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2,6-Lutidine

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2,6-Lutidine
Names
Preferred IUPAC name 2,6-Dimethylpyridine
Other names Lutidine
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference 105690
ChEBI
ChemSpider
ECHA InfoCard 100.003.262 Edit this at Wikidata
EC Number
  • 203-587-3
Gmelin Reference 2863
PubChem CID
UNII
UN number 2734
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C7H9N/c1-6-4-3-5-7(2)8-6/h3-5H,1-2H3Key: OISVCGZHLKNMSJ-UHFFFAOYSA-N
SMILES
  • CC1=CC=CC(C)=N1
Properties
Chemical formula C7H9N
Molar mass 107.153 g/mol
Appearance colorless oily liquid
Density 0.9252
Melting point −5.8 °C (21.6 °F; 267.3 K)
Boiling point 144 °C (291 °F; 417 K)
Solubility in water 27.2% at 45.3 °C
Acidity (pKa) 6.72
Magnetic susceptibility (χ) −71.72×10 cm/mol
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 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 , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

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.

Occurrence and production

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

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.

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

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, , 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. 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.

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

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

Biodegradation

The biodegradation of pyridines proceeds via multiple pathways. 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. Estimated time for complete degradation was over 30 days.

See also

Toxicity

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

References

  1. ^ The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.). Merck. 1989. ISBN 091191028X., 5485
  2. ^ 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 978-3527306732.
  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. 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.
  8. 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.
  9. 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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