Secondary arsines

Reactions of primary arsines, secondary arsines and compounds having As—As bonds with organoelectrophiles... 

Primary and Secondary Arsines. Compared to the vast number of known organoarsenic compounds, relatively few primary (RASH2) and secondary (R2ASH) arsines have been described. Primary arsines are commonly prepared by the 2inc—hydrochloric acid reduction of substances containing... 

Secondary aisines, which can be synthesized by methods analogous to those used for piimaiy arsines, are obtained in good yields by the reduction of arsinic acids (44) or haloarsines (45) with amalgamated zinc and hydrochloric acid. They can also be prepared by the alkylation of primary arsenides (46) ... 

Another good method for preparing secondary arsines involves cleavage of an alkyl or aryl group from a tertiary arsine and subsequent hydrolysis of the resulting secondary arsenide (47,48) ... 

Finally, secondary arsines can be obtained by the reductive cleavage of diarsines with mercury and hydrogen iodide (49) or with hthium aluminum hydride... 

Methylarsine, trifluoromethylarsine, and bis(trifluoromethyl)arsine [371-74-4] C2HAsF, are gases at room temperature all other primary and secondary arsines are liquids or solids. These compounds are extremely sensitive to oxygen, and ia some cases are spontaneously inflammable ia air (45). They readily undergo addition reactions with alkenes (51), alkynes (52), aldehydes (qv) (53), ketones (qv) (54), isocyanates (55), and a2o compounds (56). They also react with diborane (43) and a variety of other Lewis acids. Alkyl haUdes react with primary and secondary arsiaes to yield quaternary arsenic compounds (57). 

Where X is Br or Q, the free acids may be obtained by acidification of the alkaline solution, but where X is I, the acids must be isolated as salts to avoid reduction of the arsonic acids by HI. Rather than using alkyl haUdes, alkyl or dialkyl sulfates or alkyl arenesulfonates can be used. Primary alkyl haUdes react rapidly and smoothly, secondary haUdes react only slowly, whereas tertiary haUdes do not give arsonic acids. AHyl haUdes undergo the Meyer reaction, but vinyl hahdes do not. Substituted alkyl haUdes can be used eg, ethylene chlorohydrin gives 2-hydroxyethylarsonic acid [65423-87-2], C2H2ASO4. Arsinic acids, R2AsO(OH), are also readily prepared by substituting an alkaU metal arsonite, RAs(OM)2, for sodium arsenite ... 

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... 

Arsine affects the ability of the blood system to carry oxygen by destroying red blood cells. The lack of oxygen rapidly affects all body tissues, especially the central nervous system. Arsine may also affect the kidneys, liver, and heart. Most deaths related to arsine exposure are believed to be secondary to acute renal failure. Arsine is carcinogenic. 

The synthesis of alkali metal organophosphides and arsenides is usually most conveniently achieved by the direct metalation of a primary or secondary phosphine/arsine with a strong deprotonating agent such as an alkyllithium or an alkali metal hydride ... 

Abstract This chapter principally concerns oxidations of organic substrates containing N, O, S, P, As and Sb. Oxidations of amines are covered first, including primary amines to nitriles or amides secondary amines to imines or other products tertiary amines to N-oxides or other prodncts (Section 5.1) and the oxidation of amides (5.2). Oxidation of ethers to esters or lactones follows (5.3), then of sulfides to sulfoxides or sulfones (5.4) and of phosphines, arsine and stibines to their oxides (5.5). A final section (5.6) concerns such miscellaneous oxidations not covered by other sections in the book. 

The As—N bond is labile and this has been widely exploited in synthetic arsenic chemistry. Some idea of the versatility168 can be seen from Schemes 1 and 2. Refluxing secondary amines with tris(dimethylamino)arsine effects transamination (equation 6). These tris(dialkyl-amino)arsines undergo the general reactions in Scheme 1, enabling ready access to a wide variety of compounds, many of them finding use as ligands in transition metal complexes (see Chapter 14 of this work). 

