Bart’s reaction

The most recent modification of Bart s reaction involves the use of aryldiazonium borofluorides in place of the customary diazonium chlorides. Because of their increased stability the diazonium borofluorides were observed to have less tendency to decompose or to form byproducts when allowed to react with sodium arsenite furthermore, the reactions could be carried out at room temperature. The modification appears to be particularly useful in the preparation of p-nitrophenylar-sonic acid, the yield being 79% as compared with 45% by the original method of Bart. When other diazonium borofluorides were used as starting materials the yields were sometimes lower than those reported by the usual Bart procedure, but more often they were as good or slightly... 

The thiol (SH) group is introduced by reaction with potassium ethyl xanthate followed by acid hydrolysis. The phenylsulfanyl (phenylthio, SPh) group results from reaction with benzenethiolate ion. Sodium disulfide, Na2S2, yields diaryl disulfides. The arsonic acid group is introduced using Bart s reaction, in which a diazonium salt is reacted with sodium arsenite in the presence of a Cu(II) salt (Scheme 8.23). 

Benzenesulphonyl - p - arsanilic acid, CgH6.SO2.NH.CeH4. AsO(OH)2.—This add may be obtained either from p-arsanilic add and benzene sulphonic chloride by the Schotten-Baumann reaction, or from benzenesulphonyl-p-aminophenylamine by Bart s reaction. The sodium salt goes under the name of Hectine and the mercury salt is Hectargyre. 

The nitrocarboxylarylarsinic acids may be prepared by four methods (1) By treating diazotised nitrocarboxyarylaroines with sodium arsenite (Bart s reaction). 

Acetophenone-p-arsinic acid, CH3.CO.C61T. AjsO(OH)2 (see also below), is obtaincil irom p-amino-acetophenone by diazotisation and treatment with sodium arscnite (Bart s reaction). Tlie acid is insoluble in water, but soluble in alkalis or glacial acetic acid. 

It is of interest in connection with these arsenic compounds to mention one which was extensively used by the Germans in the Great War. It was known as blue cross or sneeze gas it has the formula (C6H5)2AsCl and is diphenyl-chloroarsine. It was prepared in large quantities through the use of Bart s reaction, which has been mentioned above. 

Aniline was diazotized and condensed with sodium arsenite. The benzenearsonic acid, C6H6AsO(OH)2, so prepared was reduced by sulphur dioxide to a derivative of arsenious acid, C6H5.As(OH)2, and the sodium salt of the latter was again condensed by Bart s reaction with benzenediazonium chloride —... 

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). 

In retrospect, I was stunned by my failure to act appropriately in the moment. Bart of the reason was because I had lost sight of the fact that chemical reactions can be fatal, and because Carolyn s reaction was, for the most part, invisible. I also did not understand how dependent she was on her attendants in these kinds of situations. However, another major factor was that I d been exposed to the smell of fragrances, dryer sheets and cleaning products that morning in the bed and breakfast where I was staying. My exposure had been brief and I thought I was recovered, but in fact my thinking and reactions were still considerably dulled. This was a wake-up call. 

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

The preparation of phenylarsonic acid, which proceeds in an average yield of 45-55%, must of necessity serve as the basis for comparison of yields from substituted amines. The following discussion deals primarily with reactions taking place in neutral or alkaline solution practically all the yields reported in this discussion are by either the original Bart process or by Schmidt s modification, the few exceptions being noted. 

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

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. 

Figure 2. XC2H4 vs. p°H p ( ) andp°co2 ( ) for T=463 K, Wcat=0.5 g, Ftot=5 mmol s. being most pronounced at low steam partial pressures. Marecot et al. [21] found inhibition due to steam of propane and propene oxidation over Pt/y-Al203. Bart et al. [22] found inhibition of the propane oxidation over a three-way catalyst for reducing conditions and rate enhancement for oxidizing conditions. The inhibition by steam is in contrast to the oxidation of CO by O2 over the same catalyst, where steam was found to strongly enhance the reaction rate [15]. Carbon dioxide also inhibits the reaction rate, although the inhibition is much smaller.

Castellan, A., Bart, J. and Cavallaro, S. (1991). Nitric Acid Reaction of Cyclohexanol to Adipic Acid, Catal. Today, 9, pp. 255-283. 

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