Mesitylene: Difference between revisions

|Watchedfields = changed

|verifiedrevid = 444009999

|Name = Mesitylene

|ImageFileL1_Ref = {{chemboximage|correct|??}}

|ImageFileL1 = 1,3,5-Trimethylbenzene.svg

|ImageNameL1 = Mesitylene

|ImageFileR1 = Mesitylene-3D-vdW.png

|ImageNameR1 = Mesitylene

|PIN = 1,3,5-Trimethylbenzene<ref name=iupac2013>{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = [[Royal Society of Chemistry|The Royal Society of Chemistry]] | date = 2014 | location = Cambridge | page = 139 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4}}</ref>

|OtherNames = Mesitylene<ref name=iupac2013 /><br />''sym''-Trimethylbenzene

|Section1 = {{Chembox Identifiers

|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

|ChemSpiderID = 7659

|PubChem = 7947

|KEGG_Ref = {{keggcite|correct|kegg}}

|KEGG = C14508

|InChI = 1/C9H12/c1-7-4-8(2)6-9(3)5-7/h4-6H,1-3H3

|InChIKey = AUHZEENZYGFFBQ-UHFFFAOYAK

|StdInChI_Ref = {{stdinchicite|correct|chemspider}}

|StdInChI = 1S/C9H12/c1-7-4-8(2)6-9(3)5-7/h4-6H,1-3H3

|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

|StdInChIKey = AUHZEENZYGFFBQ-UHFFFAOYSA-N

|CASNo_Ref = {{cascite|correct|CAS}}

|CASNo = 108-67-8

|UNII_Ref = {{fdacite|correct|FDA}}

|UNII = 887L18KQ6X

|EINECS = 203-604-4

|UNNumber = 2325

|ChEBI_Ref = {{ebicite|correct|EBI}}

|ChEBI = 34833

|SMILES = Cc1cc(cc(c1)C)C

}}

|Section2 = {{Chembox Properties

|Formula = C₉H₁₂

|MolarMass = 120.19 g/mol

|Density = 0.8637 g/cm³ at 20 °C

|MeltingPtC = −44.8

|BoilingPtC = 164.7

|Appearance = Colorless liquid<ref name=PGCH/>

|Odor = Distinctive, aromatic<ref name=PGCH/>

|Solubility = 0.002% (20°C)<ref name=PGCH/>

|VaporPressure = 2 mmHg (20°C)<ref name=PGCH/>

|MagSus = -92.32·10⁻⁶ cm³/mol

}}

|Section3 = {{Chembox Structure

|Dipole = 0.047 [[Debye|D]]<ref>{{Cite journal |doi = 10.1016/j.atmosenv.2004.01.019| title = Proton transfer reaction rate constants between hydronium ion (H₃O⁺) and volatile organic compounds |year = 2004 |last1 = Zhao| first1 = Jun |last2 = Zhang |first2 = Renyi |journal = Atmospheric Environment |volume = 38 |issue = 14 |pages = 2177–2185 | bibcode = 2004AtmEn..38.2177Z }}</ref>

}}

|Section7 = {{Chembox Hazards

|ExternalSDS = [https://www.sigmaaldrich.com/BE/en/sds/sial/m7200?sdslanguage=en]

|FlashPtF = 122

|FlashPt_ref = <ref name=PGCH>{{PGCH|0639}}</ref>

|IDLH = N.D.<ref name=PGCH/>

|REL = TWA 25 ppm (125 mg/m³)<ref name=PGCH/>

|PEL = none<ref name=PGCH/>

'''Mesitylene''' or '''1,3,5-trimethylbenzene''' is a derivative of [[benzene]] with three [[methyl]] [[substituent]]s positioned symmetrically around the ring. The other two isomeric [[trimethylbenzenes]] are [[1,2,4-trimethylbenzene]] (pseudocumene) and [[1,2,3-trimethylbenzene]] (hemimellitene). All three compounds have the [[chemical formula|formula]] C₆H₃(CH₃)₃, which is commonly abbreviated C₆H₃Me₃. Mesitylene is a colorless liquid with sweet aromatic odor. It is a component of [[coal tar]], which is its traditional source. It is a precursor to diverse [[fine chemical]]s. The '''mesityl''' group (Mes) is a substituent with the formula C₆H₂Me₃ and is found in various other compounds.<ref name=Ullmanns/>

