Arsoniums

The PFg ion can be determined by precipitation with nitron or tetraphenyl-arsonium chloride (69). 

Other methods for preparing tertiary arsiaes have been employed, but they have limited usefiilness. These methods include the cleavage of quaternary arsonium compounds (68), the cyclodehydrohalogenation of haloarsines (69), the reaction of dia2onium salts with arsenic trichloride in the presence of a metal such as 2inc or iron (70), and the disproportionation of halo- or dihaloarsines (71). 

Arsonium salts have found considerable use in analytical chemistry. One such use involves the extraction of a metal complex in aqueous solution with tetraphenyiarsonium chloride in an organic solvent. Titanium(IV) thiocyanate [35787-79-2] (157) and copper(II) thiocyanate [15192-76-4] (158) in hydrochloric acid solution have been extracted using tetraphenyiarsonium chloride in chloroform solution in this manner, and the Ti(IV) and Cu(II) thiocyanates deterrnined spectrophotometricaHy. Cobalt, palladium, tungsten, niobium, and molybdenum have been deterrnined in a similar manner. In addition to their use for the deterrnination of metals, anions such as perchlorate and perrhenate have been deterrnined as arsonium salts. Tetraphenyiarsonium permanganate is the only known insoluble salt of this anion. 

Arsonium Ylides. Arsonium ylides were first prepared by reaction between an arsonium halide and phenyUithium. Thus methyitriphenyiarsonium iodide [1499-33-8], C H gAsI, and phenyUithium give tripbenylarsonium metbylide [19365-61-8], C H yAs ... 

In this case the ylide was not isolated but allowed to react with ben2ophenone to give, after hydrolysis with hydrochloric acid, 1,1-diphenylethylene, diphenylacetaldehyde, and triphenylarsine (160). An excellent method for preparing arsonium ylides involves the reaction between a stable dia2o compound and triphenylarsine in the presence of a copper catalyst such as bis(acetylacetonato)copper(II) (161). Rather than a dia2o compound, an iodonium yhde can be used again a copper catalyst is necessary for an optimum yield of product. An example of the use of a dia2o compound is shown in the formulation of triphenyl arsonium 2,3,4-triphenylcyclopentadienyLide [29629-32-17, C H As ... 

FYedictably, fluoroketones undergo olefination reactions with more reactive arsonium ylides [35] (equation 28). 

Numerous tetrahedral halogeno complexes [T1" X4] (X = Cl, Br, I) have been prepared by reaction of quaternary ammonium or arsonium halides on TIX3 in nonaqueous solution, and octahedral complexes TI "X< ] (X = Cl, Br) are also well established. The binuclear complex Cs3[Tl2"Cl<)J is an important structural type which features two TlCls octahedra sharing a common face of 3 bridging Cl atoms (Fig. 7.9) the same binuclear complex structure is retained when Tl " is replaced by Ti ", V ", Cr " and Fe " and also in K3W2CIS and CssBiily, etc. 

Of the quaternary arsonium compounds, methyltriaryl derivatives are important as precursors of arsonium ylides, e.g. 

Such ylides are unstable and react with carbonyl compounds to give both the Wittig product (p. 545) as well as AsPh3 and an epoxide. However, this very reactivity is sometimes an advantage since As ylides often react with carbonyl compounds that are unresponsive to P ylides. Substituted quaternary arsonium compounds are also a useful source of heterocyclic organoarsanes, e.g. thermolysis of 4-(1,7-dibromoheptyl)trimethylarsonium bromide to l-arsabicyclo[3.3.0]octane ... 

Vasishtha [56] also reportedp-acetyl benzylidene triphenyl arsonium ylide radically initiated bulk polymeriza-... 

Reaction of adsorbed inhibitors In some cases, the adsorbed corrosion inhibitor may react, usually by electro-chemical reduction, to form a product which may also be inhibitive. Inhibition due to the added substance has been termed primary inhibition and that due to the reaction product secondary inhibition " . In such cases, the inhibitive efficiency may increase or decrease with time according to whether the secondary inhibition is more or less effective than the primary inhibition. Some examples of inhibitors which react to give secondary inhibition are the following. Sulphoxides can be reduced to sulphides, which are more efficient inhibitorsQuaternary phosphonium and arsonium compounds can be reduced to the corresponding phosphine or arsine compounds, with little change in inhibitive efficiency . Acetylene compounds can undergo reduction followed by polymerisation to form a multimolecular protective film . Thioureas can be reduced to produce HS ions, which may act as stimulators of... 

