Arsinic acids preparation

Hydroxy-8-methyl-1 4-benzisoxazine-6-arsinic acid, prepared by the chloraeetylation in alkaline solution of 8-amino-4-hydroxy-5-methylpheuylarsinic acid, crystallises from water in white prisms, soluble in alk is. 

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) ... 

Diarsines and Diarsenes. Under certain conditions, the reduction of compounds with two organic groups attached to arsenic may give rise to tetraalkyl-or tetraaryldiarsines. Thus a number of diarsines have been obtained by the reduction of arsinic acids with phosphorous or hypophosphorous acid (100). Diarsines can also be prepared by the treatment of a metal dialkyl- or diarylarsenide with iodine (101) or a 1,2-dihaloethane (102). 

Arsonic and Arsinic Acids. The arsonic acids, compounds of the type RAsO(OH)2, are among the most important organic arsenicals. The ahphatic arsonic acids are generally prepared by the Meyer reaction ie, heating an alkyl haUde with As O in alkaline solution ... 

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 ... 

A number of substituted phenylarsonic acids have been prepared by means of the Bart reaction (121). For the preparation of arsinic acids a sodium arylarsonite is used, and mixed diaryl or alkylarylarsinic acids can be prepared ... 

The Bart reaction is successful with a wide variety of aromatic and heterocycHc amines. A variation in which an aromatic amine, in the presence of arsenic trichloride, is dia2oti2ed in an organic solvent (the ScheUer reaction) has also found wide appHcation. Both arsonic and arsinic acids can be prepared by the ScheUer reaction which often gives better yields than the Bart reaction with electron-attracting substituents on the aromatic ring. For the commercial preparation of 4-aminophenylarsonic acid [98-50-0] (arsaniUc acid), C HgAsNO, and 4-hydroxyphenylarsonic acid [98-14-6] C H AsO, the Bnchamp reaction is used ... 

A number of esters of arsonic and arsinic acids have been prepared. One method involves the oxidation of dialkyl alkylarsonites with selenium dioxide ... 

Arsinic acids and arsine oxides may be prepared by extensions of the t Bart synthesis. Thus, diphenylardnic acid is obtained from benzene- diazonium chloride and disodium phenylarsenite. 

In addition to ortho isomers, as by-products in the Bechamp reactions, small amounts of arsinic acids are produced. As the reaction temperature rises the proportion of arsinic acids increases until at 220-230° they are the principal products. At higher temperatures oxidation brings about a decrease in yield. 4,4 -Diaminodiphenylarsinic acid has been prepared in a 20-30% yield by the interaction of aniline with arsenic acid at 230°.76... 

The Preparation op Aromatic Arsonic and Arsinic Acids by the Bart, Bechamp, and Rosenmund Reactions—Cliff S. Hamilton and Jack F. Morgan 415... 

The haloarsines are most commonly prepared from the reduction of the arsonic or arsinic acids by sulfur dioxide... 

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). 

These As-O bonded species are related by the fact that they contain arsenic in the -1-5 oxidation state. The arsonic acids, RAsO(OH)2, have one organo substituent bonded to the arsenic, while the arsinic acids, R2As(0)0H, have two. The most common preparative methods involve isolating the sodium or potassium salt. 

Arsine is prepared by treatment of Mg or Zn arsenides with aqueous acid ... 

This derivative is prepared by the electroljrtic reduction of the corresponding arsinic acid. It is a yhite, crystalline powder, M.pt. 155° to 160° C. with palladium dichloride it forms a black co-ordinaMon compound. ... 

Amino -5-acetamido-4 - hydroxy phenyldi -iodoarsine hy drl -odide may be prepared either from the arsenoxide, or by reduction of the arsinic acid with sulphurous add, using either an addified solution... 

It has already been stated that Bart used catalysts in his reaction, in order to eliminate the diaze-nitrogen at low temperatures and thus decrease the formation of by-products. In Schmidt s method, in addition to non-arseuated aromatic derivatives, arsenated derivatives may also occur as by-products. In the case of the preparation of phenyl-arsinic acid, the by-product is diphenylyl-4-arsinic acid, CgH4.Ph. AsO(OH)2, and the presence of such a derivative can only be accounted for on the assumption that one of the hydrogen atoms of tire benzene nucleus becomes labile at the moment when the replacement of the diazo-group by the arsinic acid grouping takes place. 

The method adopted in the preparation of this type of compound is to tetrazotise benzidine, couple one diazonium group with a component which can be reduced to give an amino-group (e.g. H-acid), and replace the second diazonium group by the arsinic acid radical. The acid gives a white hydroehloride and a white, crystalline acetyl derivative. 

This acid (I) is prepared from 4-nitro-5-chlorotolyl-2-arsinic acid by heating with sodium hypochlorite and ION sodium hydroxide solution. It is a white, crystalline powder, sparingly soluble in hot water. 

The N-acyl and N-alkyl derivatives of aminoarylarsinic acids are prepared by the usual methods. Acetyl-jp-aminophenylarsinic acid, in addition to the usual method of acetylation of the arsinic acid, may be formed by subjecting p-aminoacetanilide to the Bart-Schmidt reaction. An interesting series of N-aryl derivatives of p-aminophenylarsinic acid has been obtained by King and his co-workers in the course of seeking organic arsenicals of therapeutic value. ... 

This acid has a special interest for two reasons firstly, it was the first aromatic arsenical to be produced, although it was not recognised as such at the time secondly, its so um salt, Atoxyl, has proved of great value in medicine. Consequently, many attempts have been made to prepare this arsinic acid, but none seem to have been very successful as far as the yield is concerned. The following preparation is that due to Cheetham and Schmidt ... 

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