Baudisch

The name cupferron was assigned to the compound by O. Baudisch, and is derived from the fact that the reagent precipitates both copper and iron. Cupferron precipitates iron completely in strong mineral-acid solution, and copper is only quantitatively precipitated in faintly acid solution. The selectivity of the reagent is greatest in strongly acid solution. 

Bamberger s arguments were based mainly on classical organic chemistry, e.g., formation of derivatives, whereas Hantzsch was already using physicochemical methods. It took Bamberger 18 years to abandon his negative attitude towards the diazoate stereoisomerism (Bamberger and Baudisch, 1912). 

Bamberger s main achievements were the rediscovery of Blomstrand s diazonium formula and the development of a large number of methods for the preparation of diazoates and azo compounds. In the end, Bamberger abandoned his negative attitude towards the stereoisomerism of the diazoates by reason of his own experiments, which demonstrated the similarities in the oxidation behavior of isomeric series of oximes and diazo compounds (Bamberger and Baudisch, 1912). 

In 1925, Welo and Baudisch found that magnetite formed upon bringing a solution with Fe /Fe - 2, i.e. the ratio of magnetite, up to pH 9-10. Misawa et al. 

Welo, L.A. Baudisch, O. (1925) The two-stage transformation of magnetite into hematite. Phil. Mag. 50 399-408 Wen, L. Melendres, C.A. (1998) On the mechanism of hematite disposition on a metal surface under boiling conditions. Colloids Surfaces A 132 315-319 West, J.M. (1980) Basic corrosion and oxidation. Ellis Horwood, Chichester, 247 pp. 

An interesting reaction, the Baudisch reaction, involves the formation of nitrosophenols by the action of hydroxylamine hydrochloride and hydrogen peroxide, in the presence of metallic ions or certain Werner complexes, on aromatic compounds. The products are primarily o-nitrosophenol complexes of the metallic ion. Unfortunately, this reaction requires further development before it can be considered a reliable preparative procedure. 

The Baudisch reaction permits conversion of aromatic hydrocarbons to nitrosophenols. 

An intriguing method for preparing phenolic nitroso compounds was discovered by Baudisch [95]. Interestingly enough, the product mixture from the reaction appears to be primarily the ortho-substituted phenol, a class of compounds of which very few examples seem to have been described. 

Soon after the introduction of dimethylglyoxime as a specific reagent for nickel by Tschugaeff-Kraut-Brunck (1905-1907), Baudisch discovered a compound which precipitates copper and iron quantitatively from acid solutions.82 He appropriately named this reagent as cupferron . It is the water soluble ammonium salt of nitrosophenylhydroxylamine (5). When dissolved in chloroform, the whitish-grey copper compound gives a bright yellow solution and the brown yellow iron(III) compound a deep red solution. This behaviour reveals the inner complex character of these derivatives (6). 

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