Diazonium borofluorides

Difluorodiphenyl. Bis-diazotise a solution of 46 g. of benzidine (Section IV,88) in 150 ml. of concentrated hydrochloric acid and 150 ml. of water by means of a solution of 35 g. of sodium nitrite in 60 ml. of water add about 200 g. of crushed ice during the process (compare p-Fbtorotoluene above). Filter the solution and add it to a filtered solution of 85 g. of sodium borofluoride in 150 ml. of water. Stir for several minutes, collect the precipitated bis-diazonium borofluoride by suction filtration, wash with 5 ml. of ice-cold water, and dry at 90-100°. Place the dry salt in a flask fitted with an air condenser, immerse the flask in an oil bath, and slowly raise the temperature to 150° (Fume Cupboard ). When decomposition of the salt is complete, steam distil the mixture collect the 4 4 difluoro-diphenyl which passes over and recrystallise it from ethanol. The yield is 21 g., m.p. 92-93°. 

Claisen condensation, 6, 156 reactions, S, 92 IsothiazoIe-3-carboxyIic acids decarboxylation, 6, 156 Isothiazole-4-carboxylic acids decarboxylation, 6, 156 Isothiazole-5-carboxylic acids decarboxylation, S, 92 6, 156 IR spectroscopy, 6, 142 Isothiazole-3-diazonium borofluoride decomposition, 6, 158 IsothiazoIe-4-diazonium chloride, 3-methyl-reactions with thiourea, 6, 158 Isothiazole-5-diazonium chloride, 4-bromo-3-methyl-halogen exchange, 6, 163 Isothiazole-5-diazonium chloride, 3-methyl-reactions... 

The ice-cold fluoboric acid solution is added rather rapidly, with stirring, to the finished tetrazo solution, the temperature being kept below io°. A thick paste of 4,4 -biphenylene-bis-diazonium borofluoride forms. The mixture is stirred at io° for twenty to thirty minutes. It is then collected on a 19-cm. Buchner funnel, and washed consecutively with about 200 cc. of cold water, 200 cc. of cold commercial methyl alcohol, and 200 cc. of commercial ether the cake is sucked as dry as possible between washings. It is then dried in a vacuum desiccator over concentrated sulfuric acid (sp. gr. 1.84). The yield of the dry solid is 393 400 g. (68-69 Per cent of the theoretical amount). The product decomposes at 135-1370. 

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... 

Using a benzene-diazonium borofluoride pyridine molar ratio of 1 6. The reaction mixture is heterogeneous under these conditions. An intramolecular attack of the complexed pyridine nucleus may well be involved here. 

Homolytic substitution of pyridinium salts has scarcely been studied. The phenylation of pyridine in acetic acid solution by benzene-diazonium borofluoride has been reported,392 1 as has the phenylation of pyridine-metal complexes.3926... 

Diazonium borofluorides. A diazonium borofluoride can be reduced by adding solid NaBH4 in portions to a chilled methanolic solution or suspension of the salt. ... 

Diazomethyl phenyl ketone, 443 Diazonium borofluorides, 1052 Diazonium fluoroborates with nickel carbonyl, 722... 

Catalyzed Polymerizations of Acrylonitrile and of Methyl Methacrylate The results for methyl methacrylate are in parentheses. Each mixture contained in 5 ml. of solution a diazonium borofluoride equivalent to 10 mg. of CeHs.Na.BFi and either 0.2 ml. of acrylontrile or 0.05 ml. of methyl methacrylate. 

Diazonium borofluoride used Added salts Weight of polymer, g. Reaction time Per cent halogen in pol3rmer... 

Dinitrobenzene diazonium borofluoride Me2C=CHMe 3.27x10- MeCN... 

Thermal decomposition of diazonium borofluorides (G. Balz and G. Schlemann). This procedure is also applicable to aromatic fluorine compounds, particularly on the laboratory scale (e.g., p-fluorotoluene). 

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