1-Methylimidazole (original) (raw)

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1-Methylimidazole
Names
Preferred IUPAC name 1-Methyl-1_H_-imidazole
Other names1-Methylimidazole_N_-Methylimidazole NMI
Identifiers
CAS Number 616-47-7 checkY
3D model (JSmol) Interactive imageInteractive image
Beilstein Reference 105197
ChEBI CHEBI:113454 checkY
ChEMBL ChEMBL543 checkY
ChemSpider 1348 checkY
DrugBank DB02671
ECHA InfoCard 100.009.532 Edit this at Wikidata
EC Number 210-484-7
Gmelin Reference 2403
PubChem CID 1390
UNII P4617QS63Y
CompTox Dashboard (EPA) DTXSID6052291
InChI InChI=1S/C4H6N2/c1-6-3-2-5-4-6/h2-4H,1H3 checkYKey: MCTWTZJPVLRJOU-UHFFFAOYSA-N checkYInChI=1/C4H6N2/c1-6-3-2-5-4-6/h2-4H,1H3Key: MCTWTZJPVLRJOU-UHFFFAOYAU
SMILES n1ccn(c1)CCn1ccnc1
Properties
Chemical formula C4H6N2
Molar mass 82.10 g/mol
Density 1.03 g/cm3
Melting point −6 °C (21 °F; 267 K)
Boiling point 198 °C (388 °F; 471 K)
Hazards
GHS labelling:
Pictograms GHS05: CorrosiveGHS07: Exclamation mark
Signal word Danger
Hazard statements H302, H312, H314
Precautionary statements P260, P264, P270, P280, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P322, P330, P363, P405, P501
Safety data sheet (SDS) Oxford MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). checkY verify (what is checkY☒N ?) Infobox references

Chemical compound

1-Methylimidazole or _N_-methylimidazole is an aromatic heterocyclic organic compound with the formula CH3C3H3N2. It is a colourless liquid that is used as a specialty solvent, a base, and as a precursor to some ionic liquids. It is a fundamental nitrogen heterocycle and as such mimics for various nucleoside bases as well as histidine and histamine.

With the _N_-methyl group, this particular derivative of imidazole cannot tautomerize. It is slightly more basic than imidazole, as indicated by the pKa's of the conjugate acids of 7.0 and 7.4.[1] Methylation also provides a significantly lower melting point, which makes 1-methylimidazole a useful solvent.

1-Methylimidazole is prepared mainly by two routes industrially. The main one is acid-catalysed methylation of imidazole by methanol. The second method involves the Radziszewski reaction from glyoxal, formaldehyde, and a mixture of ammonia and methylamine.[2][3]

(CHO)2 + CH2O + CH3NH2 + NH3 → H2C2N(NCH3)CH + 3 H2O

The compound can be synthesized on a laboratory scale by methylation of imidazole at the pyridine-like nitrogen and subsequent deprotonation.[4] Similarly, 1-methylimidazole may be synthesized by first deprotonating imidazole to form a sodium salt followed by methylation.[5][6]

H2C2N(NH)CH + CH3I → [H2C2(NH)(NCH3)CH]I

[H2C2(NH)(NCH3)CH]I + NaOH → H2C2N(NCH3)CH + H2O + NaI

In the research laboratory, 1-methylimidazole and related derivatives have been used as mimic aspects of diverse imidazole-based biomolecules.

1-Methylimidazole is also the precursor for the synthesis of the methylimidazole monomer of pyrrole-imidazole polyamides. These polymers can selectively bind specific sequences of double-stranded DNA by intercalating in a sequence dependent manner.[7]

Ionic liquid precursor

[edit]

1-Methylimidazole alkylates to form dialkyl imidazolium salts. Depending on the alkylating agent and the counteranion, various ionic liquids result, e.g. 1-butyl-3-methylimidazolium hexafluorophosphate ("BMIMPF6"):[8][9]

BASF has used 1-methylimidazole as a means to remove acid during their industrial-scale production of diethoxyphenylphosphine. In this biphasic acid scavenging using ionic liquids (BASIL) process, 1-methylimidazole reacts with HCl to produce 1-methylimidazolium hydrochloride, which spontaneously separates as a separate liquid phase under the reaction conditions.[8][10]

2 MeC3N2H3 + C6H5PCl2 + 2 C2H5OH → 2 [MeC3N2H4]Cl + C6H5P(OC2H5)2

1-methylimidazole (NMIz) as a ligand forms octahedral ions M(NMIz)62+with M = Fe, Co, Ni, and a square-planar ion Cu(NMIz)42+. [11]1-methylimidazole forms adducts with Lewis acids such as molybdenum perfluorobutyrate and [Rh(CO)2Cl]2. The donor properties of 1-methylimidazole have been analyzed by the ECW model yielding EB= 1.16 and CB= 4.92.

  1. ^ Albert, A., Heterocyclic Chemistry, 2nd ed.; 1968 Athlone Press, ISBN 0-485-11092-X
  2. ^ Ebel, K.; Koehler, H.; Gamer, A. O. & Jäckh, R. (2002). "Imidazole and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_661. ISBN 978-3527306732.
  3. ^ Bronislaw Radziszewski (1882). "Ueber die Constitution des Lophins und verwandter Verbindungen" [By the Constitution of the Lophins and related compounds]. Berichte der deutschen chemischen Gesellschaft (in German). 15 (2): 1493–1496. doi:10.1002/cber.18820150207.
  4. ^ Gilchrist, T. L., Heterocyclic Chemistry, 2nd ed.; 1992 Longman Scientific & Technical, ISBN 0-582-06420-1
  5. ^ Grimmett, M. R., Imidazole and Benzimidazole Synthesis; 1997 Academic Press, ISBN 0-12-303190-7
  6. ^ Gupta, R. R., Kumar, M., Gupta, V., Heterocyclic Chemistry II: Five Membered Heterocycles; 1999 Springer, ISBN 3-540-65252-3
  7. ^ Baird, Eldon E.; Dervan, Peter B. (1996). "Solid Phase Synthesis of Polyamides Containing Imidazole and Pyrrole Amino Acids" (PDF). Journal of the American Chemical Society. 118 (26): 6141–6. doi:10.1021/ja960720z.
  8. ^ a b Meindersma, G. Wytze; Maase, Matthias; De Haan, André B. (2007). "Ionic Liquids". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.l14_l01. ISBN 978-3-527-30673-2.
  9. ^ Dupont, J.; Consorti, C.; Suarez, P.; de Souza, R. (2002). "Preparation of 1-Butyl-3-methyl imidazolium-based Room Temperature Ionic Liquids". Organic Syntheses. 79: 236. doi:10.15227/orgsyn.079.023.
  10. ^ Welton, Tom (11 November 2015). "Solvents and sustainable chemistry". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 471 (2183): 20150502. Bibcode:2015RSPSA.47150502W. doi:10.1098/rspa.2015.0502. PMC 4685879. PMID 26730217.Open access icon
  11. ^ Reedijk,R. (1969). "Pyrazoles and imidazoles as ligands. II. Coordination compounds of N-methyl imidazole with metal perchlorates and tetrafluoroborates". Inorganica Chimica Acta. 3: 517–522. doi:10.1016/S0020-1693(00)92544-1.