Bart reaction

Arylarsonic acids are most readily prepared by the Bart Reaction, in which a diazonium salt in aqueous solution is run into a solution of sodium arsenite in an excess of sodium carbonate. The addition of copper sulphate to the +. ... 

The success of the Bart reaction when applied to nuclear- substituted anilines is often much affected by the pH of the reaction-mixture. Furthermore, the yields obtained from some m-substituted anilines, which under the normal conditions are usually low, arc considerably increased by the modifications introduced by Scheller, and by Doak, in which the diazotisation is carried out in ethanolic solution followed by reaction with arsenic trichloride in the presence of a cuprous chloride or bromide catalyst. 

The Bart reaction can be carried a stage further. For example, dichloro-phenylarsine, CjHjAsCl, when added to an excess of sodium carbonate solution, gives CjHjAsfONa) this solution, if similarly treated with benzenedia-zonium chloride, affords diphenylarsinic acid, (CjHjjjAsf. OjOH. 

The Bart reaction has now been extended to the synthesis of arylphosphonic acids by the interaction of the diazonium fluoroborate and phosphorus trichloride (Doak and Freedman, 1951). 

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 ... 

Acetoacetic ester condensation Amdt-Eistert reaction Bart reaction. ... 

Aiomatic aisonic acids aie generally prepared by tiie Bart reaction from an aromatic diazonium salt and 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 ... 

The Bart reaction shows characteristics similar to the Sandmeyer reaction (anionic reagent, catalysis by copper). However, it has not been investigated in the light of the modern concepts applied to the elucidation of the Sandmeyer reaction (Sec. 8.6). 

Bart reaction 275 Beech reaction 246 Benzenethioloxide ion 116f., 234, 271 Benzidine, see 4,4 -Diaminobiphenyl Benzo-S-dioxothiadiazole 184... 

Bart reaction (org chem( Formation of an aryl arsonic acid by treating the aryl diazo... 

Baeyer-Villiger reaction, 9, 3 43, 3 Bamford-Stevens reaction, 23, 3 Barbier Reaction, 58, 2 Bart reaction, 2, 10 Barton fragmentation reaction, 48, 2 Bechamp reaction, 2, 10 Beckmann rearrangement, 11, 1 35, 1 Benzils, reduction of, 4, 5 Benzoin condensation, 4, 5 Benzoquinones ... 

Bart Reaction Borsche (Cinnoline) Synthesis Demianov Rearranement Diazo Reaction Gattermann Reaction Gattermann Method Pschorr Arvlation Sandmever Reaction Schiemann Reaction (Bak-Schiemann JRxn) Tiffeneau-Demianov Reaction fVidman-Stoermer ([Pg.847]

Barbituric acid, 1001, 1002 Bart reaction, 597, 617, 618 Baths see Heating baths and Cooling baths... 

Three methods for the preparation of aromatic arsonic adds are de- scribed in this review. By far the most widely applicable of these is the Bart reaction, which involves the interaction of a diazonium salt with an inorganic arsenic compound. In the original Bart process 1 and most of its modifications an alkali arsenite is used, as shown in the following equation. 

Sodium carbonate is often employed as a buffering agent in the ordinary Bart reaction. In this way phenylarsonic acid has been prepared in yields ranging from 50-60% 7 to as high as 86% 8 as compared with yields of 40-50% by the original process. The yield from benzenediazonium chloride and sodium arsenite is greatly influenced by the concentration of the arsenite, the speed of reaction, and especially by the pH of the solution (which should remain constant). All compounds, like sodium carbonate, which play the role of buffer, tend to increase the yield.9... 

Scheller 17 modified the Bart reaction to such an extent that his method is often referred to as the Scheller reaction. Primary aromatic amines, dissolved in methanol or glacial acetic acid, are diazotized in the presence of arsenic trichloride and a trace of cuprous chloride. Removal of the solvent followed by treatment with water and sodium hydrosulfite gives the expected arsonic acids. 

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... 

A comparison of the yields of the meta and ortho isomers is significant. A survey of Bart reactions on variously substituted m- and o-nitroanilines further illustrates the hampering effect of m-nitro groups and the strong beneficial influence of o-nitro groups. Two examples are given below ... 

When o-iodoaniline is subjected to the Bart reaction two products result, o-phenylenediarsonic add in 20% yield, together with a lesser amount of o-iodophenylarsonic acid.29 The o-iodophenylarsonic acid first formed reacts with another molecule of sodium arsenite (Rosenmund reaction) to produce the diarsonic acid. The conversion of 2,4-, 2,5-, and 3,4-dichloroaniline to the corresponding arsonic adds takes place in yields of 60-70%.88... 

Hydroxyl Groups. Although o- and p-aminophenols have been converted into o- and p-hydroxyphenylarsonic adds in satisfactory yields (35-90%),u>84 the reaction fails with the meta isomer.26 Several substituted hydroxyphenylarsonic acids have been prepared by the Bart reaction. Following are a number of examples ... 

Arsono Groups. The three isomeric aminophenylarsonic acids can be converted into the corresponding phenylenediarsonic adds by means of the Bart reaction. The o-isomer gives a 44% yield of the diarsonic add,13 and a 14% yield of p-phenylenediarsonic acid is recorded.47. It is to be noted that the presence of the o-nitro group in 2-nitro-4-arsonoaniline increases the yield from 14% to 70-85%.34 48... 

Sulfo and Sulfamido Groups. It has been shown that sulfanilic acid can be converted into p-sulfophenylarsonic acid (25-45%).49 60 By the ordinary Bart reaction p-sulfamidophenylatsonic acid (25%) may be prepared,60 although a better yield (57%) is obtained by a modified Scheller reaction.18 Apparently, metanilic acid and naphthionic acid will not yield the corresponding arsonic adds.18 61 Although m-sulfamido-phenylarsonic add is not available by the usual procedure it can be prepared in a 58% yield by the method of Scheller.18... 

COMPOUNDS PREPARED BY THE BART REACTION" 435 Compounds Prepared by the Bart Reaction—Continued... 

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