Phosphoric acid derivatives, hydrolysis

Esters of phosphorous acid derived from aUphatic alcohols and unhindered phenols, eg, tris(nonylphenyl)phosphate (24), hydrolyze readily and special care must be taken to minimize decomposition by exposure to water or high humidity. The phosphorous acid formed by hydrolysis is corrosive to processing equipment, particularly at high temperatures. 

Monoester salts of phosphoric acid derived from fatty alcohol ethylene oxide adduct or alkylphenol ethylene oxide adduct useful as surfactants are prepared by addition of R(OCH2CH2) OH, alkali fluoride and (C12P0)20 in a molar ratio of 0.9-1.5 0.05-1 1.0 at -50 to + 10°C and hydrolysis of the Cl-containing intermediates with a base. The monoester phosphates showed comparable or better washing and foaming efficiency than commercial products [12]. 

B. Solvolysis of Phosphoric Acid Derivatives.—Interest continues in neighbouring-group participation in the solvolysis of phosphate esters. As a potential model compound for investigating the mechanism of ribo-nuclease action, the phenyl hydrogen phosphate ester of c/j-3,4-tetrahydro-furandiol (24) has been the subject of a detailed study. Above (and probably also below) pH 4 hydrolysis gives solely the cyclic phosphate (25)... 

J. P. Guthrie, Hydration and Dehydration of Phosphoric Acid Derivatives Free Energies of Formation of the Pentacoordinate Intermediates for Phosphate Ester Hydrolysis and of Monomeric Metaphosphate, J. Am. Chem. Soc. 1977, 99, 3391. 

Poly(methyl 3-(l-oxypyridinyl)siloxane) was synthesized and shown to have catalytic activity in transacylation reactions of carboxylic and phosphoric acid derivatives. 3-(Methyldichlorosilyl)pyridine (1) was made by metallation of 3-bromopyridine with n-BuLi followed by reaction with excess MeSiCl3. 1 was hydrolyzed in aqueous ammonia to give hydroxyl terminated poly(methyl 3-pyridinylsiloxane) (2) which was end-blocked to polymer 3 with (Me3Si)2NH and Me3SiCl. Polymer 3 was N-oxidized with m-ClC6H4C03H to give 4. Species 1-4 were characterized by IR and H NMR spectra. MS of 1 and thermal analysis (DSC and TGA) of 2-4 are discussed. 3-(Trimethylsilyl)-pyridine 1-oxide (6), l,3-dimethyl-l,3-bis-3-(l-oxypyridinyl) disiloxane (7) and 4 were effective catalysts for conversion of benzoyl chloride to benzoic anhydride in CH2Cl2/aqueous NaHCC>3 suspensions and for hydrolysis of diphenyl phosphorochloridate in aqueous NaHCC>3. The latter had a ti/2 of less than 10 min at 23°C. 

The above results lead to the conclusion that hydrolysis of carboxylic and phosphoric acid derivatives by ChE s proceeds in the same fashion. Therefore, we can now subdivide ester fission into two steps ... 

Solvolyses of Phosphoric Acid Derivatives.—The solvolysis of organic phosphates has been reviewed. A significant 0 isotope effect was observed in the solvolysis of the dianion of 2,4-dinitrophenyl phosphate, and since no such isotope effect is observed in the alkaline solvolysis of the dibenzyl ester this has been adduced as evidence for a monomeric metaphosphate elimination in the former case. The nucleophilic attack of hydroxide ion on bis-(2,4-dinitrophenyl) phosphate is inhibited by micelles of non-anionic detergents and this is attributed to binding of the substrate. Hydrolysis of 3,4-dimethoxyphenyl phosphate proceeds by way of the monoanion, the neutral molecule, and the conjugate acid, and is thus in accord with earlier results on other methoxyphenyl phosphates. ... 

The nucleic acids obtained from nucleoproteins are of unknown constitution, but their dissociation-products are fairly well known. They yield on hydrolysis phosphoric acid, pentoses, and derivatives of pyrimidine and of purine (415). It is beyond the scope of this book to discuss adequately the structure of the derivatives of pyrimidine and purine which are obtained from the nucleic acids. The graphic formulas of the derivatives which have been isolated are given here for reference. Uracil, cytosine, and thymine are derivatives of pyrimidine —... 

Fig.l. Catalytic antibodies. Examples of phosphonic- and phosphoric acid derivatives that have been used to generate catalytic antibodies for the hydrolysis of the specific ester and carbonate substrates shown. 1 2-4 refer to the steps in the hydrolysis of esters shown in Fig. 2 each step is effectively a group of electron shifts. 

Additives contribute to the stability of polymers but, under certain circumstances, some of them do not behave in a neutral manner. They can have indirect effects (via interaction with other components of the sophisticated formulations) or direct detrimental ones (by a radical attack of the polymer) on PP stability. For example, humid ingredients cause hydrolysis of aliphatic phosphites and lead consequently to phosphorus acid and other phosphoric acid derivatives [35]. 

In the presence of water, phosphites can hydrolyze and form phosphoric acid derivatives and alcohols [97]. The hydrolysis rate depends on the structure and physical form of the phosphite [101]. Its stability increases when R is changed from aliphatic to aromatic to sterically hindered aromatic. The effect of the hydrolysis on the effectivity as a stabilizer is limited, but decomposition products can have an influence... 

