Arsonic acids preparation

The conversion of an aromatic diazonium compound into the corresponding arsonic acid by treatment with sodium arsenite in the presence of a catalyst, such as copper or a copper salt, is called the Bart reaction. A modification of the reaction employs the more stable diazonium fluoborate in place of the diazonium chlorid.i. This is illustrated by the preparation of />-nitrophenylarsonic acid ... 

Good yields of phenylarsine [822-65-17, C H As, have been obtained by the reaction of phenylarsenic tetrachloride [29181-03-17, C H AsCl, or phenyldichloroarsine [696-28-6], C3H3ASCI25 with lithium aluminum hydride or lithium borohydride (41). Electrolytic reduction has also been used to convert arsonic acids to primary arsines (42). Another method for preparing primary arsines involves the reaction of arsine with calcium and subsequent addition of an alkyl haUde. Thus methylarsine [593-52-2], CH As, is obtained in 80% yield (43) ... 

A large number of polymeric substances, (RAs) or (ArAs), are also known (113). They are usually prepared by the reduction of arsonic acids with hypophosphorous acid (100,114) or sodium dithionite (115). Most of these polymers have not been well characterized. An insoluble, purple material, poly(methylarsinidene) [26403-94-1], (CH As), prepared by the interaction of methylarsine and a dihalomethylarsine, however, has been shown by an x-ray investigation to have a ladderlike polymeric stmcture in which the inter-mng distances correspond to one-electron bonds (116) ... 

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 ... 

More extensive catenation occurs in the cyc/o-polyarsanes (RAs) which can readily be prepared from organoarsenic dihalides or from arsonic acids as follows ... 

Arsonic acids RAsO(OH)2 are amongst the most important organoarsonium compounds. Alkyl arsonic acids are generally prepared by the Meyer reaction in which an alkaline solution of AS2O3 is heated with an alkyl halide ... 

In general, primary aromatic amines can be converted into the corresponding arsonic acids by the Bart reaction or by one of its modifications. This method has been used to prepare arsonic acids of the benzene, naphthalene, fluorene, and anthraquinone series as well as of a number... 

It was not until thirty-eight years later that this method of synthesis was applied to the aromatic series. Rosenmund,8 in 1921, prepared phenyl-arsonic acid (in low yield) and o-carboxyphenylarsonic acid (44% yield) from tripotassium arsenite and bromobenzene and o-bromobenzoic acid, respectively. Since that time only one other arsonic acid, o-phenylene-diarsonic acid,29 82 has been obtained in good yields by Rosenmund s method. From two other aromatic bromides, p-bromobenzoic add and... 

Lewisite 1 per se is never found in the environment. Figure 18 shows that this compound hydrolyzes rapidly on contact with moisture to 2-chlorovinyl arsonous acid, which in turn slowly dehydrates to lewisite oxide (syn. 2-chlorovinyl arsenous oxide) (16). Both 2-chlorovinyl arsonous acid and lewisite oxide are nonvolatile. The most frequently used method for the identification of CWC-related chemicals is based on gas chromatography (GC) in combination with mass spectrometry (GC/MS). Indirect GC/MS analysis of lewisite 1 requires sample preparation, which involves conversion of lewisite oxide to 2-chlorovinyl arsonous acid in an acidic environment, followed by derivatization (12). The obtained species is both volatile and thermally stable, and thus amenable to GC analysis. Often, a mercaptan reagent is used as a derivatization agent. The reaction with 3,4-dimercaptotoluene is shown in Figure 19. 

The very stable spirocyclic compounds of types XXII and XXIII have been known for a long time (10,54, 60,161). These have been prepared by allowing 1 mol of the appropriate arsonic acid to react with 2 mol of the 1,2-dihydroxy compound, the water formed being removed either by performing the reaction in acetic anhydride or by azeotropic distillation from a suitable solvent, e.g., benzene (161). 

After preparing the o-nitrophenylarsomc acid (p 29) this modification may be tried instead of, or in addition to, the above preparation. In the case of arsonic acids the method is of particular utility in that it results only in the reduction of the mtro group, while stronger reducing agents reduce the arsonic acid group as well. 

When the reduction of a nitrophenylarsonic acid is in question the state of affairs is still more complicated, for it becomes possible to reduce either the mtro- or the arsonic-acid group without affecting the other, or to reduce both simultaneously. For example, ferrous sulfate and alkali give aminophenylarsonic adds, while sulfur dioxide and hydriodic acid together permit the preparation of certain nitrophenylarsmoxides. Sodium hyposulfite (hydrosulfite) in excess, on the other hand, reduces the nitro- to the amino- group, with simultaneous formation of arseno compounds. Ims reagent was used... 

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. 

Arsonic acids have been prepared from readily available compounds such as arsenic(III) oxide and arsenic trichloride. Reaction of sodium arsenite with alkyl halides has been named the Meyer reaction, and reaction with arenediazonium salts the Bart reaction. In addition, some modifications have been made for the preparation of arsonic acids. Some examples are shown in equations 326 and 327. ... 

Arsinic acids have been prepared by similar methods as for the preparation of arsonic acids. Thus, reaction of sodium organoarsenites with alkyl halides (Meyer reaction) and reaction of sodium organoarsenite with arenediazonium salts (Bart reaction) are available for the preparation of arsinic acids. Several examples are shown in equations 333 and 334. ... 

Three methods for the preparation of aromatic arsonic acids are described in this review. By far the most widely applicable of these is the Bart reaction, which involves the interaction of a diazonium salt witB an inorganic arsenic compound. In the original Bart process and most of its modifications an alkali arsenite is used, as shown in the following equation. 

Sulfo and Sulfamido Groups. It has been shown that sulfanilic acid can be converted into p-sulfophenylarsonic acid (25-45%). By the ordinary Bart reaction p-sulfamidophenylatsonic acid (25%) may be prepared, although a better yield (57%) is obtained by a modified Scheller reaction. Apparently, metanilic acid and naphthionic acid will not yield the correspQnding arsonic acids. Although w-sulfamido-phenylarsonic acid is not available by the usual procedure it can be prepared in a 58% yield by the method of Scheller. ... 

Meyer, in 1883, developed a very interesting and useful method of preparing aliphatic arsonic acids from alkyl halides and. trisodium Sil 86111 0... 

The pyrolysis of organoarsenic compounds containing the arsenyl moiety has some limited preparative applications [arsenyl (As=0) by analogy with phosphoryl (P=0)]. The compounds are based on the arsonic acid RAs(0)(0H)2, the arsinic acid R2As(0)0H and the arsine oxide R3As=0 structures. The acids are in interesting contrast with the phosphorus series. The phosphonic and phosphinic esters are prepared from the phosphorus(III) precursors via the Arbuzov synthesis. This synthetic route fails with the arsenic analogues, and further, if an alkyl halide or a salt is added in the pyrolysis of arsonic or arsinic acid esters a retro-Arbuzov reaction takes place . ... 

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