2,6-Lutidine

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.

2,6-Lutidine[1]
Names
Preferred IUPAC name
2,6-Dimethylpyridine
Other names
Lutidine
Identifiers
3D model (JSmol)
105690
ChEBI
ChemSpider
ECHA InfoCard 100.003.262
EC Number
  • 203-587-3
2863
UNII
UN number 2734
Properties
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)
27.2% at 45.3 °C
Acidity (pKa) 6.72[2]
-71.72·10−6 cm3/mol
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

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, acetaldehyde, 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 only weakly nucleophilic. 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]

Biodegradation

The biodegradation of pyridines proceeds via multiple pathways.[5] 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.[6] Estimated time for complete degradation was >30 days.[7]

gollark: Or bugfixes internally.
gollark: What about security updates?
gollark: Someone would still have to go to every workspace and go "update-util" *every time* a dependency updates.
gollark: That's still quite problematic.
gollark: Ale32bit made cget, and that has important packages like potatOS, but it's not very widely adopted and I'm not sure if it handles dependencies well.

See also

References
  1. Merck Index, 11th Edition, 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.
  3. Singer, Alvin; McElvain, S. M. (1934). "2,6-Dimethylpyridine". Org. Synth. 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. 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: 1390–1398. doi:10.1021/es061505d. PMID 17593747.
  6. Sims, G. K.; Sommers, L.E. (1985). "Degradation of pyridine derivatives in soil". Journal of Environmental Quality. 14 (4): 580–584. doi:10.2134/jeq1985.00472425001400040022x.
  7. Sims, G. K.; Sommers, L.E. (1986). "Biodegradation of Pyridine Derivatives in Soil Suspensions". Environmental Toxicology and Chemistry. 5 (6): 503–509. doi:10.1002/etc.5620050601.
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