Of phosphorate esters

Fig. 32. Stepwise preparative desorption chromatography of phosphoric esters of thiamine on CS-KU-2 cellosorbent /) highly phosphoric thiamine esters, 2) thiamine diphosphate, 3) thiamine monophosphate, 4) thiamine, 5) impurities...

Fig. 33. Stepwise preparative desorption chromatography of phosphoric esters of adenosine on CS-AV-17 cellosorbent 1) adenine, 2) adenosine, 3) adenosine monophosphate, 4) adenosine diphosphate, 5) adenosine triphosphate...

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. 

All arguments for the metaphosphate mechanism appear persuasive only when considered together since individual arguments could also apply to other hydrolysis mechanisms of phosphoric esters. 

The highly electrophilic character of the POf ion would suggest a very unselective phosphorylation behavior. For example, the ratio of alkyl phosphate to inorganic phosphate obtained in hydrolyses of phosphoric esters in water/alcohol mixtures should reflect the molar ratio of water and alcohol. This is indeed found in numerous cases, e.g. in the hydrolysis of phenyl and 4-nitrophenyl phosphate monoanions 97) or of 4-nitrophenyl phosphate dianions 65) at 100 °C in methanol/ water mixtures of various compositions, as also in the solvolysis of the acetyl phosphate dianion at 37 °C 97) or of phosphoenol pyruvate monoanions 82). Calculations of the free energy of the addition reactions of water and ethanol to the POf ion support the energetic similarity of the two reactions 98) (Table 4). 

The alcoholysis of the cyclic phosphate of catechol by alditols can lead, after acid hydrolysis of intermediate, cyclic phosphates, to the selective formation of phosphoric esters of the primary hydroxyl groups in the alditols. Thus, erythritol and D-mannitol afford, after chromatographic purification of the reaction products, their 1-phosphates in yields of 31 and 38%, respectively.217 The method was used to convert riboflavine into riboflavine 5 -phosphate.218 1-Deoxy-1-fluoro-L-glycerol has been converted into the 3-(dibenzyl phosphate) in 54% yield by selective reaction with dibenzyl phosphorochloridate. 219... 

The reagent scheme used in the pilot plant included oxalic acid-acidified silicate Na2SiF6 gangue depressant system and collector composed of a mixture of phosphoric esters and alkyl sulphate modified with mineral oil. The metallurgical results obtained are presented in Table 23.5. 

Protection of phosphoric esters is particularly required for nucleotide synthesis, where some interesting applications of photosensitive groups. 

The occurrence of phosphoric ester groups at 0-9 is long established, as Neu5Ac9P was recognized as the condensation product of enolpyruvate phosphate (PEP) and ManNAc 6-phosphate in the biosynthetic pathway of sialic acids (see Section V,l). 

In the late fifties, the N. I.H. started the Visiting Program under this, young scientists were invited to work for one or two years at the Institutes under the direction of staff members. Dr. Fletcher actively participated in this program. It was as a Visitor in Dr. Fletcher s laboratory that Dr. Donald L. MacDonald became interested in the preparation of phosphoric esters of carbohydrates, and his work eventually led to the MacDonald method of synthesizing glycosyl phosphates. 

Full references to this work may be obtained from the Annual Reports of the Chemical Society, especially vol. xxvi, 235, 1929 also The Significance of Phosphoric Esters in Metabolism," R. Robison, Oxford Univ. Press, 1933. 

Alkaline phosphatase Most tissues Hydrolysis of phosphorous esters... 

The solution should be neutral before distillation. The presence of hydrogen chloride promotes decomposition of phosphoric esters into phosphoric acid and alkenes. The benzene solution should not be washed with alkaline reagents, such as sodium carbonate solution, since alkaline reagents also cause decomposition during distillation. 

