Phosphorus triiodide

Phosphorus triiodide [ 13455-01-1 ] M 411.7, m 61 . Decomposes in moist air and must be kept in a desiccator over CaCl2. It is crystallised from sulfur-free CS2 otherwise the m decreases to ca 55°. It is best prepared freshly. [J Am Chem Soc 49 307 7927 Handbook of Preparative Inorganic Chemistry (Ed. Brauer) vol I 541 7965.] HARMFUL VAPOURS. 

A student prepares phosphorous acid, H3PQ3, by reacting solid phosphorus triiodide with water. 

Glycerol gave rise to a particularly violent reaction with phosphorus triiodide. 

See Phosphorus trichloride Sulfur acids Phosphorus triiodide Sulfur acids... 

See Phosphorus tribromide Sulfur acids and Phosphorus triiodide Sulfur acids See other induction period incidents... 

Although 1,3,2-diazaphospholenium cations are usually prepared from neutral NHPs or 1,3,2-diazaphospholes via Lewis-acid induced substituent abstraction or A-alkylation, respectively (cf. Sect. 3.1.2), the group of Cowley was the first to describe a direct conversion of a-diimines into cationic heterocycles by means of a reaction that can be described as capture of a P(I) cation by diazabutadiene via [4+1] cycloaddition [31] (Scheme 4). The P(I) moiety is either generated by reduction of phosphorus trihalides with tin dichloride in the presence of the diimine [31] or, even more simply, by spontaneous disproportionation of phosphorus triiodide in the presence of the diimine [32], The reaction is of particular value as it provides a straightforward access to annulated heterocyclic ring systems. Thus, the tricyclic structure of 11 is readily assembled by addition of a P(I) moiety to an acenaphthene-diimine [31], and the pyrido-annulated cationic NHP 12 is generated by action of appropriate... 

This procedure differs from those outlined for the bromo and chloro derivatives in that an appreciable excess of (dimethyl-amino) diflu orophosphine cannot be used because it is difficult to separate from iododifluorophosphine by fractional condensation. Typically, (dimethylamino)difluorophosphine (6.38 mmol) and hydrogen iodide (12.76 mmol) are condensed into a 500-ml. reaction bulb and allowed to warm slowly to 25°. As reaction ensues, f the white solids are discolored by formation of red phosphorus triiodide which probably results from a disproportionation 3PF2I —> 2PF3 + PI3. Thus, when the products are separated by fractional condensation through —126° (methylcyclohexane slush) to —196°, an appreciable amount of... 

The phosphorus triiodide is formed in situ by the reaction 2P + 3I2---> 2PI3. 

Phosphorus azide difluoride, 4315 Phosphorus trifluoride, 4339 Phosphorus triiodide, 4636 Tetrachlorodiphosphane, 4171 Tetraiododiphosphane, 4637... 

Phosphorus tricyanide, 1343 Phosphorus trilluoride, 4339 Phosphorus triiodide, 4636 Phosphoryl chloride, 4149... 

Reaction with potassium iodide yields phosphorus triiodide ... 

EPOXIDES Diphosphorus tetraiodide. Lithium. 3-Methyl-2-selenoxo-l,3-benzothiazole. Phosphorus triiodide. Lithium. Potassium iodide-Zinc-Phos-phorus(V) oxide. Samarium(II) iodide. Sodium O.O-diethyl phosphorotelluro-ate. Triphenylphosphine hydroiodide-Triplienylphosphine diiodide. 

SULFOXIDES Chlorotrimethylsilane-Zinc. Cyanuric fluoride. Phosphorus triiodide. 

We may classify solids broadly into three types based on their electrical conductivity. Metals conduct electricity very well. In contrast, insulators do not. Insulators may consist of discrete small molecules, such as phosphorus triiodide, in which the energy necessary to ionize an electron from one molecule and transfer it to a second is too great to be effected under ordinary potentials.M We have seen that most ionic sefids are nonconductors. Finally, solids that contain infinite covalent bonding such as diamond and quartz are usually good insulators (but see Problem 7.5). 

Concentrated hydrochloric acid also dissolves the trichloride, about 100 g. of the latter dissolving in 1 litre of acid at 100° C.7 Dissolution in hydriodic acid is accompanied by evolution of heat and the triiodide is formed.8 Ethyl iodide reacts similarly.9 Double decomposition reactions occur w hen arsenic trichloride is heated with phosphorus triiodide, stannic iodide or germanium iodide, the reactions being complete.10 Similarly, potassium iodide heated with arsenic trichloride in a sealed tube at 210° C., and potassium bromide at 180° to 200° C., form respectively arsenic triiodide and tribromide.11 Stannous chloride, added to the solution in hydrochloric acid, causes reduction to arsenic (see p. 29). Arsenic trichloride may be completely separated from germanium chloride by extraction with concentrated hydrochloric acid.12 Ammonium, sodium and cobaltic chlorides react with arsenic trichloride to form additive compounds with magnesium, zinc and chromic chlorides there is no reaction.13... 

The vapour density2 is 16-1 (air = l) corresponding to the molecular formula Asl3 (15-8), but the vapour, which is yellow, generally contains the products of thermal decomposition (see below). The heat of formation, according to Berthelot,3 is (As, 8lgas) 28,800 calories and (As, 3lsona) 12,600 calories. From measurements of density and coefficient of expansion at low temperatures the molecular volume at 0° Abs. has been calculated 4 to be 98-2, a value which corresponds with that similarly derived for the molecular volume of phosphorus triiodide. 

Under high pressures and temperatures, iodine reacts with oxygen to form iodine pentoxide [12029-98-0] (44). The reaction of iodine with carbon monoxide under acidic conditions is catalyzed by palladium salts (45). Phosphorous vapor and iodine react to form phosphorus triiodide [13455-01-1]> PI3 (46). 

The aliphatic iodine derivatives are usually prepared by reaction of an alcohol with hydroiodic acid or phosphorus triiodide by reaction of iodine, an alcohol, and red phosphorus addition of iodine monochloride, monobromide, or iodine to an olefin replacement reaction by heating the chlorine or bromine compound with an alkali iodide in a suitable solvent and the reaction of triphenyl phosphite with methyl iodide and an alcohol. The aromatic iodine derivatives are prepared by reacting iodine and the aromatic system with oxidizing agents such as nitric acid, fuming sulfuric acid, or mercuric oxide. 

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