Phosphorus acid hydrolysable

Phosphotriesterase from P. diminuta (PTE) was found to exhibit high hydrolytic activity towards various types of tetracoordinated phosphorus acid esters. Apart from the phosphonothionate 92, phosphoric acid triesters 94 (Equation 45), °" benzenephosphonic acid diester 95 (Equation 46) ° and methyl-phenylphosphinic acid ester 96 (Equation 47) were also stereoselectively hydrolysed under kinetic resolution conditions. Of course, in the case of the latter three kinds of substrates, half of the reacting ester was irreversibly lost due to the formation of achiral phosphorus acids. 

Cambella and Antia [385] determined phosphonates in seawater by fractionation of the total phosphorus. The seawater sample was divided into two aliquots. The first was analysed for total phosphorus by the nitrate oxidation method capable of breaking down phosphonates, phosphate esters, nucleotides, and polyphosphates. The second aliquot was added to a suspension of bacterial (Escherichia coli) alkaline phosphatase enzyme, incubated for 2h at 37 °C and subjected to hot acid hydrolysis for 1 h. The resultant hot acid-enzyme sample was assayed for molybdate reactive phosphate which was estimated as the sum of enzyme hydrolysable phosphate and acid hydrolysable... 

Muhlhauser et al. [51] have discussed methods for the determination of acid hydrolysable phosphorus in sediments. 

It is sometimes useful to regard the oxy-acids produced in such hydrolyses as derivatives of nonmetal hydroxides, Thus, phosphorus acid, pro-... 

The polysaccharide readily underwent hydrolysis with dilute acid and contained only traces of nitrogen and phosphorus. The hydrolysate... 

Phosphorus compounds occur in wastewater under various forms, among which the reduced ones are predominant. The phosphorus compounds of wastewater concern not only some organic forms (natural or anthropic) but also orthophosphate ion and acid hydrolysable phosphate (condensed phosphate) (Fig. 10). 

As previously mentioned, phosphorus compounds are commonly classified into orthophosphates (PO ), acid-hydrolysable (condensed) phosphates and organic phosphates. It must be noticed that acid-hydrolysable phosphates (as pyrophosphates) are negligible in sewage [30], The general procedure illustrated in Fig. 11 includes two main steps an indirect UV-visible measurement (PO -) and a photo-oxidation step followed by a UV-visible measurement (Pgl)- First, orthophosphates are determined by spectrophotometric measurement of a phosphomolybdate complex (formed with addition of ammonium molybdate 40 gL-1) using the spectrum deconvolution method. 

The hydrolysis of tervalent phosphorus acid derivatives with two P—C bonds leads to secondary phosphine oxides (50) and with one P—C bond to phosphonus acid derivatives (51). Chlorophosphines react rapidly with water, but aminophosphines, phosphinites and phosphonites often survive a short wash with aqueous NaHC03, an effective way to remove contaminating ammonium salts in the crude products. However, aminophosphines with small substituents, e.g. dimethylaminodimethylphosphine, aryl phosphinites and phosphonites and trimethylsilyl phosphinites and phosphonites are hydrolysed too quickly for such a treatment. The hydrolyses are catalysed by acids (the hydrolyses of phosphinites and phosphonites are also catalysed by OH ) and are much faster than hydrolyses of the corresponding phosphoryl compounds [up to a factor of 10 for acid-catalysed hydrolysis of (MeO)3P compared with (MeO)3P=0 ]. Dialkyl phosphonites are rapidly hydrolysed to the monoalkyl esters (51, X = OR) in weakly acidic water, whereas hydrolyses to phosphonous acids require reflux with strong acid or base, e.g. equation 131 Bis-(dialkylamino) phosphines may also be partially hydrolysed to phosphonous acid amides (51, X = NR2). Tervalent phosphorus acid derivatives with hydrogen sulphide give secondary phosphine sulphides or phosphonodithious acids, e.g. equation 156 . ... 

Paper chromatography was in use over 50 years ago for fractionation and quantitative analysis of nucleotides in nucleic acid hydrolysates. Techniques for paper and thin-layer chromatography were developed over 30 years ago for the analysis of phosphosaccharide mixtures. [40] Thin-layer chromatography (TLC) has now generally replaced paper chromatography for the analysis of organo-phosphorus mixtures. It is usually faster and more sensitive than the latter. 

Determination of phosphorus and nitrogen content was always important in nucleic acid analysis. Purines and pyrimidines in nucleic acid hydrolysates were identified and determined quantitatively by isolation on a small scale and also with the help of various colour reactions, polarography and microbiological methods. These techniques are, almost without exception, only of historical interest today. 

The melting points of these esters are usually much lower than those of the corresponding 3 5 dinitrobenzoates their preparation, therefore, offers no advantages over the latter except for alcohols of high molecular weight and for polyhydroxy compounds. The reagent is, however, cheaper than 3 5 dinitrobenzoyl chloride it hydrolyses in the air so that it should either be stored under light petroleum or be prepared from the acid, when required, by the thionyl chloride or phosphorus pentachloride method. 

