Phosphate chemistry

The steps involved in automated oligonucleotide synthesis illustrate the current use of protective groups in phosphate chemistry (Scheme 1). Oligonucleotide synthesis involves the protection and deprotection of the 5 -OH, the amino groups on adenine, guanine, and cytosine, and -OH groups on phosphorus. 

The RNA world hypothesis caused prebiotic phosphate chemistry to become an attractive research area again unfortunately, no clear evidence for a realistic nucleotide synthesis under the simplified conditions of a primitive Earth has yet appeared. Important work on nucleoside phosphorylation has, however, been done. It is important to distinguish between ... 

Pyrite is not only one of the key compounds in Wachtershauser s theory, but could also have fulfilled an important function for phosphate chemistry in prebiotic syntheses. A group in Rio de Janeiro studied the conditions for phosphate sorption and desorption under conditions which may have been present in the primeval ocean. In particular, the question arises as to the enrichment of free, soluble inorganic phosphate (Pi), which was probably present in low concentrations similar to those of today (10 7-10 8M) (Miller and Keffe, 1995). Experiments show that acid conditions favour sorption at FeS2, while a weakly alkaline milieu works in an opposite manner. Sorption of Pi can be favoured by various factors, such as hydrophobic coating of pyrite with molecules such as acetate, which could have been formed in the vicinity of hydrothermal systems, or the neutralisation of mineral surface charges by Na+ and K+. 

As much of biological phosphate chemistry appears to be subject to metal ion catalysis there is a great incentive to clarify and define much of the chemistry described above. 

M.-T. Averbuch-Pouchot and A. Durif, Topics in Phosphate Chemistry, World Scientific, Singapore, 1996. 

Furuta, T., Torigai, H., Osawa, T. and Iwamura, M. (1993) New photochemically labile protecting group for phosphates. Chemistry Letters, 1179-1182. 

Phosphorous is a five-valent element, and its natural oxide is P2O5, phosphorous pentoxide. It is a highly hygroscopic powder and readily reacts with water to form phosphoric acid (H3PO4). This acid when reacted with various aUcaline compounds forms phosphates. These and other modified compounds are linear or chain, cyclic or ring, and branch chain polymers. Because these compounds are polymeric, phosphates can provide a continuous structure and, hence, form good ceramics. The reader is referred to Topics in Phosphorus Chemistry by Westman [1] for details. Because of the variety of polymeric compounds formed by phosphorous, a systematic nomenclature is used in phosphate chemistry. 

At present, there are only a few comprehensive publications on phosphate chemistry, minerals, and materials. Notable ones are Inorganic Phosphate Materials by T. Kanazawa [Kodansha, Tokyo, and Elsevier, Amsterdam (1989)], Phosphate Minerals by J. Nriagu and P. Moore [Springer-Verlag, Berlin (1984)], and a chapter on CBPCs in Acid-Base Cements by A. Wilson and J. Nicholson [Cambridge Univ. Press, Cambridge (1993)]. Much of the background information on phosphate materials is derived from these and other phosphate chemistry books. 

The covalent bonding in the tetrahedral P04 anion may be described as the average of four resonance hybrids such as (I), giving the average structure (2) with tetrahedral (Td) symmetry. These two views of the bonding illustrate important features of phosphate chemistry. (I) shows that up to three... 

Crutchfield, M. N., Private communication, Monsanto Company Griffith, E. J., International Conference On Phosphate Chemistry. Tokyo, Japan, July, 1991. 

Unlike sulfur, phosphorus compounds are not believed to directly poison the noble metals. This may owe to the extreme difficulty of reducing phosphorus below the +3 state. Also unlike sulfur, cerium phosphate chemistry does not have a corresponding redox chemistry that can provide a secondary source of OSC. Cerium phosphates, once formed (likely from P2O5 or H3PO4 precursors), trap the ceria in the 3+ oxidation state and irreversibly poison OSC. Moreover, one cannot rule out the possibility that this may be facilitated by the noble metals thus leading to preferential poisoning of ceria in the vicinity of the noble metal particles. 

Phosphate chemistry in soils has been studied more intensively than that of any other element save nitrogen. Phosphate added to soils is first adsorbed quickly and is later fixed into increasingly less soluble states as time increases. Despite this great effort, quantitative predictions of phosphate concentrations in soil solutions are poor and no techniques have been devised to release the large amounts of unavailable phosphate in soils, nor to prevent fixation of fertilizer phosphate by soils. The uncertainties about soil phosphate chemistry and the difficulty of increasing phos-... 

New to Lite Third Edition is an enhanced emphasis on soil solution chemistry and expanded coverage of phosphate chemistry and the chemical principles of the aqueous phase. At the same time, the book has retained the dear examination of the lundarnenmls of the science of soil that has distinguished earlier editions. Complete with SI units and end-of-chapter study questions, Soil Chemistry is an excellent introductory resource for students studying this crucial topic. 

Boatner LA, Beall GW, Abraham MM, Finch CB, Huray PG, Rappaz M (1980) Monazite and other lanthanide orthophosphates as alternate actinide waste forms. In Scientific Basis for Nuclear Waste Management, vol. 2, Northrap, CJM Jr (ed) Plenum Press, New York, p 289-296 Brandel V, Dacheux N, Genet M (1996) Reexamination of uranium (IV) phosphate chemistry. J Solid State Chem 121 467-472... 

Arguably the most rapidly expanding area of research in biological phosphate chemistry over the past two or three years has been in the area of inositol phosphates. Agonist-induced stimulation of inositol-phospholipid metabolism results in hydrolysis of phosphatidyl inositol 4,5-bisphosphate... 

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