Phosphorus Iodide reductions

If it is desired to use such a reaction as a means of preparing one of the reduction products, careful study of the conditions under which the reaction takes place is necessary in order to discover under what conditions the yield of the desired compound is greatest. To obtain a satisfactory yield of allyl iodide from glycerol, the latter is distilled with phosphorus iodide. It is probable that the three hydroxyl groups are first replaced by iodine and the resulting compound then loses two iodine atoms —... 

Phosphorus is usually added when reductions are effected by hydriodic acid. It combines with the iodine liberated to form phosphorus iodide, which is converted by the water present into... 

Phosphoric acid/phosphorus potassium iodide Reductive dimerization of ketones... 

An important reason for low coordination of iodide ions is that high coordination implies a high oxidation state of the central atom, which often (but not always) means high oxidising power— and this means oxidation of the easily oxidised iodide ligands. Thus the nonexistence of, for example, phosphorus(V) pentaiodide is to be explained by the oxidation of the iodide ligands and reduction of phosphorus to the -(-3 state, giving only PI3, not PI5. 

The antibiotic 2-methylfervenulone (310) was synthesized most conveniently by treatment of 338 with dimethyiformamide-phosphorus oxychloride to afford 339, followed by acid hydrolysis to give fervenulone 340. Subsequent alkylation with methyl iodide in dimethylformamide gave 310 (78JOC469). Reaction of 339 with sodium benzyloxide gave the benzyloxy derivative 344, which on catalytic reduction with palladium-charcoal provided 340. 

Reduction of carbonyl to methylene in aromatic ketones was also achieved by (dane prepared from lithium aluminum hydride and aluminum chloride [770], by soditim borohydride in triiluoroacetic acid [841 with triethylsilane in trifluoroacetic acid [555, 777], with sodium in refluxing ethanol [842], with zinc in hydrochloric acid [843] and with hydrogen iodide and phosphorus [227], geiibrally in good to high yields. 

Very pure phosphine is formed by the hydrolysis of phosphonium iodide with water, dilute acids or dilute bases 2. 4.107,109-114) or by the reduction of phosphorus trichloride with lithium in diethyl ether 7,us-ii7) Related to the latter is a method for the preparation of phosphine, described in the patent literature, where phosphorus trichloride vapour, diluted with nitrogen, is passed through a column filled with lithium hydride mixed with an inert material, such as sand, NaCl, KCl or similar materials... 

Sulfonic acids are prone to reduction with iodine [7553-56-2] in the presence of triphenylphosphine [603-35-0] to produce the corresponding iodides. This type of reduction is also facile with alkyl sulfonates (16). Aromatic sulfonic acids may also be reduced electrochemicaUy to give the parent arene. However, sulfonic acids, when reduced with iodine and phosphorus [7723-14-0]y produce thiols (qv). Amination of sulfonates has also been reported, in which the carbon—sulfur bond is cleaved (17). Ortho-lithiation of sulfonic acid lithium salts has proven to be a useful technique for organic syntheses, but has litde commercial importance. Optically active sulfonates have been used in asymmetric syntheses to selectively O-alkylate alcohols and phenols, typically on a laboratory scale. Aromatic sulfonates are cleaved, ie, desulfonated, by uv radiation to give the parent aromatic compound and a coupling product of the aromatic compound, as shown, where Ar represents an aryl group (18). 

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... 

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... 

Tertiary phosphine groups with long alkyl chains bound directly to phosphorus or substituted at the para position of triphenylphosphine give rise to a range of interesting and potentially useful complexes. In particular these may be used to prepare polyolefin hydrogenation catalysts based on platinum(II) and palladium(II) complexes that are both more active and more selective towards reduction to monoolefins than previous catalysts based on these systems. The platinum(II) complexes are better than the palladium(II) complexes. Additionally the new phosphines are more effective than triphenylphosphine in promoting the oxidative addition of methyl iodide to trans- [Rh(PR3)2Cl(CO)]. 

Successive reduction of l,3-dimethyl-4,5,6,7-tetrahydrobenzo[c]-thiophen-4-one (Section III,C) with sodium borohydride and dehydration of the resulting alcohol with polyphosphoric acid gives the unstable 1,3-dimethyl derivative [(18) R = H] in excellent yield,35 and successive treatment of the same ketone with methylmagnesium iodide and acid gives the 1,3,7-trimethyl derivative [(18) R=Me] (Table IV) and a second compound which is reported to be a dimer. 36 When l,3-dimethyl-4,5,6,7-tetrahydrobenzo[c]thiophen-4-one is treated with a mixture of phosphorus oxychloride and dimethyl-formamide (Vilsmeier-Haack formylation), it gives compound 19, which yields 20 on being treated successively with thioglycolic acid... 

The structure XXII for rhynehophylline has been confirmed, and the relative stereochemistry at C-15 and C-20 has been elucidated, by a total synthesis (80) of (+) JV-methylrhynchophyllane (XXVI) (Marion s N-methylisorhynchophyllane), which had been prepared earlier by methyl-ation of (iso)rhynchophyllane with sodium methoxide and methyl iodide (28). The lactone (XXVII) of threo-3,4-diethyl-5-hydroxyvaleric acid was converted by reaction with phosphorus pentachloride into the corresponding S-chloroacid chloride (XXVIII), which on treatment with methylaniline gave the anilide XXIX. Reduction of XXIX with lithium aluminum hydride gave the aldehyde XXX, which slowly reacted with... 

So-called C-linked calixsugars were prepared by Wittig reaction of the calix[4]arene tetraaldehyde 33 with galactose-6- or ribose-5-phosphorus ylids (obtained in situ from the known phosphonium iodides, Figure 5)70 followed by reduction of the double bonds and deprotection of the hydroxyl groups. Thus, the tetra- and trigalactosides 34c,d (all as P-anomers) and tetra- and tri-L-lyxosides 34 (as a mixture of a- and P-anomers) were obtained. 

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... 

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