2,6-Lutidine

Last updated
2,6-Lutidine [1]
2,6-Lutidine.svg
Names
Preferred IUPAC name
2,6-Dimethylpyridine
Other names
Lutidine
Identifiers
3D model (JSmol)
105690
ChEBI
ChemSpider
ECHA InfoCard 100.003.262 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 203-587-3
2863
PubChem CID
UNII
UN number 2734
  • InChI=1S/C7H9N/c1-6-4-3-5-7(2)8-6/h3-5H,1-2H3
    Key: OISVCGZHLKNMSJ-UHFFFAOYSA-N
  • CC1=CC=CC(C)=N1
Properties
C7H9N
Molar mass 107.153 g/mol
Appearancecolorless oily liquid
Density 0.9252
Melting point −5.8 °C (21.6 °F; 267.3 K)
Boiling point 144 °C (291 °F; 417 K)
27.2% at 45.3 °C
Acidity (pKa)6.72 [2]
−71.72×10−6 cm3/mol
Hazards
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
3
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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2,6-Lutidine is a natural heterocyclic aromatic organic compound with the formula (CH3)2C5H3N. It is one of several dimethyl-substituted derivative of pyridine, all of which are referred to as lutidines. It is a colorless liquid with mildly basic properties and a pungent, noxious odor.

Contents

Occurrence and production

It was first isolated from the basic fraction of coal tar and from bone oil. [1]

A laboratory route involves condensation of ethyl acetoacetate, formaldehyde, and an ammonia source to give a bis(carboxy ester) of a 2,6-dimethyl-1,4-dihydropyridine, which, after hydrolysis, undergoes decarboxylation. [3]

It is produced industrially by the reaction of formaldehyde, acetone, and ammonia. [2]

Uses

2,6-Lutidine has been evaluated for use as a food additive owing to its nutty aroma when present in solution at very low concentrations.

Due to the steric effects of the two methyl groups, 2,6-lutidine is less nucleophilic than pyridine. Protonation of lutidine gives lutidinium, [(CH3)2C5H3NH]+, salts of which are sometimes used as a weak acid because the conjugate base (2,6-lutidine) is so weakly coordinating. In a similar implementation, 2,6-lutidine is thus sometimes used in organic synthesis as a sterically hindered mild base. [4] One of the most common uses for 2,6-lutidine is as a non-nucleophilic base in organic synthesis. It takes part in the formation of silyl ethers as shown in multiple studies. [5] [6]

Oxidation of 2,6-lutidine with air gives 2,6-diformylpyridine:

C5H3N(CH3)2 + 2 O2 → C5H3N(CHO)2 + 2 H2O

2,6-Lutidine also finds application in the synthesis of Nifurpirinol [13411-16-0]. [7]

Biodegradation

The biodegradation of pyridines proceeds via multiple pathways. [8] Although pyridine is an excellent source of carbon, nitrogen, and energy for certain microorganisms, methylation significantly retards degradation of the pyridine ring. In soil, 2,6-lutidine is significantly more resistant to microbiological degradation than any of the picoline isomers or 2,4-lutidine. [9] Estimated time for complete degradation was over 30 days. [10]

See also

Toxicity

Like most alkylpyridines, the LD50 of 2,6-dimethylpyridine is modest, being 400 mg/kg (oral, rat). [2]

References

  1. 1 2 The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.). Merck. 1989. ISBN   091191028X.,5485
  2. 1 2 3 Shimizu, Shinkichi; Watanabe, Nanao; Kataoka, Toshiaki; Shoji, Takayuki; Abe, Nobuyuki; Morishita, Sinji; Ichimura, Hisao (2007). "Pyridine and Pyridine Derivatives". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a22_399. ISBN   978-3-527-30673-2.
  3. ↑ Singer, Alvin; McElvain, S. M. (1934). "2,6-Dimethylpyridine". Organic Syntheses. 14: 30. doi: 10.15227/orgsyn.014.0030 .
  4. ↑ Prudhomme, Daniel R.; Park, Minnie; Wang, Zhiwei; Buck, Jason R.; Rizzo, Carmelo J. (2000). "Synthesis of 2′-Deoxyribonucleosides: Β-3′,5′-Di-o-benzoylthymidine". Org. Synth. 77: 162. doi:10.15227/orgsyn.077.0162.
  5. ↑ Corey, E. J.; Cho, H.; Rücker, C.; Hua, D. H. (1981). "Studies with trialkylsilyltriflates: new syntheses and applications". Tetrahedron Letters. 22 (36): 3455–3458. doi:10.1016/s0040-4039(01)81930-4.
  6. ↑ Franck, Xavier; Figadère, Bruno; Cavé, André (1995). "Mild deprotection of tert-butyl and tert-amyl ethers leading either to alcohols or to trialkylsilyl ethers". Tetrahedron Letters. 36 (5): 711–714. doi:10.1016/0040-4039(94)02340-H. ISSN   0040-4039.
  7. ↑ Fujita, A., Nakata, M., Minami, S., Takamatsu, H. (1966). "Studies on Nitrofuran Derivatives. VI. : Synthesis of 2-(5-Nitro-2-furyl)vinylpyridinemethanol and 2-(5-Nitro-2-furyl)-vinylpyridinecarboxylic acid Derivatives". YAKUGAKU ZASSHI. 86 (11): 1014–1021. doi:10.1248/yakushi1947.86.11_1014 . Retrieved 21 October 2025.
  8. ↑ Philipp, Bodo; Hoff, Malte; Germa, Florence; Schink, Bernhard; Beimborn, Dieter; Mersch-Sundermann, Volker (2007). "Biochemical Interpretation of Quantitative Structure-Activity Relationships (QSAR) for Biodegradation of N-Heterocycles: A Complementary Approach to Predict Biodegradability". Environmental Science & Technology. 41 (4): 1390–1398. Bibcode:2007EnST...41.1390P. doi:10.1021/es061505d. PMID   17593747.
  9. ↑ Sims, G. K.; Sommers, L. E. (1985). "Degradation of pyridine derivatives in soil". Journal of Environmental Quality. 14 (4): 580–584. Bibcode:1985JEnvQ..14..580S. doi:10.2134/jeq1985.00472425001400040022x.
  10. ↑ Sims, G. K.; Sommers, L. E. (1986). "Biodegradation of Pyridine Derivatives in Soil Suspensions". Environmental Toxicology and Chemistry. 5 (6): 503–509. Bibcode:1986EnvTC...5..503S. doi:10.1002/etc.5620050601.
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