Sulphides, of phosphorus

With phosphorus the reaction products vary according to the conditions. In the presence of an excess of monochloriclc, phosphorus sulphochloride and free sulphur are obtained, whereas if the monochloride is introduced into an excess of molten phosphorus, the products are the trichloride and sulphide of phosphorus, some red phosphorus also being formed.6... 

Hydrogen bromide, iodide and sulphide are oxidised to the corresponding elements, various reduction and hydrolytic products of the pyrosulphuryl chloride being formed at the same time. Phosphine also causes reduction of pyrosulphuryl chloride with production of sulphide of phosphorus.4... 

An excess of red phosphorus is mixed with finely-powdered sulphur, and the mixture heated in a wide tube, sealed at one end, in an atmosphere of carbon dioxide. The temperature is first gradually raised to 100°, and then the reaction started by stronger local heating near the surface of the mixture. When the reaction has spread through the whole mass, the tube is strongly heated until the contents begin to distil, otherwise higher sulphides of phosphorus are formed the reaction product, which consists of red phosphorus and tetraphosphorus trisulphide, is allowed to cool in the atmosphere of carbon dioxide. The trisulphide may be separated from the red phosphorus by extraction with carbon bisulphide or by distillation in an atm. of carbon dioxide, but in both cases it is somewhat impure. 

The compound is reduced slowly by hydrogen iodide, giving PI3, H2S, HC1 and sulphides of phosphorus.12 Like other halides of phosphorus it combines with dry ammonia, giving a white solid, which may contain from 80 to 60 per cent, of NH3. This product is said to contain thio-... 

Like its constituent elements, this sulphide of phosphorus dissolves very freely in CS2 (solubility 60 to 100 at ordinary temperatures). It is also moderately soluble in solvents such as benzene and toluene. 

The chemical properties are similar to those of the other sulphides of phosphorus, but the compound is less stable, and easily decomposes, giving P4S3 with separation of sulphur. 

Uses of the Sulphides of Phosphorus.—The pentasulphide of phosphorus is used to replace the oxygen of organic compounds by sulphur thus ethyl alcohol gives ethyl mercaptan, and acetic acid thioacetic acid.4 The reactions, however, are somewhat complex thus with ethyl alcohol the first product has been shown to be diethyl-dithiophosphate, SP(SH)(OEt)s, the mercaptan being produced by a secondary reaction.5 Phosphorus pentasulphide, boiling under atmospheric or other definite pressure, has been recommended for use in constant temperature baths in place of sulphur. The compound P4S3, which is one of the most stable sulphides in diy air, but resembles phosphorus in some respects, is used as a substitute for this element in the manufacture of matches.6... 

By heating ammonium chloride with sulphides of phosphorus. 

Phosphorus and Sulphur —Historical—Physical Mixtures—The System Phosphorus-Sulphur and Compounds—Tetraphosphorus Trisulphide—Diphosphorus Trisulphide — Tetraphosphorus Heptasulphide — Phosphorus Pentasulphide—Uses of the Sulphides of Phosphorus—Oxysulphides—Thio-phosphites, Thiohypophosphates and Thiophosphates. 

There are four sulphides of phosphorus, P4S5, P4S7, P4S and P4S4o- The structures of P4S7 and P4S10, the latter being the only sulphide with a structure similar to that of an oxide, were determined by Vos and Wiebenga... 

Sulphides of Phosphorus Sulphides of the formula P4S (where n = 3, 5, 7, 8, 9, or 10) have been described. These may be obtained by heating red phosphorus with sulphur in appropriate amount. 

With chloride of phosphorus it forms chloride of antimony and sulphide of phosphorus, and also sulphophosphoride of antimony (Brandimont). 

FIGURE 4.12 Molecular structures of oxides and sulphides of phosphorus. (Reprinted from Phosphorus An Outline of Its Chemistry, Biochemistry and Technology, 3rd Ed., D.E.C. Corbridge, p. 79, Elsevier, Amsterdam, 1985. Copyright 1985, with permission from Elsevier.)... 

