3-Methylpyridine

3-Methylpyridine or 3-picoline, is an organic compound with formula 3-CH3C5H4N. It is one of three positional isomers of methylpyridine, whose structures vary according to where the methyl group is attached around the pyridine ring. This colorless liquid is a precursor to pyridine derivatives that have applications in the pharmaceutical and agricultural industries. Like pyridine, 3-methylpyridine is a colorless liquid with a strong odor and is classified as a weak base.[1]

3-Methylpyridine
Names
Preferred IUPAC name
3-Methylpyridine
Other names
3-Picoline
Identifiers
3D model (JSmol)
1366
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.003.307
EC Number
  • 203-636-9
2450
RTECS number
  • TJ5000000
UNII
UN number 2313
  • InChI=1S/C6H7N/c1-6-3-2-4-7-5-6/h2-5H,1H3
    Key: ITQTTZVARXURQS-UHFFFAOYSA-N
  • Cc1cccnc1
Properties
C6H7N
Molar mass 93.13 g/mol
Appearance Colorless liquid
Density 0.957 g/mL
Melting point −19 °C (−2 °F; 254 K)
Boiling point 144 °C (291 °F; 417 K)
Miscible
-59.8·10−6 cm3/mol
Hazards
GHS labelling:
GHS02: FlammableGHS05: CorrosiveGHS06: ToxicGHS07: Exclamation mark
Danger
H226, H302, H311, H314, H315, H319, H331, H332, H335
P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P280, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P311, P312, P321, P322, P330, P332+P313, P337+P313, P361, P362, P363, P370+P378, P403+P233, P403+P235, P405, P501
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

Synthesis

3-Methylpyridine is produced industrially by the reaction of acrolein, with ammonia. These ingredients are combined as gases which flows over an oxide-based heterogeneous catalyst. The reaction is multistep, culminating in cyclisation.

2  CH2CHCHO + NH3 → CH3C5H4N + 2 H2O

This process also affords substantial amounts of pyridine, which arises by demethylation of the 3-methylpyridine. A route that gives better control of the product starts with acrolein, propionaldehyde, and ammonia:[1]

CH2CHCHO + CH3CH2CHO + NH3 → 3-CH3C5H4N + 2 H2O + H2

It may also be obtained as a co-product of pyridine synthesis from acetaldehyde, formaldehyde, and ammonia via Chichibabin pyridine synthesis. Approximately 9,000,000 kilograms were produced worldwide in 1989. It has also been prepared by dehydrogenation of 3-methylpiperidine, derived from hydrogenation of 2-Methylglutaronitrile.[2]

Uses

3-Picoline is a useful precursor to agrochemicals, such as chlorpyrifos.[1] Chlorpyrifos is produced from 3,5,6-trichloro-2-pyridinol, which is generated from 3-picoline by way of cyanopyridine. This conversion involves the ammoxidation of 3-methylpyridine:

CH3C5H4N + 1.5 O2 + NH3 → NCC5H4N + 3 H2O

3-Cyanopyridine is also a precursor to 3-pyridinecarboxamide,[3][4][5] which is a precursor to pyridinecarbaldehydes:

3-NCC5H3N + [H] + catalyst → 3-HC(O)C5H4N

Pyridinecarbaldehydes are used to make antidotes for poisoning by organophosphate acetylcholinesterase inhibitors.

Environmental behavior

Pyridine derivatives (including 3-methylpyridine) are environmental contaminants, generally associated with processing fossil fuels, such as oil shale or coal.[6] They are also found in the soluble fractions of crude oil spills. They have also been detected at legacy wood treatment sites. The high water solubility of 3-methyl pyridine increases the potential for the compound to contaminate water sources. 3-methyl pyridine is biodegradable, although it degrades more slowly and volatilize more readily from water samples than either 2-methyl- or 4-methyl-pyridine.,[7][8]

3-Methylpyridine is the main precursor to niacin, one of the B vitamins. Approximately 10,000 tons of niacin are produced annually worldwide.[9]

See also

Toxicity

Like most alkylpyridines, the LD50 of 2-methylpyridine is modest, being 400 mg/kg (oral, rat).[9]

References
  1. Shinkichi Shimizu; Nanao Watanabe; Toshiaki Kataoka; Takayuki Shoji; Nobuyuki Abe; Sinji Morishita; Hisao Ichimura (2002). "Pyridine and Pyridine Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a22_399.
  2. Eric F. V. Scriven; Ramiah Murugan (2005). "Pyridine and Pyridine Derivatives". Kirk-Othmer Encyclopedia of Chemical Technology. XLI. doi:10.1002/0471238961.1625180919031809.a01.pub2. ISBN 0471238961.
  3. Nagasawa, Toru; Mathew, Caluwadewa Deepal; Mauger, Jacques; Yamada, Hideaki (1988). "Nitrile Hydratase-Catalyzed Production of Nicotinamide from 3-Cyanopyridine in Rhodococcus rhodochrous J1". Appl. Environ. Microbiol. 54 (7): 1766–1769. doi:10.1128/AEM.54.7.1766-1769.1988. PMC 202743. PMID 16347686.
  4. Hilterhaus, L.; Liese, A. (2007). "Building Blocks". In Ulber, Roland; Sell, Dieter (eds.). White Biotechnology. Advances in Biochemical Engineering / Biotechnology. Vol. 105. Springer Science & Business Media. pp. 133–173. doi:10.1007/10_033. ISBN 9783540456957. PMID 17408083.
  5. Schmidberger, J. W.; Hepworth, L. J.; Green, A. P.; Flitsch, S. L. (2015). "Enzymatic Synthesis of Amides". In Faber, Kurt; Fessner, Wolf-Dieter; Turner, Nicholas J. (eds.). Biocatalysis in Organic Synthesis 1. Science of Synthesis. Georg Thieme Verlag. pp. 329–372. ISBN 9783131766113.
  6. Sims, G. K. and E.J. O'Loughlin. 1989. Degradation of pyridines in the environment. CRC Critical Reviews in Environmental Control. 19(4): 309-340.
  7. Sims, G. K. and L.E. Sommers. 1986. Biodegradation of pyridine derivatives in soil suspensions. Environmental Toxicology and Chemistry. 5:503-509.
  8. Sims, G. K. and L.E. Sommers. 1985. Degradation of pyridine derivatives in soil. J. Environmental Quality. 14:580-584.
  9. Manfred Eggersdorfer; et al. (2000). "Vitamins". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a27_443. ISBN 3527306730.
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