3-Methylpyridine

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3-Methylpyridine
3-methylpyridine-2D-skeletal.png
Names
Preferred IUPAC name
3-Methylpyridine
Other names
3-Picoline
Identifiers
3D model (JSmol)
1366
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.003.307 Edit this at Wikidata
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
Signal word
 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

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.

Synthesis[]

3-Methylpyridine is produced industrially by the reaction of acrolein with ammonia:

2 CH2CHCHO + NH3 → 3-CH3C5H4N + 2 H2O

This reaction also affords substantial amounts of pyridine. A route that gives better control of the product starts with acrolein, propionaldehyde, and ammonia:

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

In practice, this reaction also produces substantial amounts of pyridine as a result of dealkylation of the 3-methylpyridine over the oxide catalyst. 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.[1]

Uses[]

3-Picoline is a useful precursor to agrochemicals, such as chlorpyrifos.[2] 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:

3-CH3C5H4N + 1.5 O2 + NH3 → 3-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]

Niacin[]

3-Methylpyridine is the main precursor to niacin, one of the B vitamins. Niacin is the generic name for both nicotinic acid and nicotinamide (pyridine 3-carboxylic acid and pyridine 3-carboxamide, respectively). Nicotinic acid was first synthesized in 1867 by oxidative degradation of nicotine.[9] Niacin is also an important food additive for domestic and farm animals; more than 60% of the niacin produced is consumed by poultry, swine, ruminants, fish, and pets. Along with its use as an essential vitamin, niacin is also a precursor to many of commercial compounds including cancer drugs, antibacterial agents, and pesticides. Approximately 10,000,000 kilograms of niacin are produced annually worldwide.[9]

Niacin is prepared by hydrolysis of nicotinonitrile, which, as described above, is generated by oxidation of 3-picoline. Oxidation can be effected by air, but ammoxidation is more efficient.[9] The catalysts used in the reaction above are derived from the oxides of antimony, vanadium, and titanium. New "greener" catalysts are being tested using manganese-substituted aluminophosphates that use acetyl peroxyborate as non-corrosive oxidant.[10] The use of this catalyst/oxidizer combination is greener because it does not produce nitrogen oxides as do traditional ammoxidations.

See also[]

Toxicity[]

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

References[]

  1. ^ 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.
  2. ^ 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. doi:10.1002/14356007.a22_399. ISBN 3527306730.
  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. 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. ^ a b c d Manfred Eggersdorfer; et al. (2000). "Vitamins". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a27_443. ISBN 3527306730.
  10. ^ Sarah Everts (2008). "Clean Catalysis: Environmentally friendly synthesis of niacin generates less inorganic waste". Chemical & Engineering News. ISSN 0009-2347.
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