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.
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| Names | |
|---|---|
| Preferred IUPAC name
2,6-Dimethylpyridine | |
| Other names
Lutidine | |
| Identifiers | |
3D model (JSmol) |
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| 105690 | |
| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.003.262 |
| EC Number |
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| 2863 | |
PubChem CID |
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| UNII | |
| UN number | 2734 |
CompTox Dashboard (EPA) |
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| |
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| 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]
See also
References
- Merck Index, 11th Edition, 5485.
- 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.
- Singer, Alvin; McElvain, S. M. (1934). "2,6-Dimethylpyridine". Org. Synth. 14: 30. doi:10.15227/orgsyn.014.0030.
- 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.
- 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.
- 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.
- 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.