Phosphorus tri iodide

This is a modification of Method 5, iodine being added to a mixture of red phosphorus and ethanol phosphorus tri- iodide is thus formed m situ, and readily reacts with the ethanol, giving ethyl iodide and phosphorous acid (p. 96). 

Preparation.—Two new synthetic routes to simple iodo-phosphines have appeared this year. Thus phosphorus tri-iodide (8) is produced in fairly good yield when the iodides of lanthanum, strontium, or europium are treated with the corresponding phosphates.14 Tetraiododiphosphine (9) is formed in 75—80% yield, by the reaction... 

Phosphorus tri-iodide under similar conditions gives the additive compound CrOgClg.PIs, which is a purplish-red powder when dry. It is decomposed by water, thus ... 

Heating with hydriodic acid or phosphorus tri-iodide in sealed tubes, decomposes arseno-compounds to hydrocarbons, arsenious iodide, and elemental arsenic. Sulphur gives arylarsenious sulphides, but an excess of the element at higher temperatures may cause decomposition ... 

The effect of hydriodic add is increased by the addition of red phosphorus. Under these conditions, during the course of the reaction, the liberated iodine unites with the phosphorus to form phosphorus tri-iodide ... 

NOTE.—An excess of the alcohol is usually taken in preparing alkyl halides by the method illustrated above. The phosphorus and iodine are used in the proportions necessary to form phosphorus tri-iodide, PI3. The chief reaction which takes place is represented by the following equation ... 

Directions (a) Place one crystal of iodine, 2 or 3 mm. in diameter, on not more than twice its volume of red phosphorus in an evaporating dish. Let one drop of water from the end of a glass rod fall upon the mixture. Marked action will usually take place within a minute. If it does not, the bottom of the dish may be warmed very slightly. Phosphorus tri-iodide is formed. (1) Write an equation for the reaction. After the reaction is completed, add another drop of water and blow across the top of the dish. (2) What appeared ... 

Discussion Phosphorus tri-iodide has already been prepared by the direct union of phosphorus and iodine in Experiment 82. Two sets of halides would be expected corresponding to the two valences in which phosphorus appears in combination. All of these compounds are known with the exception of phosphorus penta-iodide. Since phosphorus is a distinctly acid-forming rather than base-forming element, its halides may be completely hydrolyzed in water. 

The reactions of phosphorus tri-iodide with ethers to give complex intermediates (16), which decompose to give tetraiododiphosphine and iodine, are controlled by the effect of steric and electronic factors in the ether upon the equilibria shown in Scheme 3. Ring-opening reactions... 

Phosphorus tri-iodide and diphosphorus tetraiodide cleanly reduce a-bromo-and a -iodo-ketones to ketones.a -lodo-ketones are deiodinated by thiols and... 

Similarly, new reagents have been reported for the dehydration of aldoximes to nitriles. Thus, sulphuryl chloride fluoride, triphenylphosphine under controlled potential electrolysis, and phosphorus tri-iodide effect this transformation under mild conditions. The latter reagent, like diphosphorus tetraiodide (c/. Vol. 4, p. 179), also effects the conversion of primary aliphatic nitro-compounds into nitriles, as does sodium hypochlorite under phase-transfer catalysis and... 

By reduction of iron phosphate in hydrogen, or by passing vapours of phosphorus trichloride, tribromide, or tri-iodide over reduced iron at red heat, Granger obtained 12 grey prismatic crystals of composition... 

Ru(OH)Cls] - + 3H2O + 103 where the rate-determining step is the reduction of ruthenium(iv) by the amine with rapid re-oxidation of the metal complex by the oxidant. The oxidation of iodide by isopolymolybdic acids in the presence of germaniumfiv) and phosphorus(v) has been reported, the two-stage reactions involving the formation of a Ge " (or P ") complex with the molybdate, followed by a secondary reaction of this intermediate with I to yield the blue heteropolyacid. The two-electron reaction of indium(i) with tri-iodide ions,... 

B. Aryl Derivatives.—The Ph3P=N group imparts high nucleophilic reactivity to the tervalent phosphorus atom in A -(diphenylphosphino)tri-phenylphosphazene, Ph3p=N PPha- Ready reactions occur with methyl iodide, phosphorus(in) halides, and bromine ... 

Several methods for the preparation of the parent compound in this system, tris(trimethylsilyl)phosphite, have been reported.114 118 The application of this and related reagents in reaction with alkyl halides has been reported and used for the preparation of a variety of phosphonic acid analogues of phospholipids.114119-124 Interestingly, alkyl chlorides appear to be more reactive with the silyl reagents than do alkyl iodides, a reversal of the normally observed trend with alkyl esters of the phosphorus acids. (The particular use of silyl phosphorus reagents for the synthesis of biologically significant compounds has... 

Studies on the synthesis of [l,2,4,3]triazaphospholo[l,5-tf]pyridines have been reported by Schmidpeter et al. <1993JPR458, 1994PS381, 1995ZNB558>. The reaction pathway starts from 2-aminopyridine 147 which is first subjected to an Anamination reaction to give 1,2-diaminopyridinium iodide 148, and this compound is treated with tris-dimethylaminophosphine to yield the five-membered phosphorus-containing heterocycle 149. 

X-Ray.—The crystal and molecular structure of tri-o-tolylphosphine, its oxide, sulphide, and selenide (125) have been compared. The mean P—C bond lengths appear to be determined by the n-electron density along the P—C bond and intramolecular steric interactions, d-Orbital participation was considered to be of little importance.152 X-Ray diffraction established the structure of diphosphinofumarate (126)153 and showed that the phospholanium iodide (127) has an envelope ring with the methyl group at the point of the flap.154 The bicyclic phosphonium bromide (128) has a distorted half-chair phosphorus-containing ring, one of the P—C bonds in the... 

The chemistry of the isocyanides began when, in 1859 Lieke formed allyl isocyanide from allyl iodide and silver cyanide, and when, in 1866 Meyer ° produced in the same way 1-isocyano-l-desoxy-glucose. In 1867, Gautier used this procedure to prepare alkylisocyanides, and Hofmann introduced the formation of isocyanides from primary amines, chloroform, and potassium hydro-xyde. Gautier also tried to prepare an isocyanide by dehydrating an amine formiate via its formylamine using phosphorus pentoxide, but this process produced no isocyanide. Gautier had not yet realized that acidic media destroyed the isocyanides. 

---