1-Methylimidazole
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Names | |||
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IUPAC name
1-Methylimidazole
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Other names
N-Methylimidazole
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Identifiers | |||
616-47-7 | |||
ChEBI | CHEBI:113454 | ||
ChEMBL | ChEMBL543 | ||
ChemSpider | 1348 | ||
Jmol 3D model | Interactive image Interactive image |
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Properties | |||
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) | ||
Vapor pressure | {{{value}}} | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references | |||
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,
Basicity
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.
Synthesis
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 + NaOH → H2C2N(NCH3)CH + H2O + NaI
Applications
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
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, a salt that is easily separated and deprotonated to regenerate 1-methylimidazole.[8]
- 2 MeC3N2H3 + C6H5PCl2 + 2 C2H5OH → 2 [MeC3N2H4]Cl + C6H5P(OC2H5)2
See also
References
- ↑ Albert, A., Heterocyclic Chemistry, 2nd ed.; 1968 Athlone Press, ISBN 0-485-11092-X
- ↑ Ebel, K., Koehler, H., Gamer, A. O., & Jäckh, R. "Imidazole and Derivatives." In Ullmann’s Encyclopedia of Industrial Chemistry; 2002 Wiley-VCH, doi:10.1002/14356007.a13_661
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Gilchrist, T. L., Heterocyclic Chemistry, 2nd ed.; 1992 Longman Scientific & Technical, ISBN 0-582-06420-1
- ↑ Grimmett, M. R., Imidazole and Benzimidazole Synthesis; 1997 Academic Press, ISBN 0-12-303190-7
- ↑ Gupta, R. R., Kumar, M., Gupta, V., Heterocyclic Chemistry II: Five Membered Heterocycles; 1999 Springer, ISBN 3-540-65252-3
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 8.0 8.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.; Lua error in package.lua at line 80: module 'strict' not found.