Baudisch reaction

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The Baudisch reaction is a name reaction in organic chemistry , which was first published in 1939 by Oskar Baudisch (1881–1950) and named after him. In 1947, the reaction was further developed by his colleague Georg Cronheim. The Baudisch reaction enables the synthesis of ortho -nitrosophenol.

Overview reaction

The synthesis of ortho -nitrosophenol takes place in several reaction steps starting from benzene , hydroxylamine and hydrogen peroxide in the presence of copper salts. The copper salt is necessary so that the nitrosyl compound is stabilized by the formation of a copper complex and further oxidation is prevented.

Overview reaction of the Baudisch reaction

Reaction mechanism

Several proposals for a reaction mechanism, some contradicting one another, can be found in the literature.

Oskar Baudisch reaction mechanism

First a nitroso group and then a hydroxyl group is added to a benzene molecule by oxidation.

Reaction mechanism according to Jan Konecny

In 1955 Konecny ​​described a mechanism in which the hydroxyl group is added first in a radical mechanism and then the nitroso group. The hydroxyl group comes from a hydrogen peroxide molecule and the nitroso group from nitrous acid .

Reaction mechanism according to Kazuhiro Maruyama

In 1967, Maruyama discovered alleged flaws in Konecny's reaction mechanism. Since he observed low yields when carrying out the Baudisch reaction with nitrous acid, he noted that nitrosation of a phenol with nitrous acid was impossible.

Zerong Wang reaction mechanism

In the reaction mechanism proposed by Zerong Wang, nitrosyl hydrogen ( 3 ) is initially formed from hydroxylamine ( 1 ) and hydrogen peroxide ( 2 ):

The nitrogen atom of the nitrosyl hydrogen now attacks the benzene ( 4 ), whereupon this forms a bond with the hydrogen peroxide. Intermediate stage 5 is formed by splitting off water . After the reaction with a copper (II) ion, the complex 6 is formed . The desired product 7 is then formed by an oxidation reaction with rearomatization .

Mechanism of the Baudisch reaction part 2

modification

Instead of the copper salt, other metal salts can also be used.

In the Baudisch reaction, however, no aromatic aldehydes or primary amines may be used, since the aldehyde group would react with the nitrosyl radical or the hydroxylamine. A primary amine would also react with the nitrosyl residue.

application

The Baudisch reaction was used to produce ortho -nitrosophenols.

Individual evidence

  1. ↑ a b Georg Cronheim: o-NITROSOPHENOLS. I. THE TYPICAL PROPERTIES OF o-NITROSOPHENOL AND ITS INNER COMPLEX METAL SALTS . In: The Journal of Organic Chemistry . tape 12 , no. 1 , January 1947, p. 1-6 , doi : 10.1021 / jo01165a001 .
  2. ^ Oskar Baudisch: Simple formation of o-nitrosophenol from benzene and hydroxylamine by air oxidation. Preparative representation of o-nitrosophenol and nitrosocresol from benzene or toluene by H2O2 oxidation . In: The natural sciences . tape 27 , no. 46 , November 1939, p. 768-769 , doi : 10.1007 / BF01498121 .
  3. ↑ a b c d e Wang, Zerong (Daniel Zerong): Comprehensive organic name reactions and reagents . John Wiley, Hoboken, NJ 2009, ISBN 978-0-471-70450-8 , pp. 263-266 .
  4. ↑ a b O. Baudisch: A NEW CHEMICAL REACTION WITH THE NITROSYL RADICAL NOH . In: Science . tape 92 , no. 2389 , October 11, 1940, p. 336-337 , doi : 10.1126 / science.92.2389.336 .
  5. ^ A b Jan O. Konecny: Hydroxylation of Benzene in Aqueous Solution in the Presence of Hydroxylamine Hydrochloride . In: Journal of the American Chemical Society . tape 77 , no. November 21 , 1955, p. 5748-5750 , doi : 10.1021 / ja01626a093 .
  6. ↑ Kazuhiro Maruyama, Iwao Tanimoto, Ryozo Goto: Studies on the Baudisch reaction. I. The synthesis of o-nitrosophenols . In: The Journal of Organic Chemistry . tape 32 , no. 8 , August 1967, p. 2516-2520 , doi : 10.1021 / jo01283a033 .