Arsine oxide

Trialkyl- and triarylarsine sulfides have been prepared by several different methods. The reaction of sulfur with a tertiary arsine, with or without a solvent, gives the sulfides in almost quantitative yields. Another method involves the reaction of hydrogen sulfide with a tertiary arsine oxide, hydroxyhahde, or dihaloarsorane. X-ray diffraction studies of triphenylarsine sulfide [3937-40-4], C gH AsS, show the arsenic to be tetrahedral the arsenic—sulfur bond is a tme double bond (137). Triphenylarsine sulfide and trimethylarsine sulfide [38859-90-4], C H AsS, form a number of coordination compounds with salts of transition elements (138,139). Both trialkyl- and triarylarsine selenides have been reported. The trialkyl compounds have been prepared by refluxing trialkylarsines with selenium powder (140). The preparation of triphenylarsine selenide [65374-39-2], C gH AsSe, from dichlorotriphenylarsorane and hydrogen selenide has been reported (141), but other workers could not dupHcate this work (140). 

Similar reactions on alkyl or aryl arsonites yield the arsinic acids R2AsO(OH) and Ar2AsO(OH). Arsine oxides are made by alkaline hydrolysis of R3ASX2 (or Ar3AsX2> or by oxidation of a tertiary arsine with KMn04, H2O2 or I2. 

Calcium-binding proteins, 6, 564, 572, 596 intestinal, 6, 576 structure, 6, 573 Calcium carbonate calcium deposition as, 6, 597 Calcium complexes acetylacetone, 2, 372 amides, 2,164 amino acids, 3, 33 arsine oxides, 3, 9 biology, 6, 549 bipyridyl, 3, 13 crown ethers, 3, 39 dimethylphthalate, 3, 16 enzyme stabilization, 6, 549 hydrates, 3, 7 ionophores, 3, 66 malonic acid, 2, 444 peptides, 3, 33 phosphines, 3, 9 phthalocyanines, 2,863 porphyrins, 2, 820 proteins, 2, 770 pyridine oxide, 3,9 Schiff bases, 3, 29 urea, 3, 9... 

A similar quantitative treatment of sulphoxides as hydrogen bonding acceptors has been obtained by comparing the IR frequency shift AvOH of the C—I bond in an acetylenic iodide such as IC=CI (Avc j) due to formation of a C—T complex with phenol in various bases. This investigation suggests that sulphoxides belong to the same family as carbonyls, phosphine oxides, arsine oxides and their derivatives90. 

A. Preparation.—The first reverse Wittig olefin synthesis has been reported. Triphenylphosphine oxide and dicyanoacetylene at 160 °C gave the stable ylide (1 78%) the reaction was reversed at 300 °C. No comparable reaction was observed with a variety of other activated acetylenes but tri phenyl arsine oxide gave the corresponding stable arsoranes with dicyanoacetylene (— 70 °C), methyl propiolate, hexafluorobut-2-yne, dimethyl acetylene dicarboxylate, and ethyl phenylpropiolate (130 °C). 

Considerable controversy surrounds the nature of the bonding in amine oxides and analogous phosphine and arsine oxides. These species are often depicted in textbooks as double-bonded (0=PH3, 0=AsH3) in order to rationalize the unusually short bond lengths. However, both theoretical wavefunction analysis53 and NMR... 

Several examples have been reported of rearrangements of arsine oxides (51) to esters, initiated by alkyl halides.42 43 Reactions of tertiary arsine oxides with thiols (52) cause deoxygenation.44... 

The compound is digested with nitric acid and the solution is analyzed for antimony by AA or ICP spectrophotometry (see Antimony). To determine the chlorine content a measured amount of substance is heated at 300°C and the liberated CI2 is passed into an acidic solution of KI and analyzed by iodomet-ric titration using a standard solution of sodium thiosulfate or phenyl arsine oxide and starch indicator. 

Chlorine gas may be identified readdy by its distinctive color and odor. Its odor is perceptible at 3 ppm concentration in air. Chlorine may be measured in water at low ppm by various titrimetry or colorimetric techniques (APHA, AWWA and WEF. 1999. Standard Methods for the Examination of Water and Wastewater, 20th ed. Washington DC American Pubhc Health Association). In iodometric titrations aqueous samples are acidified with acetic acid followed by addition of potassium iodide. Dissolved chlorine liberates iodine which is titrated with a standard solution of sodium thiosulfate using starch indicator. At the endpoint of titration, the blue color of the starch solution disappears. Alternatively, a standardized solution of a reducing agent, such as thiosulfate or phenylarsine oxide, is added in excess to chlorinated water and the unreacted reductant is then back titrated against a standard solution of iodine or potassium iodate. In amperometric titration, which has a lower detection limit, the free chlorine is titrated against phenyl arsine oxide at a pH between 6.5 and 7.5. 

Iodine in aqueous solution may be measured quantitatively by acidifying the solution, diluting it, and titrating against a standard solution of sodium thiosulfate, sodium arsenite or phenyl arsine oxide using starch indicator. The blue color of the starch decolorizes at the end point. The indicator must be added towards the end of titration when the color of the solution turns pale yellow. Prior to titration, iodine in the dilute acidic solution is oxidized to iodate by adding bromine water or potassium permanganate solution. Excess potassium iodide is then added. The liberated iodine is then titrated as above. 

The hypochlorite ion may be identified most distinctly by ion chromatography. Its concentration in the aqueous solution combined as CIO and molecular CI2 (which is partly formed when hypochlorite is dissolved in water) can be measured by iodometric titration. A measured volume of sodium hypochlorite solution is added to a small volume of an acidified solution of potassium iodide (in excess). Iodine liberated is titrated with a standard solution of sodium thiosulfate or phenyl arsine oxide using starch as indicator. Blue color of starch solution decolorizes at the end point. 

Elemental composition Na 15.34%, I 84.66%. Aqueous solution is analyzed for sodium by AA or ICP and for iodide ion by ion chromatography or leuko-crystal violent colorimetry (See Iodine). Alternatively, in an acidified solution of sodium hypochlorite, a measured amount of sodium iodide is titrated against a standard solution of sodium thiosulfate or phenyl arsine oxide using starch indicator to detect the end point. 

Ph3PO)2NiBr2 is very nearly regular. Arsine oxides form similar complexes (106). 

Oxygen was abstracted from phosphine oxides, phosphonates,407 arsine oxides and sulfoxides by MX5 as well as by [MX4Me] (X = C1, Br),408 and more easily by the Nb than by the Ta derivatives, to yield MOX3 adducts (equation 36 Table 21). IR indicated the following sequence for the metal s acceptor character MCI5 > MOCl3 > MOCl2Me. NMR showed that in... 

Dimethyl sulfoxide, phosphine oxides and arsine oxides 753... 

Table 28 Complexes of Dimethyl Sulfoxide and Phosphine and Arsine Oxides...

Most of the early reports of phosphine or arsine complexes are erroneous, the products being phosphine oxide or arsine oxide compounds. 

Table 41 Complexes of Actinide(rV) Compounds with Arsine Oxides...

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