Jachimowicz claimed to have synthesized 5-phosphoadenosine (in poor yield) by direct phosphorylation of adenosine with phosphorus oxychloride in pyridine, but Bredereck showed that a mixture of phosphoric esters of adenosine actually results, as might have been anticipated. Levene and Tipson succeeded in synthesizing 5-phospho-adenosine (in poor yield) by phosphorylation of 2,3-diacetyl-adenosine to give AT-phos-pho 5-phospho-2,3-diacetyl-adenosine, followed by deacetylation by alkali, and removal by acid-hydrolysis of the labile phospho group attached to nitrogen. (This synthesis was confirmed by Bredereck, et al. ) In a similar manner they phosphorylated 2,3-isopropylidene-adenosine to iV,5-di-phospho-2,3-isopropylidene-adenosine from which the acid-labile iV-phospho and isopropylidene groups were hydrolyzed, giving 5-phospho-adenosine. 

Various studies of transesterification of phosphorous esters have been reported. The hexaco-ordinate phosphorus anion (78) has been prepared ... 

In nonenzymic substitution reactions of phosphoric esters and anhydrides, it is generally recognized that a diversity of mechanisms is allowed and that the... 

Established in Manchester, Todd continued research on vitamin E and the constituents of Cannabis. He had many wartime commitments, including research on chemical defence and antimalarials, and was a member of the British team on penicillin. He was, however, able to begin the work whose ultimate objective was the synthesis of the nucleotide coenzymes, several of which are closely related to the B vitamins, and potentially leading to a study of the nucleic acids. Attention was directed initially to each of the components, the heterocyclic bases, the nucleosides, and the chemistry of phosphoric esters. This broad strategic plan,3 begun in Manchester, was continued and expanded when Todd was appointed to the Chair of Organic Chemistry in Cambridge in 1944. 

Experimental conditions can often be varied within wide limits. For instance, yields from cyclohexane (which has been favored for study because it does not produce isomers) are substantially constant between —40° and +70° if the ratio of the reactants is invariant.164 Also presence of the products has no influence on the yield. Use of air in place of oxygen greatly reduces the rate of reaction. However, the temperature and partial pressure of oxygen do appear to influence the occasional formation of phosphoric ester dichlorides.159,162 Small amounts of diphosphorylated compounds may also appear as byproducts.165... 

The reaction of phosphorous esters and amides with polyhalogeno-methanes has been studied and used in a synthesis of phosphates. The reaction of diphenyl phosphorochloridate (103), produced in situ from diphenyl phosphonate and carbon tetrachloride, has been studied with various diamines. ... 

These proteins catalyze the addition or elimination of water to or from a substrate molecule. The carboanhydrases catalyze the hydration of CO2, peptidases and esterases the hydrolysis of carboxylic acid compounds, and phosphatases the cleavage of phosphoric esters. The active centers of hydrolytically active enzymes often contain Zn ions. Other metal ions in some of these enzymes are Mn, Ni ", Ca " and Mg. ... 

Rey, J. G. 1895. Naunyn-Schmiedeberg s Arch, exptl. Pathol, u. Pharmakol. 36, 295-305. Robison, R. 1932. The Significance of Phosphoric Esters in Metabolism. New York University Press, New York. 

Phosphorus-based (meth)acrylates have been the subject of extensive research in recent years, mainly due to the properties brought by the phosphorus atom, which can be used for different purposes. Most of the prepared monomers are phosphonated esters, whereas only limited numbers of phosphoric esters have been reported in the literature. This can be explained by easier hydrolysis of the latter in comparison with the phosphonate derivatives. Concerning the synthesis methodology, free radical polymerization and photopolymerization have been the most investigated. Some examples... 

TABLE IV-27. Slope of the Dependeftce of the Distribution Coefficient on the Concentration of the Added Reagent for Mixtures of Phosphorous Esters, Amides, Alcohols and Ketones with TTA. l... 

Koyama, M., Hayakawa, J., Onodera, T., Ito, K., Tsuboi, H., Endou, A., Kubo, M., Del Carpio, C.A., Miyamoto, A. Tribo-chemical reaction dynamics of phosphoric ester lubricant additive by using a hybrid tight-binding quantum chemical molecular dynamics method. J. Phys. Chem. B 110, 17507-17511 (2006). doi 10.1021/jp061210m... 

---