BARTS

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). 

As(ONa), -I- CH,I — [CH,As(ONa)jI] CH,AsO(ONa), — CH,AsO(OH), unstable product losing sodium iodide to form disodium methylarsonate, which on acidification liberates methylarsonic acid. Note that this synthesis is limited to alkylarsonic acids, whereas the Bart synthesis (p. 312) is limited to aiy larsonic acids. 

To meet the needs of the advanced students, preparations have now been included to illustrate, for example, reduction by lithium aluminium hydride and by the Meerwein-Ponndorf-Verley method, oxidation by selenium dioxide and by periodate, the Michael, Hoesch, Leuckart and Doebner-Miller Reactions, the Knorr pyrrole and the Hantzsch collidine syntheses, various Free Radical reactions, the Pinacol-Pinacolone, Beckmann and Arbusov Rearrangements, and the Bart and the Meyer Reactions, together with many others. 

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. ... 

MnnualBook ofMSTM Standards, Bart 8—Nonferrous Metals, American Society for Testing and Materials, Philadelphia, Pa., 1981, pp. 164—165. 

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 ... 

BART SCHELLER Aromaticarsonylalion Aromatic arsonylaton substittuton of an aromatic amme by As via diazonum salts... 

Cu catalyzed arsonylation by substitution ol aromatic halides See also Bart-Schellet... 

In most cases, the product ratio can be controlled by choice of reaction conditions. Ketones are isolated under conditions where the tetrahedral intermediate is stable until hydrolyzed, whereas tertiary alcohols are formed when the/Tetrahedral intermediate decomposes while unreacted organometallic reagent remains. Bxamples of synthetic application of these reactions will be discussed in Chapter 7 of Bart B. 

Geiss, /. (she) goat doe. -bart, m., -barts-kraut, n. goatsbeard Spiraea aruncua). -blatt, n. honeysuckle (Lonicera). -bock, m. he-goat. 

B7. Barte, D. R., Bankoff, S. G., and Colahan, W. J., Summary of conference on bubble dynamics and boiling heat transfer held at the Jet Propulsion Laboratory, June 14th-15th, 1956, JPL Memo. No. 20-137, Calif. Inst. Tech., Pasadena. 

This reaction was discovered by Bart in 1911 (see also Bart, 1922 a, 1922 b). The yields are highly dependent on the alkalinity of the system. Bart s claim (1922b) that arylarsonic acid anions are formed directly from (Z)-diazoates is, however, doubtful (see below). Various modifications with increased yields are described in the review by Hamilton and Morgan (1944). The reaction can also be carried out with heteroaromatic diazonium salts (Capps and Hamilton, 1938). 

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). 

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