3-Methylpyridine

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 + 2H2O 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: :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.{{cite journal

Uses

3-Picoline is a useful precursor to agrochemicals, such as chlorpyrifos.{{Ullmann :CH3C5H4N + 1.5O2 + NH3 → NCC5H4N + 3H2O

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. 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.,

3-Methylpyridine is the main precursor to niacin, one of the B vitamins. Approximately 10,000 tons of niacin are produced annually worldwide.{{cite journal |display-authors=etal}}

Toxicity

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

References

References

1. (1988). "Nitrile Hydratase-Catalyzed Production of Nicotinamide from 3-Cyanopyridine in ''Rhodococcus rhodochrous'' J1". [[Appl. Environ. Microbiol.]].
2. (2007). "White Biotechnology". [[Springer Science & Business Media]].
3. (2015). "Biocatalysis in Organic Synthesis 1". [[Georg Thieme Verlag]].
4. (January 1989). "Degradation of pyridines in the environment". Critical Reviews in Environmental Control.
5. (June 1986). "Biodegradation of pyridine derivatives in soil suspensions". Environmental Toxicology and Chemistry.
6. (October 1985). "Degradation of Pyridine Derivatives in Soil". Journal of Environmental Quality.