/min/M). 

The 1-phosphates of a- and /3-lactose have been synthesized by interacting silver diphenyl phosphate with hepta-O-acetyl-a-lactosyl bromide, with the elimination of silver bromide, followed by hydrogenolysis of the phenyl groups and fractional recrystallization of the barium salts. /3-Lactosyl phosphate is more readily hydrolyzed than the a anomcr in N hydrochloric acid at 37° (64% and 26% hydrolysis, respectively, after 80 minutes). 

Diphenyl phosphate N,N -diethyl(4-vinylphenyl)amidine MMA EDMA MeCN, cyclohexanol+dodecanol or toluene Using transition state analog selective hydrolysis of diphenyl carbonate and diphenyl carbamate bulk and suspension polymerization [174)... 

Similarly, diphenyl phosphate as amidinium salt 18 acts as a stable transition-state analogue for carbonate 19 and carbamate hydrolysis [27] (for a detailed review, see [1]). 

Why is Ce(IV) so active for DNA hydrolysis What factors differentiate this metal ion from other lanthanide ions and non-lanthanide ions Do the f-oibitals of Ce(IV) take significant roles in the catalysis These questions are critically important for practical applications of this catalysis and also from the viewpoints of pure rare earth chemistry. In order to answer them, core-level photoelectron spectroscopy (Shigekawa et al., 1996), as well as EXAFS (extended X-ray absorption fine structure) and XANES (X-ray absorption near edge stracture) measurements (Shigekawa et al., 1999), were carried out. The spectroscopic analysis was simplified by using diphenyl phosphate (DPP) in place of DNA, and the EXAFS and the XANES measurements were carried out on the samples frozen in liquid nitrogen. 

The effectiveness of three isomers, 2-, 3- and 4-hydroxyiminomethyl-l-pyridinium iodide (61) as agents to catalyse the hydrolysis in cationic micellar media of p-nitrophenyl acetate (PNPA) and p-nitrophenyl diphenyl phosphate (PNPDPP) were studied at pH 8. The 2-isomer was found to be the most effective for the hydrolysis of the carboxylic ester PNPA, but the 4-isomer for the hydrolysis of the triphosphate ester PNPDPP. ... 

VassUev K, Ford WT (1999) Poly(propylene imine) dendrimer complexes of Cu(II), Zn(II), and Co(III) as catalysts of hydrolysis of p-nitrophenyl diphenyl phosphate. J Polym Sci A Polym Chem 37 2727... 

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