Bohn–Schmidt reaction

The reaction was first described in 1889 by René Bohn (1862–1922) and in 1891 by Robert Emanuel Schmidt (1864–1938), two German industrial chemists.

[2] The postulated reaction mechanism is explained below for the example of 2-hydroxyanthraquinone: The sulfuric acid protonates the keto group of the anthraquinone 1.

The sulfuric acid oxidizes the resulting hydroxyanthracenone 5, which is then protonated and the reaction starts all over again.

If boric acid is used, it has a regulating effect as ester formation occurs, which prevents further oxidation.

[1] The reaction is ideally suited for the general production of multi-hydroxyated anthraquinones due to the good atom economy.