==Preparation==

Mesitylene is prepared by [[transalkylation]] of [[xylene]] over solid [[acid catalyst]]:<ref name=Ullmanns>Karl Griesbaum, Arno Behr, Dieter Biedenkapp, Heinz-Werner Voges, Dorothea Garbe, Christian Paetz, Gerd Collin, Dieter Mayer, Hartmut Höke “Hydrocarbons” in Ullmann's Encyclopedia of Industrial Chemistry 2002 Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a13_227}}.</ref>

:2&nbsp;[[xylene|C₆H₄(CH₃)₂]]&nbsp;⇌&nbsp;C₆H₃(CH₃)₃&nbsp;+&nbsp;[[toluene|C₆H₅CH₃]]

:C₆H₄(CH₃)₂&nbsp;+&nbsp;CH₃OH&nbsp;→&nbsp;C₆H₃(CH₃)₃&nbsp;+&nbsp;H₂O

Although impractical, it could be prepared by trimerization of [[propyne]], also requiring an [[acid catalyst]], yields a mixture of 1,3,5- and 1,2,4-trimethylbenzenes.

[[Trimerization]] of [[acetone]] via [[aldol condensation]], which is catalyzed and [[dehydration|dehydrated]] by [[sulfuric acid]] is another method of synthesizing mesitylene.<ref>{{cite book

|last= Cumming

|first= W. M.

|date= 1937

|title= Systematic organic chemistry (3E)

|url= http://www.prepchem.com/synthesis-of-mesitylene/

|location= New York, USA

|publisher= D. Van Nostrand Company

|page=57

}}</ref>

==Reactions==

Oxidation of mesitylene with [[nitric acid]] yields [[trimesic acid]], C₆H₃(COOH)₃. Using [[manganese dioxide]], a milder [[oxidising agent]], 3,5-dimethyl[[benzaldehyde]] is formed. Mesitylene is oxidised by [[trifluoroperacetic acid]] to produce [[mesitol]] (2,4,6-trimethylphenol).<ref>{{cite book|pages = 242–243|chapter = Functional Compounds Containing Oxygen, Sulphur or Nitrogen and their Derivatives|chapter-url = https://books.google.com/books?id=XE5VHh7uL_0C&pg=PA242|title = Fluorine in Organic Chemistry|first = Richard D.|last = Chambers|publisher = [[CRC Press]]|year = 2004|isbn = 9780849317903}}</ref> Bromination occurs readily, giving [[mesityl bromide]]:<ref>{{cite journal|journal=Org. Synth.|year=1931|volume=11|page=24|doi=10.15227/orgsyn.011.0024|title=Bromomesitylene|author=Lee Irvin Smith}}</ref>

:(CH₃)₃C₆H₃ + Br₂ → (CH₃)₃C₆H₂Br + HBr

Mesitylene is a [[ligand]] in [[organometallic chemistry]], one example being the [[organomolybdenum chemistry|organomolybdenum]] complex {{nowrap|[([[hapticity|η⁶]]-C₆H₃Me₃)Mo(CO)₃]<ref>Girolami, G. S.; Rauchfuss, T. B. and Angelici, R. J., Synthesis and Technique in Inorganic Chemistry, University Science Books: Mill Valley, CA, 1999. {{ISBN|0-93570248-2}}.</ref>}} which can be prepared from [[molybdenum hexacarbonyl]].

