The Bohn–Schmidt reaction, a named reaction in chemistry, introduces a hydroxy group at an anthraquinone system. The anthraquinone must already have at least one hydroxy group. 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.[1]
Bohn–Schmidt reaction ÜV5
René Bohn is one of the few industrial chemists after whom a reaction is named. In 1901, he made indanthrone from 2-aminoanthraquinone and thus laid the basis for a new group of dyes.[2]
The postulated reaction mechanism is explained below for the example of 2-hydroxyanthraquinone:
Bohn–Schmidt reaction mechanism
The sulfuric acid protonates the keto group of the anthraquinone1. This causes a shift of the electrons to the oxonium ion in molecule 2. This shift enables the sulfuric acid to attack the carbenium ion3 which is formed. The sulfuric acid oxidizes the resulting hydroxyanthracenone 5, which is then protonated and the reaction starts all over again. Finally, polyhydroxyanthraquinones with different numbers of hydroxy groups[1] are obtained. The reaction proceeds best at 25–50 °C[3] and takes up to several weeks to complete.[4]
The presence of a catalyst such as selenium or mercury accelerate the reaction.[1] By adding boric acid, sulfuric acid can be used instead of fuming sulfuric acid. If boric acid is used, it has a regulating effect as ester formation occurs, which prevents further oxidation.[1]
Atom economyedit
The reaction is ideally suited for the general production of multi-hydroxyated anthraquinones due to the good atom economy. Sulfuric acid can be reused, as it is split off at the very end. The reaction is therefore used in many dye production processes.[5] The only disadvantage is that in case boric acid is used, esterification occurs, which must then be reverted (hydrolyzed).
^ abcdZerong Wang (2009). Comprehensive Organic Name Reactions and Reagents. Hoboken, New Jersey: John Wiley & Sons. pp. 459–460. ISBN9780471704508.
^Remane, Horst; Girnus, Wolfgang (2012). "Meilensteine der Chemie 2012". Nachrichten aus der Chemie. 60: 11–21. doi:10.1002/nadc.201290036.
^Eckert, Alfred (1913). "Zur Kenntnis der Bohn-Schmidt'schen Reaktion in der Benzolreihe und über die Bestimmung des Stickstoffs nach Kjeldahl in Nitroverbindungen". Monatshefte für Chemie. 34 (10): 1957–1964. doi:10.1007/BF01518987. S2CID 95964582.
^Helmut Krauch, Werner Kunz (2009), Reaktionen der organischen Chemie (in German), John Wiley & Sons, p. 127, ISBN978-3-527-62512-3
^Phillips, Max. (1929). "The Chemistry of Anthraquinone". Chemical Reviews. 6: 157–174. doi:10.1021/cr60021a007..
January 01, 1970
bohn, schmidt, reaction, named, reaction, chemistry, introduces, hydroxy, group, anthraquinone, system, anthraquinone, must, already, have, least, hydroxy, group, reaction, first, described, 1889, rené, bohn, 1862, 1922, 1891, robert, emanuel, schmidt, 1864, 1. The Bohn Schmidt reaction a named reaction in chemistry introduces a hydroxy group at an anthraquinone system The anthraquinone must already have at least one hydroxy group The reaction was first described in 1889 by Rene Bohn 1862 1922 and in 1891 by Robert Emanuel Schmidt 1864 1938 two German industrial chemists 1 Bohn Schmidt reaction UV5 Rene Bohn is one of the few industrial chemists after whom a reaction is named In 1901 he made indanthrone from 2 aminoanthraquinone and thus laid the basis for a new group of dyes 2 Contents 1 Reaction mechanism 2 Atom economy 3 See also 4 ReferencesReaction mechanism editThe postulated reaction mechanism is explained below for the example of 2 hydroxyanthraquinone nbsp Bohn Schmidt reaction mechanism The sulfuric acid protonates the keto group of the anthraquinone 1 This causes a shift of the electrons to the oxonium ion in molecule 2 This shift enables the sulfuric acid to attack the carbenium ion 3 which is formed The sulfuric acid oxidizes the resulting hydroxyanthracenone 5 which is then protonated and the reaction starts all over again Finally polyhydroxyanthraquinones with different numbers of hydroxy groups 1 are obtained The reaction proceeds best at 25 50 C 3 and takes up to several weeks to complete 4 The presence of a catalyst such as selenium or mercury accelerate the reaction 1 By adding boric acid sulfuric acid can be used instead of fuming sulfuric acid If boric acid is used it has a regulating effect as ester formation occurs which prevents further oxidation 1 Atom economy editThe reaction is ideally suited for the general production of multi hydroxyated anthraquinones due to the good atom economy Sulfuric acid can be reused as it is split off at the very end The reaction is therefore used in many dye production processes 5 The only disadvantage is that in case boric acid is used esterification occurs which must then be reverted hydrolyzed See also editWolffenstein Boters reactionReferences edit a b c d Zerong Wang 2009 Comprehensive Organic Name Reactions and Reagents Hoboken New Jersey John Wiley amp Sons pp 459 460 ISBN 9780471704508 Remane Horst Girnus Wolfgang 2012 Meilensteine der Chemie 2012 Nachrichten aus der Chemie 60 11 21 doi 10 1002 nadc 201290036 Eckert Alfred 1913 Zur Kenntnis der Bohn Schmidt schen Reaktion in der Benzolreihe und uber die Bestimmung des Stickstoffs nach Kjeldahl in Nitroverbindungen Monatshefte fur Chemie 34 10 1957 1964 doi 10 1007 BF01518987 S2CID 95964582 Helmut Krauch Werner Kunz 2009 Reaktionen der organischen Chemie in German John Wiley amp Sons p 127 ISBN 978 3 527 62512 3 Phillips Max 1929 The Chemistry of Anthraquinone Chemical Reviews 6 157 174 doi 10 1021 cr60021a007 Retrieved from https en wikipedia org w index php title Bohn Schmidt reaction amp oldid 1097157166, wikipedia, wiki, book, books, library,
