Wurtz–Fittig reaction
{{Short description|Chemical reaction}}
{{Use dmy dates|date=November 2023}}
{{Reactionbox
|Name = Wurtz–Fittig reaction
|Type = Coupling reaction
|NamedAfter = Charles Adolphe Wurtz
Wilhelm Rudolph Fittig
|Section3 = {{Reactionbox Identifiers
|OrganicChemistryNamed = wurtz-fittig-reaction
}}
}}
The Wurtz–Fittig reaction is the chemical reaction of an aryl halide, alkyl halides, and sodium metal to give substituted aromatic compounds.{{cite book |chapter= Wurtz–Fittig Reaction |first1= Zerong |last1= Wang |isbn= 9780470638859 |doi= 10.1002/9780470638859.conrr686 |year= 2010 |title= Comprehensive Organic Name Reactions and Reagents |volume= 686 |pages= 3100–3104}} Following the work of Charles Adolphe Wurtz on the sodium-induced coupling of alkyl halides (the Wurtz reaction), Wilhelm Rudolph Fittig extended the approach to the coupling of an alkyl halide with an aryl halide.{{cite journal
| title = Ueber die Synthese der Kohlenwasserstoffe der Benzolreihe | language = German | trans-title = On the synthesis of the hydrocarbons of the benzene series | first1 = Bernhard | last1 = Tollens | authorlink1 = Bernhard Tollens | author2 = Rudolph Fittig | journal = Justus Liebigs Annalen der Chemie | volume = 131 | issue = 3| pages = 303–323| year = 1864 | doi = 10.1002/jlac.18641310307| url = https://zenodo.org/record/1427231}}{{cite journal | title = Ueber das Aethyl- und Diäthylbenzol | language = German | trans-title = About ethyl- and diethylbenzene | first1 = Rudolph | last1 = Fittig | authorlink1 = Rudolph Fittig | first2 = Joseph | last2 = König | journal = Justus Liebigs Annalen der Chemie | volume = 144 | issue = 3 | pages = 277–294 | year = 1867 | doi = 10.1002/jlac.18671440308| url = https://zenodo.org/record/1427273}} This modification of the Wurtz reaction is considered a separate process and is named for both scientists.
:Image:Wurtz–Fittig synthesis.svg
The reaction works best for forming asymmetrical products if the halide reactants are somehow separate in their relative chemical reactivities. One way to accomplish this is to form the reactants with halogens of different periods. Typically the alkyl halide is made more reactive than the aryl halide, increasing the probability that the alkyl halide will form the organosodium bond first and thus act more effectively as a nucleophile toward the aryl halide.{{cite book |last=Desai |first=K. R. |title=Organic Name Reactions|url=https://archive.org/details/handbookinorgani00desa |url-access=limited |year=2008 |publisher=Oxford Book Company |location=Jaipur, India |isbn=9788189473327 |page=https://archive.org/details/handbookinorgani00desa/page/n267 259]}}
Typically the reaction is used for the alkylation of aryl halides. With the use of ultrasound sodium reacts with some aryl halides to produce biphenyl compounds.{{cite book |last1=Laue |first1=Thomas |last2=Plagens |first2=Andreas |title=Named Organic Reactions|url=https://archive.org/details/namedorganicreac00laue_814 |url-access=limited |edition=2nd|year=2005 |publisher=John Wiley & Sons |location=Wolfsburg, Germany|isbn=9780470010402 |page=[https://archive.org/details/namedorganicreac00laue_814/page/n312 305]}}
Mechanism
The mechanism of the Wurtz–Fittig reaction has not been the subject of modern investigations. The process was once proposed to involve the combination of an alkyl and aryl radicals.{{Cite journal |last1=Wooster |first1=Charles Bushnell |year=1932 |title=Organo-alkali Compounds |journal=Chemical Reviews |volume=11 |issue=1 |pages=1–91 |doi=10.1021/cr60038a001 |issn=0009-2665}}{{Cite journal |last1=Gilman |first1=Henry |last2=Wright |first2=George F. |year=1933 |title=The Mechanism of the Wurtz—Fittig Reaction. The Direct Preparation of an Organosodium (Potassium) Compound from an RX Compound |journal=Journal of the American Chemical Society |volume=55 |issue=7 |pages=2893–2896 |doi=10.1021/ja01334a044 |issn=0002-7863}} Another mechanistic proposal invoked the generation of organosodium intermediates.{{Cite journal |last1=Bachmann |first1=W. E. |last2=Clarke |first2=H. T. |year=1927 |title=The Mechanism of the Wurtz–Fittig Reaction |journal=Journal of the American Chemical Society |volume=49 |issue=8 |pages=2089–2098 |doi=10.1021/ja01407a038 |issn=0002-7863}} The reaction of sodium and chlorobenzene produces triphenylene, which supports a role for radicals. A role for organosodium compounds is supported by indirect evidence. For example, addition of carbon dioxide to a mixture of sodium and isobutyl bromide results in the formation of 3-methylbutanoic acid after acid workup.
