Arsenic derivatives

Compounds with a Ln-As bond (Table Vn.2) have been obtained like the P-analogues via the interaction of LiAs(Bu-t)2 with REM trichlorides in THE medium [13] or via the hydride pathway [7]. The last method has been used for the synthesis of the bimetallic complex with diphenylarsino-bridges [14]. 

Crystalline arsenides of the Ln(AsR2)3 type are isolated in a high yield as associates with three THE molecules. One of them is readily split out at room temperature. The lutetium derivative under these conditions loses all coordinated THE to give the base-free complex Lu[As(Bu-t)2]3. When the synthesis of arsenides is carried out in the presence of TMED, the last mentioned substitutes THE in the isolated products. 

Cp2Lu(p.-AsPh2)2Li(TMED), 2.65 and 2.73 A, are somewhat different. The geometrical parameters of Cp2Lu bent sandwich in these molecules are close to each other the average Lu-C distance and Cp(centre)LuCp(centre) angle are 2.59 A and 131.9 for the As derivative and 2.602 A and 131.2 for the phosphor analog. 

Schumann H., Palamidis E., Schmid G., Boese R., Angew. Chem., Int. Ed. Engl, 25 (1986) 718. 

Trip2AlBr with LiP( l-Ad)SiPh3 gives the aluminium phosphide with Al-P bond of 234.2 pm and Si-P bond of 224.9 pm. (Me3Si)3P gives 1 1 complexes with AIX3 (X=C13r) with 

The stannaphosphene Trip2Sn=PMes adds a-ethylene aldehydes to give the 6 membered stannoxaphosphorinenes through [2+4] cycloaddition. Multinuclear NMR studies have been made on sterically crowded stannylamines, phosphines, sulphanes and allenes.  

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Both chloramine-T and dichloramine-T have marked antiseptic properties, chloramine-T being most frequently used because of its solubility in water. Aqueous solutions of chloramine-T can be used either for external application, or for internal application to the mouth, throat, etc, as chloramine-T in moderate quantities is non-toxic its aqueous solution can also be effectively used when the skin has come in contact with many of the vesicant liquid poison-gases, as the latter are frequently organic sulphur or arsenic derivatives which combine with or are oxidised by chloramine-T and are thus rendered harmless. 

Some 2-arylamino arsenic derivatives of thiazole have been also prepared (598) (Table 11-18). 

X 10 , and A3 = 3.0 x 10 . Hydrated arsenic acid loses water when heated at about 100°C with the formation of pyroarsenic acid [13453-15-1/, H4AS2O2. At higher temperatures additional water is lost to yield metaarsenic acid [10102-53-1/, HAsO. Arsenates derived from each of these acids are known. Treatment of a meta- or pyroarsenate with cold water gives the orthoarsenate. 

E. Reactions with Sulfui , Selenium, Tellurium, Phosphorus, and Arsenic Derivatives.. . 171... 

E. Reactions with Sulfur, Selenium, tellurium. Phosphorus, AND Arsenic Derivatives... 

The above syntheses constitute an extension of earlier work in which precursors of type (53, X = AsCH3 and PC6H5) were employed for the synthesis of a range of three-donor cyclic systems of general structure (55) (Kyba Chou, 1980). Yields for these reactions ranged from 19 to 40%. The arsenic derivatives of type (55) were the first macrocycles incorporating this heteroatom to be reported. 

The phosphorus chemical shift observed for the arsenic derivative 5 P = 315 is in accordance with the monomeric structure (39). This, however, is not the case for that observed for the antimony derivative, P = 44.5. The mass spectrum of the latter confirms its dimeric structure (37). 

The aqueous solution of arsenic pentoxide is arsenic acid which probably corresponds to the hemihydrate formula H3ASO4 O.5H2O. See Orthoarsenic acid. It behaves as a triprotic acid forming various arsenate derivatives of metals. 

FeAsS, realgar AS4S4, and orpiment AS2S3. The name arsenic derives from the Greek arsenicon, which in turn comes from the Persian azzarnikh, both terms referring to orpiment. 

Amine A-oxides, phosphine oxides and other phosphoryl compounds and analogous arsenic derivatives, and sulfoxides all give well-defined complexes with scandium. In many cases, authors deal with several of these classes of ligand in the same paper, so it will be most convenient to consider them together here. 