==Applications==

Mesitylene is mainly used as a precursor to [[2,4,6-trimethylaniline]], a precursor to colorants. This derivative is prepared by selective mononitration of mesitylene, avoiding oxidation of the methyl groups.<ref name=Booth>{{cite encyclopedia|author=Gerald Booth|title=Nitro Compounds, Aromatic|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|year=2007|publisher=Wiley-VCH|location=Weinheim|doi=10.1002/14356007.a17_411|isbn=978-3527306732}}</ref>

===Niche uses===

[[File:(Mesitylene)molybdenum tricarbonyl.png|left|thumb|150px|Structure of (mesitylene)molybdenum tricarbonyl, [(η⁶-C₆H₃Me₃)Mo(CO)₃]]]

Mesitylene is used in the laboratory as a specialty solvent. In the electronics industry, mesitylene has been used as a [[photographic developer|developer]] for photopatternable [[silicone]]s due to its solvent properties.

The three [[aromatic]] hydrogen atoms of mesitylene are in identical chemical shift environments. Therefore, they only give a single peak near 6.8 ppm in the [[1H NMR|¹H NMR]] spectrum; the same is also true for the nine [[methyl group|methyl]] protons, which give a singlet near 2.3 ppm. For this reason, mesitylene is sometimes used as an [[internal standard]] in NMR samples that contain aromatic protons.<ref>{{Cite web|url=http://chemicalland21.com/industrialchem/organic/MESITYLENE.htm|title=Mesitylene (1,3,5-Trimethyl Benzene)}}</ref>

[[Uvitic acid]] is obtained by oxidizing mesitylene or by condensing [[pyruvic acid]] with [[Barium hydroxide|baryta water]].<ref>{{cite web|title=Definition of uvitic acid|url=http://www.merriam-webster.com/dictionary/uvitic%20acid|publisher=merriam-webster.com|accessdate=31 October 2016}}</ref>

The [[Gattermann reaction]] can be simplified by replacing the HCN/AlCl₃ combination with [[zinc cyanide]] (Zn(CN)₂).<ref name=simplfy>{{cite journal| author1 = Adams R. | last2=Levine | first2=I.| title = Simplification of the Gattermann Synthesis of Hydroxy Aldehydes| journal = [[J. Am. Chem. Soc.]]| year = 1923| volume = 45| pages = 2373–77| doi = 10.1021/ja01663a020| issue = 10| author1-link=Roger Adams }}</ref> Although it is highly toxic, Zn(CN)₂ is a solid, making it safer to work with than gaseous hydrogen cyanide (HCN).<ref name=Vol9>{{cite book|last1=Adams|first1=Roger|title=Organic Reactions, Volume 9|date=1957|publisher=John Wiley & Sons, Inc.|location=New York| pages = 38 & 53–54|isbn=9780471007265|doi=10.1002/0471264180.or009.02}}</ref> The Zn(CN)₂ reacts with the HCl to form the key HCN reactant and ZnCl₂ that serves as the Lewis-acid catalyst ''in-situ''. An example of the Zn(CN)₂ method is the synthesis of [[mesitaldehyde]] from mesitylene.<ref>{{OrgSynth| last1 =Fuson | first1=R. C. | last2=Horning |first2=E. C. |last3=Rowland |first3=S. P.|last4=Ward |first4=M. L.| title = Mesitaldehyde| collvol = 3| collvolpages = 549| year = 1955| doi=10.15227/orgsyn.023.0057}}</ref>

