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Balz–Schiemann reaction

December 14, 2023

The Balz–Schiemann reaction (also called the Schiemann reaction) is a chemical reaction in which a primary aromatic amine is transformed to an aryl fluoride via a diazonium tetrafluoroborate intermediate.[1][2][3] This reaction is a traditional route to fluorobenzene and some related derivatives,[4] including 4-fluorobenzoic acid.[5]

Balz-Schiemann reaction
Named after Günther Balz
Günther Schiemann
Reaction type Substitution reaction
Identifiers
Organic Chemistry Portal balz-schiemann-reaction
RSC ontology ID RXNO:0000127

The reaction is conceptually similar to the Sandmeyer reaction, which converts diazonium salts to other aryl halides (ArCl, ArBr).[6] However, while the Sandmeyer reaction involves a copper reagent/catalyst and radical intermediates,[7] the thermal decomposition of the diazonium tetrafluoroborate proceeds without a promoter and is believed to generate highly unstable aryl cations (Ar+), which abstract F− from BF4− to give the fluoroarene (ArF), along with boron trifluoride as the byproduct. Also Nitrogen is the by product.

Innovations edit

The traditional Balz–Schiemann reaction employs HBF4 and involves isolation of the diazonium salt. Both aspects can be profitably modified. Other counterions have been used in place of tetrafluoroborates, such as hexafluorophosphates (PF6−) and hexafluoroantimonates (SbF6−) with improved yields for some substrates.[8][9] The diazotization reaction can be effected with nitrosonium salts such as [NO]SbF6 without isolation of the diazonium intermediate.[2]

As a practical matter, the traditional Balz–Schiemann reaction consumes relatively expensive BF4- as a source of fluoride. An alternative methodology produces the fluoride salt of the diazonium compound. In this implementation, the diazotization is conducted with a solution of sodium nitrite in liquid hydrogen fluoride:[10]

ArNH2 + 2 HF + NaNO2 → [ArN2]F + NaF + 2 H2O
[ArN2]F → ArF + N2

History edit

The reaction is named after the German chemists Günther Schiemann [de] and Günther Balz.[1]

Additional literature edit

  • Roe A (1949). "Preparation of Aromatic Fluorine Compounds from Diazonium Fluoborates". Org. React. 5: 193. doi:10.1002/0471264180.or005.04. ISBN 0471264180.
  • Becker H. G. O., Israel G. (1978). "Ionenpaareffekte bei der Photolyse und Thermolyse von Aryldiazonium-tetrafluoroboraten". J. Prakt. Chem. 321 (4): 579–586. doi:10.1002/prac.19793210410.

References edit

  1. ^ a b Balz, Günther; Schiemann, Günther (1927). "Über aromatische Fluorverbindungen, I.: Ein neues Verfahren zu ihrer Darstellung" [Aromatic fluorine compounds. I. A new method for their preparation.]. Chemische Berichte (in German). 60 (5): 1186–1190. doi:10.1002/cber.19270600539.
  2. ^ a b Furuya, Takeru; Klein, Johannes E. M. N.; Ritter, Tobias (2010). "C–F Bond Formation for the Synthesis of Aryl Fluorides". Synthesis. 2010 (11): 1804–1821. doi:10.1055/s-0029-1218742. PMC 2953275. PMID 20953341.
  3. ^ Carey, Francis A.; Sundberg, Richard J. (2007). Advanced Organic Chemistry: Part B: Reactions and Synthesis (5th ed.). New York: Springer. p. 1031. ISBN 978-0387683546.
  4. ^ Flood, D. T. (1943). "Fluorobenzene". Organic Syntheses.; Collective Volume, vol. 2, p. 295
  5. ^ G. Schiemann; W. Winkelmüller (1943). "p-Fluorobenzoic Acid". Organic Syntheses.; Collective Volume, vol. 2, p. 299
  6. ^ Swain, C. G.; Rogers, R. J. (1975). "Mechanism of formation of aryl fluorides from arenediazonium fluoborates". J. Am. Chem. Soc. 97 (4): 799–800. doi:10.1021/ja00837a019.
  7. ^ Carey, Francis A.; Sundberg, Richard J. (2007). Advanced Organic Chemistry: Part B: Reactions and Synthesis (5th ed.). New York: Springer. p. 1030-1031. ISBN 978-0387683546.
  8. ^ Rutherford, Kenneth G.; Redmond, William; Rigamonti, James (1961). "The Use of Hexafluorophosphoric Acid in the Schiemann Reaction". The Journal of Organic Chemistry. 26 (12): 5149–5152. doi:10.1021/jo01070a089.
  9. ^ Sellers, C.; Suschitzky, H. (1968). "The use of arenediazonium hexafluoro-antimonates and -arsenates in the preparation of aryl fluorides". Journal of the Chemical Society C: Organic: 2317–2319. doi:10.1039/J39680002317.
  10. ^ Siegemund, Günter; Schwertfeger, Werner; Feiring, Andrew; Smart, Bruce; Behr, Fred; Vogel, Herward; McKusick, Blaine (2000). "Fluorine Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a11_349. ISBN 3527306730.