It is well known that aziridination with allylic ylides is difficult, due to the low reactivity of imines - relative to carbonyl compounds - towards ylide attack, although imines do react with highly reactive sulfur ylides such as Me2S+-CH2-. Dai and coworkers found aziridination with allylic ylides to be possible when the activated imines 22 were treated with allylic sulfonium salts 23 under phase-transfer conditions (Scheme 2.8) [15]. Although the stereoselectivities of the reaction were low, this was the first example of efficient preparation of vinylaziridines by an ylide route. Similar results were obtained with use of arsonium or telluronium salts [16]. The stereoselectivity of aziridination was improved by use of imines activated by a phosphinoyl group [17]. The same group also reported a catalytic sulfonium ylide-mediated aziridination to produce (2-phenylvinyl)aziridines, by treatment of arylsulfonylimines with cinnamyl bromide in the presence of solid K2C03 and catalytic dimethyl sulfide in MeCN [18]. Recently, the synthesis of 3-alkyl-2-vinyl-aziridines by extension of Dai s work was reported [19]. 

Further organic storing materials Phenyl bromide [14], pyridine, 1 -picoline, 2,6-lutidine [15-17] Arsonium salts [18, 19] Phosphonium salts [20] Pyridinium bromides [21] Aromatic amines [22] Urotropin-bromine adduct [23] Pyridinium and sulfonium salts [24] Propionitril [25]... 

Arenediazonium salts also react with stabilized phosphonium, arsonium, pyridinium, and sulfonium ylides (12.111) in acetonitrile, yielding via the azo-onium salt (12.112) the azo-onium ylide (12.113, yellow to red), and in some cases the for-mazane (12.114) (Froyen and Juvvik, 1992). 

Beck, W. and Noth, H. (1984) Rontgenstruktur von tetraphenylarsonium-tetraazidoaurat(III). Chemische Berichte, 117, 419 Beck, W., Klapotke, T.M., Kliifers, P., Kramer, G. and Rienacker, C.M. (2001) X-Ray crystal structures and quantum chemical calculations of tetraphenyl-arsonium tetraazidoaurate(III) and azido... 

Zeller, E., Beruda, H., Kolb, A., Bissinger, P., Riede, J. and Schmidbaur, H. (1991) Change of coordination from tetrahedral gold-ammonium to square-pyramidal gold-arsonium cations. Nature, 352, 141-143. 

At present there is no more than indirect evidence for the existence of the halogeno-halothiophosphoric acids and the dibromo compound. So the unsoluble nitron dibromo-phosphate precipitates in case of the partial hydrolysis of POBr3 in acetone and in presence of nitron (5). Further the partial hydrolysis of PSCI3 and PSCI2F in presence of big cations, such as tetraphenylphosphonium or -arsonium yields stable salts (22), which suggests the primary formation of the free acid in the solution ... 

Curve 1 in Fig. 5 gives an example of the oscillation of membrane current observed with the liquid membrane system as in Eq. (3) by applying a constant AFwi-w2 of —0.48 V and measuring the time course of the current through the LM, /wi-w2- The cell used was the same as that used for the measurement of the potential oscillation, except a tetraphenyl-arsonium ion selective electrode [26,27], TPhAsE, was employed as a reference electrode in LM of NB ... 

While the validity of these assumptions has been criticized, that adopted by A. J. Parker has received the widest acceptance, i.e. that tetraphenyl-arsonium tetraphenylborate (Ph4AsPh4B),... 

Horner has extended this reaction to the electrochemical reduction of optically active arsonium salts (68, X = As), which also undergo cleavage with retention of stereochemical configuration at arsenic M 65). This is a convenient synthetic route of optically active arsines of known configuration. 

This procedure is generally unsatisfactory for tetraphenyl-arsonium salts because of coprecipitation of tetraphenylarsonium triiodide. 

Functions [R2Au] are also present in the large family of gold(i) complexes of phosphonium, arsonium, and sulfonium ylides . Section 2.05.6 is dedicated to this class of complexes, where dinuclear compounds with gold in the oxidation state +2 are also common. 

Using the 2-pyridylazoresorcinol-tetraphenyl-arsonium chloride system a concentration of 1 pg/1 could be determined with relative standard deviation of 7%. 

Vanadium complexed with tetraphenyl-arsonium chloride and tetramethylene dithio-carbamate, extracted with chloroform... 

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