Phosphorus oxides and acids

It is noteworthy that Korobeinichev and co-authors (Korobeinichev et al., 1999d) measured concentration profiles of phosphorus oxides and acids PO, PO2, HOPO, HOPO2, and (HO)sPO in the flame that are the key flame species responsible for H and OH catalytic recombination. In the same work the authors demonstrated that the same chemical processes are responsible for both promotion and inhibition. 

These reactions are involved in the catalytic recombination cycles of H atoms with the formation of Hz. It is these reactions that are responsible for the rise in the inhibition effectiveness with increasing of ( ). Under the catalytic recombination responsible for scavenging of radicals in OPC-doped flames, all the authors meant reactions involving phosphorus oxides and acids (PO, PO2, HOPO, and HOPO2). It was assumed that organophosphorus combustion intermediates play a negligible role in the inhibition processes. However, in these specific flames reactions of OPCs with active species are of importance. 

Twarowski, A. (1993a). The influence of phosphorus oxides and acids on the rate of H + OH recombination. Combustion and Flame, Vol. 94, pp. 91-107 ISSN 0010-2180... 

Phosphorus Oxides and Oxyacids. The principal oxides are related to the acids which they yield when dissolved in H2O in the following manner ... 

The old phosphorus boxes contained preparations which absorbed moisture from the air with the evolution of heat. The resulting rise of temp, favoured combustion. For example, the mixture of yellow and red phosphorus, and phosphoric and phosphorous oxides and acids, obtained by blowing a jet of air into a flask with some warmed phosphorus, may ignite when exposed to moist air. The phosphoric oxides keep the phosphorus in a fine state of subdivision. J. Pelouze obtained a luminous mixture by melting phosphorus with phosphoric oxide, or calcined magnesia, or lime. M. Saltzer melted phosphorus with about one-third its weight of wax sent a jet of air into the flask until the phosphorus inflamed and then closed the flask. E. Benedix fused a mixture of powdered cork, beeswax, phosphorus, and naphtha. The mass fired spontaneously at 20°, or at a lower temp, if breathed upon. 

The toxicokinetics of white phosphorus smoke are likewise unknown. White phosphorus smoke is primarily oxides and acids of phosphorus, with some residual unbumt white phosphorus (refer to Chapter 3 for a detailed description of the composition of white phosphorus smoke). The fates of airborne white phosphorus, and the phosphorus oxides and phosphorus-containing acids originating from the combustion of white phosphorus, are largely unknown. 

White Phosphorus Smoke. No studies were located regarding absorption in humans or animals after inhalation exposure to white phosphorus smoke. White phosphorus smoke probably contains some residual unburnt white phosphorus (see Chapter 3 for composition information). Human serum concentrations of phosphate (relevance to absorption of white phosphorus smoke is unknown) following occupational inhalation exposure to white phosphorus are discussed in Section 2.3.3 (Metabolism). Health effects observed after inhalation of white phosphorus smoke are most likely portal of entry effects, and, therefore, do not indicate that absorption of white phosphorus occurred. However, the oxides and acids of white phosphorus that occur in the smoke are probably absorbed to an unknown degree. 

The persistence of elemental phosphorus in the air is very short due to oxidation to phosphorus oxides and ultimately to phosphorus acids. However, the particulate phosphorus aerosol may be coated with a protective oxide layer that may prevent further oxidation and extend the lifetime of particulate phosphorus in air. Both wet and dry deposition remove unreacted elemental phosphorus and the degradation products from the air. Similarly, elemental phosphorus oxidizes and hydrolyzes in water and in soil. A small amount of elemental phosphorus is lost from soil and water by volatilization. 

Phosphorus exists mostly in the phosphate form in the general environment. The levels of phosphorus determined in most environmental samples are reported as total phosphorus and do not distinguish between elemental phosphorus and its compounds. However, elemental phosphorus is far more toxic than other oxidized phosphorus states (oxides and acids of phosphorus). This profile reports the level of elemental phosphorus and not total phosphorus in environmental samples. 

Wamock 1972). Elemental phosphorus quickly oxidizes and hydrolyzes in air and in aerobic zones of water and soil to produce mainly oxides and acids of phosphorus, except when covered by a protective coating of phosphorus oxides (Bohn et al. 1970 Bullock and Newlands 1969 EPA 1991 Lai and Rosenblatt 1977a Rodriguez et al. 1972 Spanggord et al. 1985 Zitko et al. 1970). However, elemental phosphorus reaching the anaerobic zones of sediment and soil may persist for periods of 10-10,000 years (Richardson 1992 Spanggord et al. 

Rearrangement of acyl and halo groups are the most common reactions of triazoles with functions on nitrogen. The chemistry of 4-hydroxytriazoles , in effect Af-oxides, has been less extensively studied than that of triazolinones. The N—O bond is cleaved by phosphorus halides and acidic anhydride but not by oxidation with permanganate or by alkaline bromination (70jpr610). 

The Oxides and Acids of Arsenic. Arsenic trioxide (arsenious oxide, AS4OP,) is a white solid substance which sublimes readily, and is easily purified by sublimation. Its molecules have the same structure as phosphorus trioxide, shown in Figure 21-4. It is a violent poison, and is used as an insecticide and for preserving skins. 

Discuss key features of Group 5A(15), especially patterns in oxidation state, oxide acidity, and hydride and halide structures and describe the nitrogen and phosphorus oxides and oxoacids ( 14.6) (EPs 14.48-14.58)... 

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