{{cite journal |doi=10.1002/cber.190804102208 |title=Synthesen mittels Natrium und Halogenalkylen |date=1908 |last1=Schorigin |first1=Paul |journal=Berichte der Deutschen Chemischen Gesellschaft |volume=41 |issue=2 |pages=2711–2717 |url=https://zenodo.org/record/1426291 }}{{cite journal |doi=10.1002/cber.191004302128 |title=Über die Natriumalkyle und über ihre Reaktion mit den Äthern |date=1910 |last1=Schorigin |first1=Paul |journal=Berichte der Deutschen Chemischen Gesellschaft |volume=43 |issue=2 |pages=1931–1938 |url=https://zenodo.org/record/1794645 }}
Use of other metals
The Wurtz–Fittig reaction can be conducted using metals other than sodium. Some examples include potassium, iron, copper, and lithium.{{Cite book |title=March's advanced organic chemistry: Reactions, mechanisms, and structure.|last1=Smith |first1=Michael |year=2007 |publisher=Wiley-Interscience |last2=March |first2=Jerry |authorlink2=Jerry March |isbn=978-0471720911 |edition=6th |location=Hoboken, N.J. |oclc=69020965}} When lithium is used, the reaction occurs with appreciable yield only under ultrasound.{{Cite journal |year=1981 |title=Organic sonochemistry. Ultrasound-promoted coupling of organic halides in the presence of lithium wire |first1=Byung Hee |last1=Han |first2=Philip |last2=Boudjouk |journal=Tetrahedron Letters |volume=22 |issue=29 |pages=2757–2758 |doi=10.1016/S0040-4039(01)90544-1 |issn=0040-4039}} Ultrasound is known to cleave halogen atoms from aryl and alkyl halides through a free-radical mechanism{{Cite journal |year=1965 |title=Sonocleavage of halogens from aliphatic chains and aromatic rings |first1=S. |last1=Prakash |first2=J. D. |last2=Pandey |journal=Tetrahedron |volume=21 |issue=4 |pages=903–908 |doi=10.1016/0040-4020(65)80026-6 |issn=0040-4020}}
Applications
The Wurtz–Fittig reaction has limited applicability, because it is plagued by side reactions including rearrangements and eliminations. The reaction has been applied to the laboratory synthesis of some organosilicon compounds.{{Cite journal |title=The use of the Wurtz–Fittig reaction in the preparation of organo-substituted silanes |last1=Bassett |first1=E. A. |last2=Emblem |first2=H. G. |last3=Frankel |first3=M. |last4=Ridge |first4=D. |year=1948 |journal=Journal of the Society of Chemical Industry |volume=67 |issue=5 |pages=177–179 |doi=10.1002/jctb.5000670503 |issn=0368-4075}} One example is the conversion of tetraethyl orthosilicate to the mono-tert-butoxy derivative in 40% yield as summarized in this idealized equation:{{Cite journal |last1=Chappelow |first1=C. C. |last2=Elliott |first2=R. L. |last3=Goodwin |first3=J. T. |year=1962 |title=Synthesis of t-Butylsilicon Compounds by the Wurtz–Fitting Reaction |journal=The Journal of Organic Chemistry |volume=27 |issue=4 |pages=1409–1414 |doi=10.1021/jo01051a069 |issn=0022-3263}}
:{{chem2|Si(OC2H5)4 + 2 Na + (CH3)3CCl -> Si(OC2H5)3OC(CH3)3 + NaCl + C2H5ONa}}
Molten sodium was used.
Other organosilicon compounds synthesized using the Wurtz–Fittig reaction include silylated calixarenes{{Cite journal |title=The Wurtz–Fittig Reaction in the Preparation of C-Silylated Calixarenes |last1=Hudrlik |first1=Paul F. |last2=Arasho |first2=Wondwossen D. |last3=Hudrlik |first3=Anne M. |year=2007 |journal=The Journal of Organic Chemistry |volume=72 |issue=21 |pages=8107–8110 |doi=10.1021/jo070660n |pmid=17850095 |issn=0022-3263}} and vinylsilanes.{{Cite journal |last1=Adam |first1=Waldemar |last2=Richter |first2=Markus J. |year=1994 |title=One-Pot Synthesis of α-Trimethylsilyl Enones from Vinylsilanes |journal=Synthesis |volume=1994 |issue=2 |pages=176–180 |doi=10.1055/s-1994-25433 |issn=0039-7881}}
See also
References
{{Reflist}}
{{DEFAULTSORT:Wurtz-Fittig reaction}}
Category:Carbon-carbon bond forming reactions