December 14, 2023
balz, schiemann, reaction, also, called, schiemann, reaction, chemical, reaction, which, primary, aromatic, amine, transformed, aryl, fluoride, diazonium, tetrafluoroborate, intermediate, this, reaction, traditional, route, fluorobenzene, some, related, deriva. The Balz Schiemann reaction also called the Schiemann reaction is a chemical reaction in which a primary aromatic amine is transformed to an aryl fluoride via a diazonium tetrafluoroborate intermediate 1 2 3 This reaction is a traditional route to fluorobenzene and some related derivatives 4 including 4 fluorobenzoic acid 5 Balz Schiemann reactionNamed after Gunther Balz Gunther SchiemannReaction type Substitution reactionIdentifiersOrganic Chemistry Portal balz schiemann reactionRSC ontology ID RXNO 0000127 The reaction is conceptually similar to the Sandmeyer reaction which converts diazonium salts to other aryl halides ArCl ArBr 6 However while the Sandmeyer reaction involves a copper reagent catalyst and radical intermediates 7 the thermal decomposition of the diazonium tetrafluoroborate proceeds without a promoter and is believed to generate highly unstable aryl cations Ar which abstract F from BF4 to give the fluoroarene ArF along with boron trifluoride as the byproduct Also Nitrogen is the by product Contents 1 Innovations 2 History 3 Additional literature 4 ReferencesInnovations editThe traditional Balz Schiemann reaction employs HBF4 and involves isolation of the diazonium salt Both aspects can be profitably modified Other counterions have been used in place of tetrafluoroborates such as hexafluorophosphates PF6 and hexafluoroantimonates SbF6 with improved yields for some substrates 8 9 The diazotization reaction can be effected with nitrosonium salts such as NO SbF6 without isolation of the diazonium intermediate 2 As a practical matter the traditional Balz Schiemann reaction consumes relatively expensive BF4 as a source of fluoride An alternative methodology produces the fluoride salt of the diazonium compound In this implementation the diazotization is conducted with a solution of sodium nitrite in liquid hydrogen fluoride 10 ArNH2 2 HF NaNO2 ArN2 F NaF 2 H2O ArN2 F ArF N2History editThe reaction is named after the German chemists Gunther Schiemann de and Gunther Balz 1 Additional literature editRoe A 1949 Preparation of Aromatic Fluorine Compounds from Diazonium Fluoborates Org React 5 193 doi 10 1002 0471264180 or005 04 ISBN 0471264180 Becker H G O Israel G 1978 Ionenpaareffekte bei der Photolyse und Thermolyse von Aryldiazonium tetrafluoroboraten J Prakt Chem 321 4 579 586 doi 10 1002 prac 19793210410 References edit a b Balz Gunther Schiemann Gunther 1927 Uber aromatische Fluorverbindungen I Ein neues Verfahren zu ihrer Darstellung Aromatic fluorine compounds I A new method for their preparation Chemische Berichte in German 60 5 1186 1190 doi 10 1002 cber 19270600539 a b Furuya Takeru Klein Johannes E M N Ritter Tobias 2010 C F Bond Formation for the Synthesis of Aryl Fluorides Synthesis 2010 11 1804 1821 doi 10 1055 s 0029 1218742 PMC 2953275 PMID 20953341 Carey Francis A Sundberg Richard J 2007 Advanced Organic Chemistry Part B Reactions and Synthesis 5th ed New York Springer p 1031 ISBN 978 0387683546 Flood D T 1943 Fluorobenzene Organic Syntheses Collective Volume vol 2 p 295 G Schiemann W Winkelmuller 1943 p Fluorobenzoic Acid Organic Syntheses Collective Volume vol 2 p 299 Swain C G Rogers R J 1975 Mechanism of formation of aryl fluorides from arenediazonium fluoborates J Am Chem Soc 97 4 799 800 doi 10 1021 ja00837a019 Carey Francis A Sundberg Richard J 2007 Advanced Organic Chemistry Part B Reactions and Synthesis 5th ed New York Springer p 1030 1031 ISBN 978 0387683546 Rutherford Kenneth G Redmond William Rigamonti James 1961 The Use of Hexafluorophosphoric Acid in the Schiemann Reaction The Journal of Organic Chemistry 26 12 5149 5152 doi 10 1021 jo01070a089 Sellers C Suschitzky H 1968 The use of arenediazonium hexafluoro antimonates and arsenates in the preparation of aryl fluorides Journal of the Chemical Society C Organic 2317 2319 doi 10 1039 J39680002317 Siegemund Gunter Schwertfeger Werner Feiring Andrew Smart Bruce Behr Fred Vogel Herward McKusick Blaine 2000 Fluorine Compounds Organic Ullmann s Encyclopedia of Industrial Chemistry doi 10 1002 14356007 a11 349 ISBN 3527306730 Retrieved from https en wikipedia org w index php title Balz Schiemann reaction amp oldid 1165637380, wikipedia, wiki, book, books, library,

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