Bart reaction procedures

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... 

Phenothiarsines (69) can be prepared by the same procedure. 2-Nitro-diphenylthioether is reduced to the amine (67). The arsonic acid (68), obtained by a Bart reaction, is transformed into the dichloroarsine and cyclized to (69) at 200°C (Scheme 12) <26JCS1207>. 

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... 

An important modification of the original Bart procedure was made by Scheller who diazotized primary amines, dissolved in alcohol or glacial acetic acid, in the presence of arsenic trichloride and found that better yields of arsonic acids could sometimes be obtained, particularly if the amine carried negative substituents in the meta position. The method has been slightly modified 140). The Scheller reaction has recently been used to prepare arsonic acids of 3-nitro-4-fluorobenzene and 2,5-dimethylpyridine 141, 142), and to prepare a number of arsinic acids such as (CeHs)[4,3-CH3(N02)C6H3]As02H by the reaction 143)... 

---