Phosphorus oxidation numbers

Historically, where the central element forms oxoacids in two oxidation numbers, the higher state is indicated by the suffix -ic (as in phosphoric acid, H3PO4, phosphorus oxidation number +5), and the lower state by the suffix -ous (as in phosphorous acid, H3PO3, phosphorus oxidation number +3.)... 

Olefin synthesis starts usually from carbonyl compounds and carbanions with relatively electropositive, redox-active substituents mostly containing phosphorus, sulfur, or silicon. The carbanions add to the carbonyl group and the oxy anion attacks the oxidizable atom Y in-tramolecularly. The oxide Y—O" is then eliminated and a new C—C bond is formed. Such reactions take place because the formation of a Y—0 bond is thermodynamically favored and because Y is able to expand its coordination sphere and to raise its oxidation number. 

What is the oxidation number of phosphorus in sodium phosphite, Na3P03 In the dihydrogen phosphate ion ... 

Strategy First look for elements whose oxidation number is always or almost always the same (rule 3). Then solve for the oxidation number of phosphorus, applying rule 4. 

SOLUTION In Na3P03, the oxidation numbers of Na and O are +1 and -2, respectively. Since this compound, like all others, is neutral, the sum of the oxidation numbers must be zero. Letting x be the oxidation number of phosphorus then,... 

Self-Test K.2A Find the oxidation numbers of sulfur, phosphorus, and chlorine in (a) H2S (b) P406 (c) CIO". 

Give the oxidation number of phosphorus in iat hits phosphorus (b) red phosphorus (c) phosphine, PH... 

H3 PO4 Phosphoric acid is a covalent compound with a net charge of zero. Each hydrogen atom has an oxidation number of+1 (Guideline 3), and each oxygen has an oxidation number of-2 (Guideline 4). Now add the contributions from these atoms 3(+l) + 4(-2) = -5. For the oxidation numbers to sum to zero (Guideline 2), the phosphorus atom of phosphoric acid must have an oxidation number of +5. 

If phosphorus pentoxide were POs, phosphorus would have an oxidation number of + 10, which exceeds its group number. The maximum oxidation number that phosphorus can have is + 5 (from group VA), and so the formula is P205. (The compound cannot be a peroxide it was named oxide. )... 

Based upon its position on the periodic table, what are the highest and lowest oxidation numbers for phosphorus ... 

Phosphorus - the atomic number is 15 and the chemical symbol is P. The name derives from the Greek phosphoros for bringing light , since white phosphorus oxidizes spontaneously in air and glows in the dark. This was also the ancient name for the planet Venus, when it appears before sunrise. It was discovered by the German merchant Hennig Brand in 1669. 

Organophosphorus compounds rarely have more than one P atom in the molecule, giving rise to a doublet for any C atom within three bonds (assuming the proton-carbon coupling has been removed) and so these compounds show clearly the connectivity of carbon atoms close to the P atom. The size of the coupling constant is dependent on the number of bonds and the phosphorus oxidation state, such that Vis the largest at about 45-150 Hz, while V and V are of the order of 10-15 Hz. 

Diacetyl (DA) is used as a flavour enhancer in the food industry and is currently manufactured from methyl ethyl ketone (MEK) in homogeneous systems via an oxime intermediate (ref.1). In principle, DA can also be manufactured by the selective oxidation of MEK and several reports have appeared in the literature which apply heterogeneous catalysts to this task (refs. 2-4). A number of reports have specified the importance of basic or weakly acidic sites on the catalyst surface for a selectively catalysed reaction and high selectivities to DA at moderate conversions of MEK have been reported for catalysts based on C03O4 as a pure oxide and with basic oxides added conversely scission reactions have been associated with acidic oxide additives (refs. 2-4). Other approaches to this problem have included the application of vanadium phosphorus oxide (VPO) catalysts. Ai (ref. 5) has shown that these catalysts also catalyse the selective oxidation of MEK to DA. Indeed this catalyst system, used commercially for the selective oxidation of n-butane to maleic anhydride (ref.6), possesses many of the desired functionalities for DA formation from MEK, namely the ability to selectively activate methylene C-H bonds without excessive C-C bond scission. 

Give the names and formulas of three compounds in which (a) nitrogen (b) phosphorus has oxidation number (i) +3 (ii) +5. 

In order to calculate the average oxidation number of phosphorus atoms in Compound 3, the final hydrolysis products of Compound 3, i.e., P, ... 

The facts mentioned above may suggest that Compound 3 has a structure of Formula 2. The average oxidation number of phosphorus atoms in Formula 2 is calculated to be +3.40. Since... 

As against a wealth of compounds involving directly bonded X3P phosphorus atoms there is a relative scarcity of compounds with phosphorus atoms of different oxidation number and/or coordination number directly linked together I l. 

An inspection of the foregoing graphic formulas shows that the oxidation number of phosphorus is the same in all three of these acids—that is, they are all phosphoric acids. The prefixes pyro- and met a- are used in naming H4P207 and HP03, respectively, while ordinary phosphoric acid (H3P04) is more properly designated as orthophosphoric acid. 

Complexes of the latter two types have been assigned seven-coordinate structures on the basis of their proton and phosphorus-31 NMR spectra even though the oxidation number of the iridium atom is 3+. 

It will be recalled that the designations, hypo-. . -ous, -ous, -ic, and per. , ic (as illustrated above with the oxy-acids of chlorine) refer to a series of acids in which the oxidation number of the central atom progresses in units of 2. Hypophosphoric acid, H4P2O6 (p. 255) is a special case in which the formal oxidation number of phosphorus is between that in the -ous acid and that in the -ic acid. 

Determine the oxidation numbers of phosphorus and chlorine in phosphorus pentachloride, PCI5. 

In this compound, the oxidation number of each chlorine atom is -1 (rule 8). To make the total of all the oxidation numbers for PCI5 equal zero, the phosphorus must have an oxidation number of + 5. To do this calculation systematically, let X equal the oxidation number of phosphorus in PCI5. Then... 

The prefixes and suffixes used in Chapter 6 can also be interpreted in terms of oxidation numbers, rather than numbers of oxygen atoms. For example, the ending -ous corresponds to the oxoacid in which the central atom has the lower oxidation state in each case, and the ending -ic corresponds to the higher oxidation state. For example phosphorous acid has phosphorus in the +3 oxidation state phosphoric acid has phosphorus in the + 5 oxidation state. Phosphorus in hypophosphorous acid has an oxidation number +1. 

Draw an electron dot diagram for PSCI3, in which the phosphorus is the central atom. Determine the oxidation number of each element, and compare with the oxidation numbers in POCI3. 

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