1-methylimidazole

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Structural formula
Structural formula of 1-methylimidazole
General
Surname 1-methylimidazole
other names

1-methyl-1 H -imidazole

Molecular formula C 4 H 6 N 2
Brief description

colorless liquid with a characteristic odor

External identifiers / databases
CAS number 616-47-7
EC number 210-484-7
ECHA InfoCard 100.009.532
PubChem 1390
ChemSpider 1348
DrugBank DB02671
Wikidata Q4545792
properties
Molar mass 82.10 g mol −1
Physical state

liquid

density

1.03 g cm −3

Melting point

-6 ° C

boiling point

198 ° C

Vapor pressure

0.4 hPa (20 ° C)

solubility

soluble in water

Refractive index

1.495 (20 ° C)

safety instructions
GHS labeling of hazardous substances
05 - Corrosive 06 - Toxic or very toxic

danger

H and P phrases H: 302-311-314
P: 280-301 + 312 + 330-301 + 330 + 331-303 + 361 + 353-305 + 351 + 338
Toxicological data
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

1-methylimidazole or N -methylimidazole is an organic compound from the group of five-membered, heterocyclic , aromatic amines having the empirical formula C 4 H 6 N 2 . It is a colorless liquid that is used as a solvent, base and as a starting material for the synthesis of some ionic liquids .

properties

1-Methylimidazole is a colorless, clear liquid with a melting point of -6 ° C. In contrast to imidazole , this compound cannot tautomerize. It is slightly more basic than imidzaol, as shown by the pKa values ​​of 7.0 and 7.4, respectively. The methylation of nitrogen leads to a lower melting point, which is why it is suitable as a solvent.

synthesis

1-Methylimidazole is manufactured industrially via two main routes. Most commonly, an acid-catalyzed methylation of imidazole with methanol is used. The second route uses a Radziszewski synthesis starting from glyoxal , formaldehyde and a mixture of ammonia and methylamine .

Radziszewski synthesis of 1-methylimidazole

On a laboratory scale, 1-methylimidazole can be obtained by methylating the pyridine-analogous nitrogen and subsequent deprotonation. An alternative route is the deprotonation of the imidazole and subsequent methylation of the salt.

Methylation of imidazole

application

1-Methylimidazole and its derivatives are used to mimic properties of imidazole-based biomolecules. It is also a starting material for the synthesis of pyrrole imidazole polyamides, which can bind selectively to DNA sequences.

Ionic liquids

Ionic liquids can be obtained by alkylating 1-methylimidazole . Depending on the alkylating agent, various combinations of anion and cation can be obtained.

Synthesis of ionic liquids starting from 1-methylimidazole

BASIL process

BASF uses 1-methylimidazole in the BASIL process ( biphasic acid scavenging using ionic liquids ). 1-methylimidazole is used as an auxiliary base to neutralize the hydrochloric acid that is formed. An ionic liquid is formed, which forms a second phase and can thus be easily separated. Diethoxyphenylphosphine is obtained in the BASIL process.

BASIL process

Donor properties

As a ligand, 1-methylimidazole (NMIz) forms octahedral ions M (NMIz) 6 2+ with M = Fe, Co, Ni, and square-planar ions with copper Cu (NMIz) 4 2+ .

safety instructions

The vapors of 1-methylimidazole can form an explosive mixture with air ( flash point 92 ° C, ignition temperature 525 ° C).

Individual evidence

  1. a b c Entry on 1-methylimidazole in the GESTIS substance database of the IFA , accessed on September 1, 2020(JavaScript required) .
  2. a b c d e f g h i Data sheet 1-methylimidazole from Sigma-Aldrich , accessed on August 17, 2020 ( PDF ).
  3. ^ Adrien Albert: Heterocyclic chemistry: an introduction. 2nd Edition. Athlone Press, London 1968, ISBN 0-485-11092-X (English).
  4. Klaus Ebel, Hermann Koehler, Armin O. Gamer, Rudolf Jäckh: Imidazole and Derivatives . In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany 2000, ISBN 3-527-30673-0 , p. a13_661 , doi : 10.1002 / 14356007.a13_661 (English, wiley.com [accessed on August 16, 2020]).
  5. Br. Radziszewski: About the constitution of Lophins and related connections . In: Reports of the German Chemical Society . tape 15 , no. 2 , July 1882, p. 1493-1496 , doi : 10.1002 / cber.18820150207 .
  6. ^ Gilchrist, Thomas Lonsdale: Heterocyclic chemistry . 2nd Edition. Longman Scientific & Technical, Harlow, Essex, England 1992, ISBN 0-582-06420-1 (English).
  7. Kumar, Mahendra, Gupta, Vandana: Heterocyclic chemistry . Springer, Berlin 1998, ISBN 3-540-64840-2 (English).
  8. Br. Radziszewski: About the constitution of Lophins and related connections . In: Reports of the German Chemical Society . tape 15 , no. 2 , July 1882, p. 1493-1496 , doi : 10.1002 / cber.18820150207 .
  9. Eldon E. Baird, Peter B. Dervan: Solid Phase Synthesis of Polyamides Containing Imidazole and Pyrrole Amino Acids . In: Journal of the American Chemical Society . Vol. 118, No. 26 , 1996, pp. 6141–6146 , doi : 10.1021 / ja960720z (English, caltech.edu [PDF]).
  10. Bkm Chan, N Chang, Mr Grimmett: The synthesis and thermolysis of imidazole quaternary salts . In: Australian Journal of Chemistry . tape 30 , no. 9 , 1977, ISSN  0004-9425 , pp. 2005 , doi : 10.1071 / CH9772005 (English).
  11. a b G. Wytze Meindersma, Matthias Maase, André B. De Haan: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH, Weinheim 2007, ISBN 978-3-527-30673-2 , Ionic Liquids, doi : 10.1002 / 14356007.l14_l01 (English).
  12. Preparation of 1-Butyl-3-Methyl Imidazolium-Based Room Temperature Ionic Liquids . In: Organic Syntheses . tape 79 , 2002, pp. 236 , doi : 10.15227 / orgsyn.079.0236 (English).
  13. Tom Welton: Solvents and sustainable chemistry . In: Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences . tape 471 , no. 2183 , November 8, 2015, ISSN  1364-5021 , p. 20150502 , doi : 10.1098 / rspa.2015.0502 , PMID 26730217 , PMC 4685879 (free full text) - (English).
  14. J. Reedijk: Pyrazoles and Imidazoles as ligands. II. Coordination compounds of N-methyl imidazole with metal perchlorates and tetrafluoroborates . In: Inorganica Chimica Acta . tape 3 , January 1969, p. 517-522 , doi : 10.1016 / S0020-1693 (00) 92544-1 (English).