Mix intimately in a mortar 100 g. of sodium laevulinate, 250 g. of phosphorus sulphide (1) and 50 g. of clean dry sand. Place the mixture in a flask fitted with a condenser for distillation and a receiver (2). Heat the flask with a free flame until the reaction commences, and then remove the flame. When the reaction subsides, continue the heating until distillation ceases. Wash the distillate with 10 per cent, sodium hydroxide solution to remove acidic by-products and steam distil. Separate the crude 2-methyltliiophene from the steam distillate, dry over anhydrous calcium sulphate, and distil from a little sodium. Collect the pure compound at 113° the yield is 30 g. 

Dimethylthiophene (II) Is re.adily prepared by Interaction of phosphorus sulphide and acetonylacetone (I) ... 

A"-Ray structure determinations (see Chapter 11 for details) have been reported for triphenylphosphine oxide, tri-o-tolylphosphine oxide, sulphide, and selenide, and for cw-2,2,3,4,4-pentamethyl-l-phenylphos-phetan-1-oxide (5). Electron spectroscopic studies of phosphorus oxychloride and thiophosphoryl chloride in the gaseous state, and n.m.r., i.r., and u.v. spectra of phosphine sulphides have appeared. Dipole moments have been used to define the stereochemistry of 2-cyanoethylphosphine oxides, such as (6), which is shown in its preferred conformation. 

An example of a higher resolution map from the EPMA is given in Figure 5.11, where the sample is again an archaeological specimen - a pair of shears from the same site as the specimen shown in Figure 5.10. Here the weld lines are marked by lines of sulphide and slag particles in an area depleted of phosphorus. 

Further examples of deoxygenation of epoxides by phosphine sulphides or selenides have appeared,41 as shown in Scheme 6 for simple epoxides (50). Incorporation of phosphorus into a five-membered ring appears to be responsible for the relatively rapid deoxygenations by the phosphole and A3-phospholen derivatives.41... 

The deoxygenation of some penicillin and cephalosporin sulphoxides has been accomplished by the use of phosphorus pentasulphide.53 The reactive species responsible for deoxygenation was not identified. A particularly mild method for reducing sulphoxides to sulphides involves the reaction of the sulphoxide with 2-chloro-l,3,2-benzodioxaphosphole at room temperature.536 Yields in excess of 80% were reported. 

Electron.—The determination of the molecular structure of phosphorus heterocycles by electron diffraction has been reviewed.176 The structures of trimethylphosphine oxide, and the corresponding sulphide in the gaseous phase, have been compared. The rotational freedom of the methyl group appears to be greater for the sulphide, which also has the longer P—C bonds, i.e. 181.8 pm for (144 Ch = S)and 180.9 pm for (144 Ch = O).177 The trifluoromethylphosphoranes (145) and (146) adopt the... 

Solubility of Phosphorus in Carbon Sulphide. This experiment is prepared by one student who demonstrates it to the class. (TFor/c in a jume cupboard, extinguish all burners ) Pour 2-3 ml of carbon sulphide into a small porcelain bowl and lower a small piece of white phosphorus into it. What occurs Take a small sheet of filter paper with pincers, wet it with the solution of phosphorus in carbon sulphide, and see what happens. Test the solubility of red phosphorus in carbon sulphide. 

Impubities.—rhosphorus is rarely adulterated, and the only impurities contained in it are those derived from the acid used in its preparation. Dumas considers flexibility as a characteristic of good phosphorus. Occasionally arsenic, antimony, bismuth, and some other metals have boon found in it. If the acid used contained arsenioua acid, or an oxide of antimony, these are reduced in the process of manufacture of phosphorus, and are found in it in the metallic state. A solution of phosphorus in dilute nitrio acid should give no precipitate with sulphide of hydrogen, and the precipitate procured by a barytic salt should be entirely soluble in excess of nitric acid, proving the absence of sulphur. If arsenic is present, the solution in nitrio acid deposits a black precipitate of metallic arsenic when submitted to evaporation. 

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