Anilino-553 and the three 3-tolylaminobenzo[6]thiophenes554 undergo the Bernthsen reaction when heated with an aliphatic carboxylic acid anhydride and zinc chloride 1o yield polycyclic compounds (e.g., 181 from 3-m-tolylaminobenzo[6]thiophene and acetic anhydride), They give analogous arsenic derivatives (e.g., 182 from 3-p-tolylaminobenzo[6]thiophene) when heated with arsenic trichloride in o-dichlorobenzene.553,554... 

Ylides of other elements have been used much less commonly than sulfur ylides in cyclopropanations. Rather, other ylides are better known for their uses in other types of reactions, the best example being the use of phosphonium ylides in the Wittig reaction with carbonyl compounds to give alkenes. Nonetheless, some cases of cyclopropanations have been reported with phosphonium ylides and the related arsenic derivatives. Examples are given in Table 9. 

Beer sometimes contains very small proportions of arsenic derived from the malt, sugars, hops, etc., used in brewing, and as the maximum amount allowable is one-hundredth of a grain of arsenic (As2Os) per gallon of the beer, it is advisable to keep a systematic check on the materials employed and also on the finished beer. 

Studies in rabbits, rats, mice, hamsters, and monkeys demonstrate that arsenic, administered orally or parenterally, as either As(III) or As(V), is rapidly distributed throughout the body. Many of these studies have used radiolabeled arsenic and it is noteworthy that arsenic-derived radioactivity is generally present in all examined tissues (Marafante, Bertolero and Edel, 1982 Kenyon, Del Razo and Hughes, 2005a Kenyon, Del Razo and Hughes, 2005b Lindgren, Vahter and Dencker, 1982 Vahter et al., 1982 Vahter and Marafante, 1985). 

The development of arsenic derivatives for medicinal purposes bridges inorganic and organic chemistry as well as older and modern pharmaceutical practices. Although these compounds do contain at least one arsenic atom (a metalloid), they are still considered to be organic molecules. The highly covalent carbon-arsenic bond makes these organometal-lic compounds stable and easy to isolate. 

There was only one report before 1970 on organogermanium arsenic derivatives. In 1966, Schumann and Blass484 prepared (Me3Ge)3As by the reaction of Me3GeNMe2 with AsH3 and described some of its properties. 

Friedheim EAH (1944) Trypanocidal and spirochetocidal arsenicals derived from s-triazine. J Am Chem Soc 66 1775-1778... 

It is well known that pentacovalent cyclic phosphorus compounds play an important role as intermediates in reactions involving nucleophilic attack on tetracoordinated phosphorus in biological systems. According to this background it appears to us that it is important to prepare the arsenic derivatives, which are more stable than the corresponding phosphorus compounds and allow the study of their conformation. 

Liebig s procedure 2 consists in heating the finely divided ore to redness with potassium hydrogen sulphate until fumes cease to be evolved. On cooling, the mass contains a soluble double sulphate of cobalt and potassium, which can be extracted with water, leaving a residue containing insoluble compounds, mainly oxides and arsenic derivatives of iron, nickel, and some cobalt.3... 

At laboratory scale a useful reagent for the preparation of arsenic derivatives is arsenic (III) chloride, AsCfr. A convenient synthetic method involves the reaction of AS2O3 with sulftnyl chloride (SOCI2) as shown in equation (3). ... 

In addition to the phosphorus ylide complexes, arsenic and snlfur yUde complexes of silver have been obtained, althongh no structural reports exist. While the arsenic derivatives match the phosphorus ylide complexes for stability of the Ag products, the sulfoxonium ylide complexes are somewhat less stable. 

A higher methanol content in the extraction mixture enhances the effectiveness of extraction of organic arsenic derivatives without altering the effectiveness of release of As(III) and As(V) salts, and arsenosugars [89]. The duration of the process can be reduced by ultrasound treatment or pressurized extraction [90]. Multiple extraction does not improve the efficiency of the process the quantity of arsenic remaining in the solid material depends solely on the volume of solvent retained in it (usually in the first cycle) and not on the number of repetitions of the leaching process [91]. 

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