Nonspecific Phosphoesteroses. These enzymes cleave a variety of phosphoric acid derivatives, even synthetic substrates and lecithins (diesters of phosphoric acid with glycerol and choline). Such enzymes occur among other places in snake venom, and in the intestinal mucosa. Snake venom phosphatases specifically split 3 -phos-phate bonds, giving rise to 5 -monophosphates, whereas chemical hydrolysis yields a mixture of the 2 - and 3 -monophosphates. Free 3 -phosphate groups (the monoesters) are inhibitory in the enzymic reaction. 

Whereas nonionic ethylene oxide adducts discolor badly on contact with sodium hydroxide, phosphate derivatives of these nonionics exhibit good color stability even under these conditions. But in the presence of strong acids poly-oxyethylated phosphate esters undergo hydrolysis to the base nonionic and phosphoric acid. However, the free surface-active acids by themselves show little tendency to hydrolyze. They have a pH value of 2 in aqueous solution. 

An alternative sequence utilized 2-oxazolidone, which was readily synthesized from urea and ethanolamine, as the glycine equivalent. Subsequent treatment with phosphorous acid and formaldehyde produced iV-phosphonomethyl-2-oxazolidone 12 (16). Upon hydrolysis, and loss of CO2,12 provided the related derivative, iV-phosphonomethylethanolamine 13, which was oxidized at high temperature with a variety of metal catalysts including cadmium oxide (16) or Raney copper (17) to give GLYH3, after acidification. A similar oxidation route has also been reported starting from iV-phosphonomethy 1-morpholine (18). 

A variety of phosphoric acid triesters and their derivatives are used as pesticides. Although there are no natural phosphorotriesters, those artificial ones undergo decomposition in the soil, implying that some microorganisms exist which are capable of hydrolysing them. The first report on a stereoselective enzymatic phos-photriester hydrolysis was pubhshed in 1973, when Dudman and Zerner succeeded... 

Hydrolysis of diphenyl phosphorochloridate (DPPC) in 2.0 M aqueous sodium carbonate is also believed to be a two-phase process. DPPC is quite insoluble in water and forms an insoluble second phase at the concentration employed (i.e. 0.10 M). It seems highly significant that the hydrophobic silicon-substituted pyridine 1-oxides (4,6,7) are much more effective catalysts than hydrophilic 8 and 9. In fact, 4 is clearly the most effective catalyst we have examined for this reaction (ti/2 < 10 min). Since derivatives of phosphoric acids are known to undergo substitution reactions via nucleophilic addition-elimination sequences 1201 (Equation 5), we believe that the initial step in hydrolysis of DPPC occurs in the organic phase. Moreover, the... 

The monomeric metaphosphate ion itself commands a fair amount of attention in discussions of metaphosphates. It is postulated as an intermediate of numerous hydrolysis reactions of phosphoric esters 52 S4,S5) and also of phosphorylation reactions S6> kinetic and mechanistic studies demonstrate the plausibility of such an assumption. In addition, the transient formation of ester derivatives of meta-phosphoric acid — in which the double-bonded oxygen can also be replaced by thio and imino — has also been observed they were detected mainly on the basis of the electrophilic nature of the phosphorus. 

This conclusion has been drawn by Moffatt and Khorana,2 based on limited data. A subsequent, more detailed study [R. K. Ledneva, N. N. Preobrazhenskaya, Z. A. Shabarova, and M. A. Prokof ev, Molek. Biologiya, 5, 264 (1971)] clearly shows an unexpected decrease in the rate of the acid hydrolysis of the phosphor-amidates derived from strong amines. If a similar order of reactivities exists for the pyrophosphate synthesis, the phosphomorpholidate derivative seems close to being the most active. 

Metal ions have been shown to catalyze the hydrolysis of phosphate esters, phosphoric and phosphonic acid halides, and various phosphoric acid anhydrides including acyl phosphates, pyrophosphate derivatives, and ATP. 

As is unfortunately true for many investigations, the studies reflected by die data shown in Fig. 13.18 did not include analysis for transformation products. Therefore, we may only speculate regarding reaction mechanisms. Nevertheless, we may conclude that when dealing with the hydrolysis of phosphoric and thiophosphoric acid derivatives, as well as with other phosphorus-containing hydrolyzable functionalities (see Fig. 13.19), one has to be aware that various reaction mechanisms may apply. Consequently, depending on the environmental conditions prevailing, product distribution, at least with respect to intermediates formed, may vary considerably. 

The phosphoric acid esters of diacyl glycerides, phospholipids, are important constituents of cellular membranes. Lecithins (phosphatidyl cholines) from egg white or soybeans are often added to foods as emulsifying agents or to modify flow characteristics and viscosity. Phospholipids have very low vapor pressures and decompose at elevated temperatures. The strategy for analysis involves preliminary isolation of the class, for example by TLC, followed by enzymatic hydrolysis, derivatization of the hydrolysis products, and then GC of the volatile derivatives. A number of phospholipases are known which are highly specific for particular positions on phospholipids. Phospholipase A2, usually isolated from snake venom, selectively hydrolyzes the 2-acyl ester linkage. The positions of attack for phospholipases A, C, and D are summarized on Figure 9.7 (24). Appropriate use of phospholipases followed by GC can thus be used to determine the composition of phospholipids. 

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