3-Methylpyridine
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| Names | |
|---|---|
| Other names
3-picoline | |
| Identifiers | |
108-99-6  | |
| ChEBI | CHEBI:39922 |
| ChEMBL | ChEMBL15722  |
| ChemSpider | 7682 |
| Jmol interactive 3D | Image |
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| 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 | |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| verify (what is ?) | |
| Infobox references | |
3-Methylpyridine or 3-picoline, is an organic compound with formula 3-CH3C5H4N. It is one of three isomers of methylpyridine. 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. It 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 is nonselective and a more efficient route starts with acrolein, propionaldehyde, and ammonia:
- 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. [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, 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.[3] 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.,[4][5]
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-carboxylic acid amide). Nicotinic acid was first synthesized in 1867 by oxidative degradation of nicotine.[6] 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.[6]
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.[6] 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.[7] The use of this catalyst/oxidizer combination is greener because it does not produce nitrogen oxides as do traditional ammoxidations.
See also
References
- ↑ 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.
- ↑ 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.
- ↑ 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.
- ↑ Sims, G. K. and L.E. Sommers. 1986. Biodegradation of pyridine derivatives in soil suspensions. Environmental Toxicology and Chemistry. 5:503-509.
- ↑ Sims, G. K. and L.E. Sommers. 1985. Degradation of pyridine derivatives in soil. J. Environmental Quality. 14:580-584.
- 1 2 3 Manfred Eggersdorfer; et al. (2000). "Vitamins". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a27_443.
- ↑ Sarah Everts (2008). "Clean Catalysis: Environmentally friendly synthesis of niacin generates less inorganic waste". Chemical & Engineering News. ISSN 0009-2347.