3-Methylpyridine

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3-Methylpyridine
Other names	3-picoline
Identifiers
CAS number	[108-99-6]
Properties
Molecular formula	C6H7N
Molar mass	93.13 g/mol
Appearance	Colorless liquid
Density	0.957 g/mL
Melting point	-19 °C
Boiling point	144 °C
Solubility in water	Miscible
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

3-Methylpyridine, or 3-picoline, is the compound with formula 3-CH₃C₅H₄N. 3-Methylpyridine is a colorless liquid that has an unpleasant odor similar to pyridine. It is used as a precursor to pyridine derivatives that have applications in the pharmaceutical and agricultural industries.

Contents 1 Synthesis 2 Uses 3 Chlorpyrifos 4 Niacin 5 See also 6 References

[edit] Synthesis

3-Methylpyridine is most simply prepared by the reaction of acrolein with ammonia:

2 CH₂CHCHO + NH₃ → 3-CH₃C₅H₄N + 2 H₂O

However, this reaction affords other derivatives. It is prepared more efficiently from acrolein, propionaldehyde, and ammonia:

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

Approximately 9000 t/a was produced worldwide in 1989. ^[1]

[edit] Uses

3-picoline is used as a precursor to pharmaceuticals and agrochemicals.

[edit] Chlorpyrifos

Chlorpyrifos, an insecticide, and fluazifop-butyl (herbicide) are examples of products made by 3-picoline.^[2]Chlorpyrifos is produced from 3,5,6-trichloro-2-pyridinol, which is generated from 3-picoline by way of pyridinecarboxamides to aminopyridines and then amino pyridines to pyridinols. Synthesis of 3,5,6-trichloro-2-pyridinol from 3-picoline:

3-CH₃C₅H₄N + 1.5 O₂ + NH₃ → 3-NCC₅H₄N + 3 H₂O

3-CH₃C₅H₄N + 1 H₂O + NH₃ → 3-H₂NC(O)C₅H₄N

3-H₂NC(O)C₅H₄N + NaOCl → 3-H₂NC₅H₄N + CO₂ + NaCl

3-H₂NC₅H₄N + NaNO₂ → 3-HOC₅H₄N + NH₃

3-HOC₅H₄N + 3 Cl₂ → 3-HOC₅HN-2,5,6-Cl₃ + 3 HCl

3-picoline is also a precursor to 3-pyridinecarbonitrile which is an important precursor to pyridinecarbaldehydes:

3-CH₃C₅H₄N + 3/2O₂ + NH₃ + catalyst → 3-NCC₅H₄N +3H₂O

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

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

[edit] Niacin

3-Methylpridine is the main precursor in the synthesis of Niacin. 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.^[3] Niacin is one of the vitamins of the B complex and is a macronutrient for humans and many animals. Without Niacin, a condition called pellagra develops. Niacin is a component in many multivitamins, breakfast cereals, and soft drinks. It is also an important 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 used as precursor to many of commercial compounds including cancer drugs, antibacterial, and pesticides. Approximately 10,000 tons of niacin are produced annually worldwide.^[4] Niacin is prepared by hydrolysis of nicotinonitrile, which is generated by oxidation of 3-picoline. Oxidation can be effected by air, but ammoxidation is more efficient.^[5]

3-CH₃C₅H₄N + NH₃ + 3/2O₂ + H₂ + catalyst → 3-NCC₅H₄N +3H₂O

3-NCC₅H₄N + NaOH → 3-C (O) NH₂H₄N

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.^[6]The use of this catalyst/oxidizer combination is greener because it does not produce nitrogen oxide as do traditional ammoxidations.

[edit] See also

• Picoline

[edit] 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. 
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:DOI: 10.1002/14356007.a22_399. 
3. ^ Manfred Eggersdorfer (2000). "Vitamins". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a27_443. 
4. ^ Manfred Eggersdorfer (2000). "Vitamins". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a27_443. 
5. ^ Basude Manohar, Benjaram M. Reddy (1998). "Vitamins". Ullmann's Encyclopedia of Industrial Chemistry 71: 141-146. doi:10.1002/(SICI)1097-4660(199802)71:2<141::AID-JCTB822>3.0.CO;2-E. 
6. ^ Sarah Everts (2008). "Clean Catalysis: Environmentally friendly synthesis of niacin generates less inorganic waste". Chemical & Engineering News.