Mercury salts reactions with aromatic compounds

WOLFFENSTEIN-BOTERS REACTION. Simultaneous oxidation and nitration of aromatic compounds to nitrophcnols with nitric acid or the higher oxides of nitrogen in the presence of a mercury salt as catalyst. Hydroxynitration of benzene yields picric acid. 

The preparation of organopalladium compounds by exchange reactions of palladium salts and organo-lead, -tin, or -mercury compounds is apparently not the only way that they can be obtained but it does seem to be the most useful way. Convincing evidence is now available to show that direct metalation of aromatic compounds with palladium salts (palladation) can occur. Since the initial report of Cope and Siekman 32> that palladium chloride reacted readily with azobenzene to form an isolable chelated, sigma-bonded arylpalladium compound, several additional chelated arylpalladium compounds have been prepared. 

It is rather important to note that if an aromatic nitro compound is the substance being nitrated, addition of mercuric nitrate to the nitric acid has no effect on the reaction. For example, nitrobenzene is nitrated to dinitrobezene in the same yield both in the presence of a mercury salt and in its absence. This can be explained by the fact that nitro compounds such as nitrobenzene do not yield addition product with mercuric salts. 

Arylmercuric salts can be obtained with extraordinary ease by mercuration of aromatic compounds with mercury salts, the reaction involving direct replacement of hydrogen by mercury ... 

The majority of aliphatic ketones give the secondary alcohol on reduction at electrodes of carbon, mercury, lead, or platinum. The usual choice of electrolyte has been dilute sulfuric acid, acetate buffer, or a neutral salt solution, which will become alkaline during the course of reaction that consumes protons. Relatively few studies have been recorded of the isomer ratio obtained by reduction of open chain ketones with a prochiral center adjacent to the carbonyl function [32,33]. Results are collected in Table 2, and one aromatic carbonyl compound is included here for convenience. In general, the erythro-alcohol is favored and in an excess over that present in the equilibrium mixture [32,33]. These results are explained in terms of adsorption of intermediates at the electrode surface. For many of the examples in Table 2, the total yield of alcohol is low and this result is not generally typical of aliphatic carbonyl compounds, as can be seen from Table 3. 

Schemes 9-3 and 9-4 are sequences of two substitutions, first a metallo-de-hydrogenation, followed by a halogeno-de-metallation. Scheme 9-3 is analogous to the well known electrophilic aromatic sulfonation of anthraquinone in position 1. This isomer is obtained only if the reaction is run in the presence of catalytic amounts of mercury (ii) salts. Nowadays, however, larger effort is devoted to either replace mercury by other catalysts, or in the search for processes leading to (practically) complete recovery of the mercury. This case raises two questions with respect to the reaction sequence (9-3) first, whether it is possible to apply a one-pot process with catalytic amounts of a mercury compound (not necessarily HgO) to the synthesis of compounds 9.5, and second, whether mercury can be completely recycled in processes using either stoichiometric or catalytic amounts of the element.

Substituted 3-alken-l-ynes can be hydroaminated with primary or secondary aliphatic or aromatic amines at the alkynyl sites or at the alkynyl and at the alkenyl sites in the presence of Hg(II) salts. However, the reaction is essentially stoichiometric in nature, even if the mercury compound can be recycled without apparent loss of activity [262-264]. 

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