As mentioned in Chapter II, many metallic arsenides are found in Nature. Arsenic combines directly with most metals to form stable compounds, those of the heavy metals being the most stable. The latter may be obtained by allowing an aqueous solution of a salt of the appropriate metal to drop into an atmosphere of arsine, air being completely absent, and the vessel continually shaken.1 Precipitation by passing arsine into the salt solution is not satisfactory as, in the case of copper, silver, gold, mercury and lead, a secondary reaction with the excess of metallic ions occurs ... 

Reactions of secondary arsines with CS2 proceed in the same way as those of the corresponding phosphines. The phosphino- and arsino-dithioformates coordinate via one sulfur atom and the phosphorus or arsenic atom. H NMR, IR and UV-visible spectra show that the second sulfur atom of the CS2 fragment is exocyclic.101,102 Reaction of (92) with (93) gives hexacoordinated (94) with the evolution of 1 mol of CO.103... 

However, in the case of 32f, the elements of diethoxy methyl chloride are lost to give 4-methoxyarsabenzene 33 36). Alternatively, if 32f is reduced to secondary arsine 34, methanol is eliminated to give 35 37>. On hydrolysis, 35 affords 4-arsabenzaldehyde 36. Similarly 32g has been converted to 24g which on hydrolysis gave 4-arsabenzoic acid 37 38 39). 

Ammonium arsenates.—Excess of ammonia precipitates normal ammonium arsenate, (NH4)3As04, from concentrated solutions of the primary and secondary salts. It yields a very alkaline solution, decomposed by zinc and by aluminium with evolution of hydrogen and arsine.14 Secondary ammonium arsenate, (NH4)2HAs04, is gradually deposited from a concentrated solution of arsenic acid and ammonium hydroxide.15 Loss of ammonia, or addition of arsenic acid to its solution, converts it into primary ammonium arsenate, NH4H2As04, crystals of density 2-307 16 or 2-3105.17... 

Reduction of the dialkylchloroarsines with LiAlILt affords an alternative route to the secondary arsines, but... 

The organohaloarsines are very reactive species and are commonly used to prepare heteroleptic tertiary arsines (see Section 2), primary and secondary arsines (see Section 3), and aminoarsines and catenated arsines (see Section 7.3). They easily hydrolyze to their respective arsonous and arsinous acids (equation 27) and are oxidized in air to the corresponding arsonic and arsinic acids (equation 28). 

Relatively few organoarsenic compounds that contain an As-B bond are known. > > In most cases, these are synthesized by the straightforward reaction of the primary, secondary, and tertiary arsine with diborane or BH3 THF (equation 29). As-B bonding also results when the BH3 moiety reacts with Sn-As and As-P-As bonded compounds (equations 30 and 31). ... 

The tertiary arsines easily form adducts with the aluminum alkyls. The reaction of R2AICI (R = Me, i-Bu) with As[SiMc3]3 does not lead to a dehalosilylation reaction, but yields the adducts R2(Cl)AlAs[SiMe3]3. The other known As-Al bonded compounds are base-stabilized monomeric arsinoalanes and the cycloarsinoalanes. Although a few secondary arsines react with aluminum alkyls to give the cycloarsinoalanes (equations 34 and 35),6s,66,70 1 2-elimination route to arsinoalanes becomes... 

Relatively few germylarsines are known. They are usually prepared from the respective sUylarsine by a salt elimination or dehalosilylation reaction (equations 53-55). Cleavage of the Ge-N bond with a secondary arsine also leads to the formation of germylarsines (equation 56). Oxidation of the germylarsines with oxygen leads to the respective metal arsinates, R3Ge-0-As(0)R2. 

Effects of long-term exposure to low levels of arsine are not well documented however, most of the reported deaths are believed to be secondary to acute renal failure. Exposure to other arsenic compounds to which arsine is metabolized can induce lung, bladder, kidney, and skin cancer in humans (Kleinfeld, 1980 Lenza, 2006). 

Caution. Lithium diphenylarsenide and lithium diphenylphosphide are strong bases and very corrosive, and contact of them with the skin should be avoided. Hydrolysis of both compounds is vigorous and generates the malodorous and toxic secondary arsine or phosphine. Hence these experiments should be conducted in a fume hood. The products and the intermediates are also toxic and should be handled with due care. All manipulations should be done under nitrogen. 

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