==History==

Mesitylene was first prepared in 1837 by [[Robert Kane (chemist)|Robert Kane]], an Irish chemist, by heating acetone with concentrated sulfuric acid.<ref>Robert Kane (1839) [https://archive.org/details/bub_gb_AuIcAQAAMAAJ/page/n589 <!-- pg=99 --> "On a series of combinations derived from pyroacetic spirit] [acetone]" ''Transactions of the Royal Irish Academy'', vol. 18, pages 99–125.</ref> He named his new substance "mesitylene" because the German chemist [[Carl Reichenbach]] had named acetone "mesit" (from the Greek μεσίτης, the mediator),<ref>Reichenbach's research is excerpted in: C. Reichenbach (1834) [https://books.google.com/books?id=P0s9AAAAcAAJ&pg=PA298 "Ueber Mesit (Essiggeist) und Holzgeist"] (On mesit (spirit of vinegar) and wood spirits), ''Annalen der Pharmacie'', vol. 10, no. 3, pages 298–314.</ref> and Kane believed that his reaction had dehydrated mesit, converting it to an [[alkene]], "mesitylene".<ref>For an explanation of the original of the name "mesitylene", see also: Henry E. Roscoe, ''A Treatise on Chemistry'' (New York, New York: D. Appleton and Co., 1889), vol. III, [https://archive.org/details/bub_gb_atXNAAAAMAAJ/page/n110 page 102], footnote 2.</ref> However, Kane's determination of the chemical composition ("empirical formula") of mesitylene was incorrect. The correct empirical formula was provided by [[August Wilhelm von Hofmann|August W. von Hofmann]] in 1849.<ref>A.W. Hofmann (1849) "On the composition of mesitilole [mesitylene], and some of its derivatives", ''The Quarterly Journal of the Chemical Society of London'', vol. 2, [https://books.google.com/books?id=oKAwAAAAYAAJ&pg=PA104 pages 104–115]. (Note: The empirical formula of mesitylene as stated in Hofmann's paper (C₁₈H₁₂ ) is incorrect; however, this happened because Hofmann used 6 as the atomic weight of carbon, instead of the correct atomic weight of 12. Once the correct atomic weight is used in Hofmann's calculations, his results give the correct empirical formula of C₉H₁₂.)</ref> In 1866 [[Adolf von Baeyer]] gave a correct mesitylene's empirical formula; however, with a wrong structure of tetracyclo[3.1.1.1^1,3.1^3,5]nonane.<ref>Adolf von Baeyer (1866) [https://books.google.com/books?id=yYlKAAAAYAAJ&pg=RA1-PA297 "Ueber die Condensationsproducte des Acetons"] (On condensation products of acetone), ''Annalen der Chemie und Pharmacie'', vol. 140, pages 297–306.</ref> A conclusive proof that mesitylene was trimethylbenzene was provided by [[Albert Ladenburg]] in 1874; however, assuming wrong benzene structure of [[prismane]].<ref>Albert Ladenburg (1874) "Ueber das Mesitylen" (On mesitylene), ''Berichte der deutschen chemischen Gesellschaft'', vol. 7, pages 1133–1137. {{doi| 10.1002/cber.18740070261}}</ref>

<gallery mode="packed" heights=120 caption="Historical mesitylene structures">

File:Mesitylen by Adolf von Baeyer.png|Mesitylene by Adolf von Baeyer (tetracyclo[3.1.1.1^1,3.1^3,5]nonane)

File:Mesitylen by Albert Ladenburg.png|Mesitylene by Albert Ladenburg (1,2,6-trimethylprismane)

</gallery>

==Mesityl group==

The group (CH₃)₃C₆H₂- is called '''mesityl''' (organic group symbol: Mes). Mesityl derivatives, e.g. [[tetramesityldiiron]], are typically prepared from the [[Grignard reagent]] (CH₃)₃C₆H₂MgBr.<ref>{{cite journal|title=Isoodurene|author=Lee Irvin Smith|journal=Org. Synth.|year=1931|volume=11|page=66|doi=10.15227/orgsyn.011.0066}}</ref> Due to its large steric demand, the mesityl group is used as a large blocking group in asymmetric catalysis (to enhance diastereo- or enantioselectivity) and organometallic chemistry (to stabilize low oxidation state or low coordination number metal centers). Larger analogues with even greater steric demand, for example '''2,6-diisopropylphenyl''' (Dipp) and the analogously named '''Tripp''' ((ⁱPr)₃C₆H₂, Is) and '''supermesityl''' ((''^t''Bu)₃C₆H₂, Mes*) groups, may be even more effective toward achieving these goals.

==Safety and the environment==

Mesitylene is also a major urban [[volatile organic compound]] (VOC) which results from [[combustion]]. It plays a significant role in aerosol and [[tropospheric ozone]] formation as well as other reactions in [[atmospheric chemistry]].{{citation needed|date=August 2022}}

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{{Hydrocarbons}}

[[Category:C3-Benzenes]]

[[Category:Aromatic solvents]]