3-Methylpyridine

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{{nbsp}} CH₂CHCHO + NH₃ → CH₃C₅H₄N + 2{{nbsp}}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:

: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

| author = Eric F. V. Scriven

| author2 = Ramiah Murugan

| title = Pyridine and Pyridine Derivatives

| journal = Kirk-Othmer Encyclopedia of Chemical Technology

| year = 2005

| volume = XLI

| doi = 10.1002/0471238961.1625180919031809.a01.pub2

| isbn = 0471238961

}}

3-Picoline is a useful precursor to agrochemicals, such as chlorpyrifos.{{Ullmann

| author = Shinkichi Shimizu

| author2 = Nanao Watanabe

| author3 = Toshiaki Kataoka

| author4 = Takayuki Shoji

| author5 = Nobuyuki Abe

| author6 = Sinji Morishita

| author7 = Hisao Ichimura

| title = Pyridine and Pyridine Derivatives

| year = 2002

| doi = 10.1002/14356007.a22_399

| isbn = 3527306730

}} 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{{nbsp}}O₂ + NH₃ → NCC₅H₄N + 3{{nbsp}}H₂O

3-Cyanopyridine is also a precursor to 3-pyridinecarboxamide,{{cite journal|title = Nitrile Hydratase-Catalyzed Production of Nicotinamide from 3-Cyanopyridine in Rhodococcus rhodochrous J1|first1 = Toru|last1 = Nagasawa|first2 = Caluwadewa Deepal|last2 = Mathew|first3 = Jacques|last3 = Mauger|first4 = Hideaki|last4 = Yamada|journal = Appl. Environ. Microbiol.|year = 1988|volume = 54|issue = 7|pages = 1766–1769|doi = 10.1128/AEM.54.7.1766-1769.1988|pmid = 16347686|pmc = 202743| bibcode=1988ApEnM..54.1766N }}{{cite book|title = White Biotechnology|editor1-first = Roland|editor1-last = Ulber|editor2-first = Dieter|editor2-last = Sell|chapter = Building Blocks|volume = 105|series = Advances in Biochemical Engineering / Biotechnology|isbn = 9783540456957|doi = 10.1007/10_033|pages = 133–173|chapter-url = https://books.google.com/books?id=_tXoG93OWHgC&pg=PA141|publisher = Springer Science & Business Media|year = 2007|pmid = 17408083|last1 = Hilterhaus|first1 = L.|last2 = Liese|first2 = A.}}{{cite book|title = Biocatalysis in Organic Synthesis 1|series = Science of Synthesis|publisher = Georg Thieme Verlag|year = 2015|chapter = Enzymatic Synthesis of Amides|first1 = J. W.|last1 = Schmidberger|first2 = L. J.|last2 = Hepworth|first3 = A. P.|last3 = Green|first4 = S. L.|last4 = Flitsch|pages = 329–372|isbn = 9783131766113|editor1-first = Kurt|editor1-last = Faber|editor2-first = Wolf-Dieter|editor2-last = Fessner|editor3-first = Nicholas J.|editor3-last = Turner|chapter-url = https://books.google.com/books?id=8h_wBgAAQBAJ&pg=PA362}} 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.

Pyridine derivatives (including 3-methylpyridine) are environmental contaminants, generally associated with processing fossil fuels, such as oil shale or coal.{{Cite journal |last1=Sims |first1=Gerald K. |last2=O'Loughlin |first2=Edward J. |last3=Crawford |first3=Ronald L. |date=January 1989 |title=Degradation of pyridines in the environment |url=http://www.tandfonline.com/doi/abs/10.1080/10643388909388372 |journal=Critical Reviews in Environmental Control |language=en |volume=19 |issue=4 |pages=309–340 |doi=10.1080/10643388909388372 |bibcode=1989CRvEC..19..309S |issn=1040-838X|url-access=subscription }} 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.,{{Cite journal |last1=Sims |first1=Gerald K. |last2=Sommers |first2=Lee E. |date=June 1986 |title=Biodegradation of pyridine derivatives in soil suspensions |url=https://setac.onlinelibrary.wiley.com/doi/10.1002/etc.5620050601 |journal=Environmental Toxicology and Chemistry |language=en |volume=5 |issue=6 |pages=503–509 |doi=10.1002/etc.5620050601 |issn=0730-7268|url-access=subscription }}{{Cite journal |last1=Sims |first1=Gerald K. |last2=Sommers |first2=Lee E. |date=October 1985 |title=Degradation of Pyridine Derivatives in Soil |url=https://acsess.onlinelibrary.wiley.com/doi/10.2134/jeq1985.00472425001400040022x |journal=Journal of Environmental Quality |language=en |volume=14 |issue=4 |pages=580–584 |doi=10.2134/jeq1985.00472425001400040022x |bibcode=1985JEnvQ..14..580S |issn=0047-2425|url-access=subscription }}

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

| author = Manfred Eggersdorfer

| title = Vitamins

| journal = Ullmann's Encyclopedia of Industrial Chemistry

| year = 2000

| doi = 10.1002/14356007.a27_443

| isbn = 3527306730

|display-authors=etal}}

• Picoline

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

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Category:3-Pyridyl compounds