Hydrolysis of the azlactone leads to the acylaminooinnamic acid the latter may be be reduced catal3rtlcally (Adams PtOj catalyst 40 lb. p.s.i.) and then hydrolysed by hydrochloric acid to the amino acid. Alternatively, the azlactone (say, of a-benzylaminocinnamic acid) may undergo reduction and cleavage with phosphorus, hydriodic acid and acetic anhydride directly to the a-amino acid (d/ p phenylalanine). 

Constitution. Pelletierine behaves as a secondary amine and the oxygen atom of the alkaloid is present in the form of an aldehyde group, since the base yields an oxime, convertible by the action of phosphorus pentachloride into a nitrile, b.p. 104-6°/13 mm., which is hydrolysed by caustic potash in alcohol to an acid, the ethyl ester of which is Loffler and Kaim s ethyl -2-piperidylpropionate. Pelletierine is not directly oxidisable to this acid. It also yields a liquid hydrazone, b.p. 130°/20 ram., which with sodium in alcohol at 136-70° reduces to dZ-eoniine. These reactions are explained by the following formulas, in which pelletierine is represented as -2-piperidylpropionaldehyde. 

When strychnine is treated with hydrogen bromide and red phosphorus in boiling acetic acid, it is converted into a complex bromodeoxyiso-strychnine hydrobromide, (C2iH2iON2Br)a , which is hydrolysed by boiling N-sulphuric acid to isostrychnine (see above), now distinguished as I, and fsostrychnine-II, m.p. 218-9°, — 258° (EtOH), which with acetic... 

PF3, unlike the other trihalides of phosphorus, hydrolyses only slowly with water, the products being phosphorous acid and HF PF3 + 3H2O H3PO3 + 3HF. 

In the pH range 2—3.5 the phosphonate (78) hydrolyses with loss of ROH at approximately 10 times the rate of comparable esters lacking the vicinal oxime function or in which this function is methylated on oxygen. An intramolecular general-acid catalysis mechanism was proposed, but it was not possible to exclude entirely an intramolecular nucleophilic attack at phosphorus. Intramolecular attack by the vicinal dimethylamino-group takes place preferentially at carbon rather than phosphorus in the phos-phonofluoridate (79). ... 

Aliquots of ethanolic solution of Parathion were separated into decomposed insecticides and decomposed insecticide products. Among the products free p-nitrophenol, chemically bound in acidic phosphorus compounds and in non-hydrolysed neutral phosphorus compounds, was detected in the same way after specification. Saponification after removal of ether without separation of neutral and acidic compounds yielded total p-nitrophenyl equivalents. 

When magnesium sulphate was omitted from distilled water samples of phosphorus compounds, recovery was variable. Table 12.11 shows yields of a series of standards with and without the magnesium sulphate addition and with and without the final hydrolysis. The magnesium sulphate is used as an acidic solution (after addition to the seawater sample, the pH was about 3) to minimize silicate leaching from the glassware during evaporation. The acid and heating are necessary to hydrolyse any condensed phosphates in the final mixture. 

Finally we should briefly mention the purple acid phosphatases, which, unlike the alkaline phosphatases, are able to hydrolyse phosphate esters at acid pH values. Their purple colour is associated with a Tyr to Fe(III) charge transfer band. The mammalian purple acid phosphatase is a dinuclear Fe(II)-Fe(III) enzyme, whereas the dinuclear site in kidney bean purple acid phosphatase (Figure 12.13) has a Zn(II), Fe(III) centre with bridging hydroxide and Asp ligands. It is postulated that the iron centre has a terminal hydroxide ligand, whereas the zinc has an aqua ligand. We do not discuss the mechanism here, but it must be different from the alkaline phosphatase because the reaction proceeds with inversion of configuration at phosphorus. 

Treatment with hot organic solvents was the next step in the tissue fractionation, to remove lipid-phosphorous and breakdown lipid-protein interactions. In the Schneider procedure, nucleic acids were then extracted in hot dilute trichloroacetic or perchloric acid, leaving a protein residue with any phosphoprotein links still intact. This method was to become particularly useful when 3H thymidine became the preferred label for DNA in the early 1960s. For investigations where both RNA and DNA were to be examined the Schmidt-Thannhauser process was often chosen. Here the lipid-extracted material was hydrolyzed with dilute sodium hydroxide releasing RNA nucleotides and any hydroxyamino acid bound phosphorus. DNA could be precipitated from the extract but the presence in the alkaline hydrolysate of the highly labeled phosphate released from phosphoprotein complicated... 

The hydrolysis of VX and GB in hot sodium hydroxide solution and of mustard in hot water results in the formation of complex organic compounds. These molecules contain heteroatoms such as sulfur, chlorine, fluorine, and phosphorus, which, when oxidized, form acids. The excess sodium hydroxide present in the hydrolysate neutralizes these acids to form salts. For example, the following reactions are likely ... 

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