Oxy compounds of phosphorus

One characteristic of phosphoric and phosphorous acids is their tendency to undergo condensation reactions when heated, ooo (Section 12.8) For example, two H3PO4 molecules are joined by the ehmination of one H2O molecule to form H4P2O7  

How do the electron domains about P in P4O5 differ from those about P in P40]o  

Phosphoric acid and its salts find their most important uses in detergents and fertilizers. The phosphates in detergents are often in the form of sodium tripolyphosphate (Na5P30io). 

The phosphate ions soften water by binding their oxygen groups to the metal ions that contribute to the hardness of water. This keeps the metal ions from interfering with the action of the detergent. The phosphates also keep the pH above 7 and thus prevent the detergent molecules from becoming protonated. 

Most mined phosphate rock is converted to fertilizers. The Ca3(P04)2 in phosphate rock is insoluble (JCjp = 2.0 X 10 ). It is converted to a soluble form for use in fertihzers by treatment with sulfuric or phosphoric acid. The reaction with phosphoric acid yields Ca(H2P04)2  

Probably the most significant phosphorus compoimds are those in which the element is combined with oxygen. Phosphorus(III) oxide (P4O5) is obtained by allowing white phosphorus to oxidize in a limited supply of oxygen. When oxidation takes place in the 

Analyze We are given the reactants (P4S3 and O2 from air) and the products (P4O10 and SO2) for a reaction, together with their standard enthalpies of formation, and asked to calculate the standard enthalpy change for the reaction. 

Plan We first need a balanced chemical equation for the reaction. The enthalpy change for the reaction is then equal to the enthalpies of formation of products minus those of reactants (Equation 5.31). We also need to recall that the standard enthalpy of formation of any element in its standard state is zero. Thus, Affy(02) = 0. 

Comment The reaction is strongly exothermic, making it evident why P4S3 is used on match tips. 

Write the balanced equation for the reaction of P4O10 with water, and calculate Aff for this reaction using data fiom Appendix C. 

---

The oxy-acids of phosphorus and their derivatives are defined as compounds which contain both P — OH and P = 0 functions (7-9,12). Ortho-phosphoric acid, phosphorus acid, and hypophosphorous acid are well-known as the oxy-acid compounds that contain three, two, and one OH... 

German Patent 299992 (Chem Ze/iir., 1917, ii, 510) deals vitii the production of organic compounds of phosphorus. Unsaturated hydroxy-fatty acids of high molecular weight when treated with phosphorus tri- or oxy-halide yield as primary products acid... 

Compounds of tnvalent phosphorus are generally oxidized to pentavalent phosphorus denvaPves bis(fluoroalkyl) and tns(fluoroalkyl) phosphites are oxi dized to the corresponding[106, lOI] (equation 92)... 

Data from this laboratory and others8,9,10 indicate that the general procedure outlined for the synthesis of F2PX compounds may be extended to the synthesis of the oxy derivatives of pentavalent phosphorus such as F2C1P0 and Cl2FPO, but the detailed directions are not given here. The mixed oxyhalides of phosphorus, like the corresponding mixed halophosphines, have not been obtained easily in pure form from complex reaction mixtures.11,12... 

In view of the rapid toxic action and myotic effect of the dialkyl phosphorofluoridates and of the high toxicity of some of the phosphorodiamidic fluorides, we prepared2 and examined a hybrid molecule containing the essential features of each type of compound. The first to be examined was ethyl phenyl-phosphoramidofluoridate (VII). One mol. of phosphorus oxy-dichlorofluoride was added to 1 mol. of ethyl alcohol, and the resulting ethyl phosphorofluoridochloridate (which it was not necessary to isolate) was treated with aniline. 

Fluophosphoric Acid.—The tendency of fluorine to replace oxygen in oxy-acids, which is exemplified in such compounds as hydrofluo-boric acid, is shown to some extent in the acids of phosphorus. The existence of alkali fluophosphates has already been alluded to (p. 87). 

Organotin esters of the oxy- and thio-acids of phosphorus can be prepared inter alia by azeotropic dehydration of a mixture of the organotin hydroxide or oxide and the acid, or by treating a tin alkoxide or tin amide with the acids, or an organotin halide with a salt of the phosphorus acid. By using different molecular ratios of the reactants, products of different compositions can be obtained. Attempts to prepare phosphites may result in an Arbuzov rearrangement to a phosphorus(V) compound (e.g. equation 13-11).47... 

Later, American workers described the preparation of this type of compound by a method which necessitated the loss of two thirds of the fluorine concerned in the reaction. They pre-pared tetramethylphosphorodiamidic fluoride (bisdimethyl aminofluorophosphine oxide) (II) by the action of phosphorus oxyfluoride on the calculated quantity of dimethylamine. In addition, it should be emphasized that phosphorus oxyfluoride is a gas and is more difficult than the hquid phosphorus oxy-dichlorofluoride to manipulate. In Report no. 14 on fluoro-phosphonates to the Ministry of Supply it was shown that our reaction could also be apphed to the preparation of tetramethyl-... 

Phosphoranyl radicals (R4P ) are the most widely studied type of phosphorus radi-cali 200). These may be important intermediates of the reactions of phosphines with radical spedes that are potentially available in biology, e.g. thiyl (RS ), alkoxy (RO ) or alkylperoxy (RO2) radicals. The reaction of alkoxy or alkylthiyF radicals with PR3 compounds take place at close to diffusion controlled rates (ca. 10 - 10 M s" ), although BuOO reacts very much slower than BuO with R3P . An important feature of the chemistry of phosphoranyl radicals X3P-A-B is that they can undergo two types of fragmentation involving cleavage of the P-A bond (a-scission) or A-B bond (P-scission). For reactions of phosphines with oxy or thiyl radicals the two pathways lead to either substitution or oxidation products ... 

Spectra-correlation charts for salts of phosphorus oxy-acids (2-16 n) [ ], for phosphorus compounds (2-26 l) [ ], for aryl phosphoric acids (2-16 n) and for organosilicon compounds (2-16 n)... 

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. 

Reaction of (30, R = H) with phosphorus oxychloride or phosphorus oxy-bromide leads to a mixture of 2,4-dihalogeno-3-nitro- (123) and 2,3,4-trihalogeno compounds (124) in a ratio of about 2 1 (98MI3). 

Phosphorus thioxy acids and phosphorus thio acids, in w hich some or all of the oxygen atoms around the phosphorus atom in the oxy-acids are replaced by sulfur atoms, respectively, are also known (8). Physicochemical properties of selected phosphorus compounds described in Section II are shown in Table Iff. 

---