Phosphates and Phosphonates

Synthetic studies for the discovery of effective antidotes for cholinesterase inhibitors are continuing . Various reactivity studies of oximates with different functional organophosphorus compounds, such as phosphinates, phosphonates, phosphates and thiono analogues (shown in Scheme 5), have been reported . ... 

Aqueous and CI2 or C10 except C104 , yield phosphonate, phosphate and Cr in either acid or alkali, but hot, concentrated HCIO4 goes to CI2 or Cl". The reaction with HCIO3 may be explosive. 

Halogenated All l Phosphates and Phosphonates. In this important class of additives, the halogen contributes somewhat to flame retardancy although this contribution is offset by the lower phosphoms content. The halogens reduce vapor pressure and water solubHity, thus aiding retention of these additives. Efficient manufacturing processes lead to favorable economics. 

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). 

Phosphoric acid, monoalkyl phosphates, and phosphonic acids, but not dialkyl phosphates (107), can be aminoalkylated on the oxygen (108—110). 

Much effort has been placed in the synthesis of compounds possessing a chiral center at the phosphoms atom, particularly three- and four-coordinate compounds such as tertiary phosphines, phosphine oxides, phosphonates, phosphinates, and phosphate esters (11). Some enantiomers are known to exhibit a variety of biological activities and are therefore of interest Oas agricultural chemicals, pharmaceuticals (qv), etc. Homochiral bisphosphines are commonly used in catalytic asymmetric syntheses providing good enantioselectivities (see also Nucleic acids). Excellent reviews of low coordinate (coordination numbers 1 and 2) phosphoms compounds are available (12). 

Phosphoms compounds are effective flame retardants for oxygenated synthetic polymers such as polyurethanes and polyesters. Aryl phosphates and chloroalkyl phosphates are commonly used, although other compounds such as phosphonates are also effective. The phosphoms compounds can promote char formation, thereby inhibiting further ignition and providing an efficient thermal insulation to the underlying polymer. 

The phosphates and phosphonic acids appeared as white zones on a pink background (Fig. 1 A). Figure 1B is a reproduction of the reflectance plots (X = 480 nm). Detection limits of 50 ng have been found for POl and PaOj". In the case of PsOl and P3O10 the detection limits were 125 ng per chromatogram zone. 

Fig. 1 A) Separation of phosphates and phosphonic acids B) absorption plots of track 5 and track 8. PjOl (1), PjOio (2), P20t (3), POl (4), mixture 1 (5), aminotrimethylene-phosphonic acid (6), l-hydroxyethane-l,l-diphosphonic acid (7), mixture II (8).

Me3SiBr, CH3CN, 1-2 h, 25°, >97% yield. This reagent is also useful for the cleavage of ethyl phosphates and phosphonates. ... 

Monocyclohexyl phosphates and phosphonates can be cleaved by a two-step process in which the ester is treated with an epoxide such as propylene oxide to form another ester, which, upon treatment with base, releases the cyclohexyl alcohol. ... 

There are many parallels between phosphates and sulfates of aliphatic alcohols. Both types of surfactants contain ester bonds undergoing hydrolysis in acid solutions. In that case the starting materials are received once more. By dry heating of the salts above a temperature of 140°C destruction will occur forming the corresponding alkenes and an inorganic acid salt. In the same way as sulfonic and sulfinic acids are formed by C-S bonds, C-P bonds lead to phosphonic and phosphinic acids. 

Phosphates and phosphonates are valuable contents of cleaners used for technical purposes especially when anticorrosive behavior is also required. Phosphoric acid esters are a component of aqueous cleaning compositions for printed circuit boards [212]. 

The analysis of phosphates and phosphonates is a considerably complex task due to the great variety of possible molecular structures. Phosphorus-containing anionics are nearly always available as mixtures dependent on the kind of synthesis carried out. For analytical separation the total amount of phosphorus in the molecule has to be ascertained. Thus, the organic and inorganic phosphorus is transformed to orthophosphoric acid by oxidation. The fusion of the substance is performed by the addition of 2 ml of concentrated sulfuric acid to — 100 mg of the substance. The black residue is then oxidized by a mixture of nitric acid and perchloric acid. The resulting orthophosphate can be determined at 8000 K by atom emission spectroscopy. The thermally excited phosphorus atoms emit a characteristic line at a wavelength of 178.23 nm. The extensity of the radiation is used for quantitative determination of the phosphorus content. 

The chemical shift of phosphorus in phosphonates occurs in a region removed from the shift in phosphates and P n.m.r. has been used to detect phosphonates in lipids. Phosphonates have also been detected by H n.m.r. spectroscopy as P—CHg protons appear at higher field than P—O—CH2 protons. ... 

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