2-Methylpyridine, or 2-picoline, is the compound described with formula C₆H₇N. 2-Picoline is a colorless liquid that has an

unpleasant odor An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sense ...

similar to

pyridine Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a d ...

. It is mainly used to make vinylpyridine and the agrichemical

nitrapyrin Nitrapyrin is an organic compound with the formula ClC5H3NCCl3, and is described as a white crystalline solid with a sweet odor.It is used as a nitrification inhibitor and bactericide, which is applied to soils for the growing of agricultural crop ...

Synthesis

2-Picoline was the first

compound reported to be isolated in pure form. It was isolated from coal tar in 1846 by T. Anderson. This chemistry was practiced by Reilly Industries. It is now mainly produced by two principal routes. One method involves the condensation of

acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the mos ...

and

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

in the presence of an oxide catalyst. This method affords a mixture of 2- and 4-picolines: : Another method involves the condensation of acetone and acrylonitrile to give 5-oxohexanenitrile, which then cyclizes to give 2-picoline. Approximately 8000 t/a was produced worldwide in 1989.

Reactions

Most of the reactions of picoline are centered on the methyl group. For example, the principal use of 2-picoline is as a precursor of 2-vinylpyridine. The conversion is achieved by condensation with

formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...

: : The copolymer of 2-vinylpyridine,

butadiene 1,3-Butadiene () is the organic compound with the formula (CH2=CH)2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two viny ...

and

styrene Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concen ...

is used as an adhesive for textile tire cord. 2-Picoline is also a precursor to the agrichemical,

, which prevents loss of ammonia from fertilizers. Oxidation by

potassium permanganate Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as K+ and , an intensely pink to purple solution. Potassium permanganate is widely used in the c ...

affords

picolinic acid Picolinic acid is an organic compound with the formula C5H4N(CO2H). It is a derivative of pyridine with a carboxylic acid (COOH) substituent at the 2-position. It is an isomer of nicotinic acid and isonicotinic acid, which have the carboxyl s ...

: : Treatment of 2-methylpyridine with

butyllithium Butyllithium may refer to one of 5 isomeric organolithium reagents of which 3 are commonly used in chemical synthesis: * ''n''-Butyllithium, abbreviated BuLi or nBuLi * ''sec''-Butyllithium, abbreviated ''sec''-BuLi or sBuLi, has 2 stereoisomers, ...

results in deprotonation of the methyl group: :H₃CC₅H₄N + BuLi → LiH₂CC₅H₄N + BuH

Biodegradation

Like other pyridine derivatives, 2-methylpyridine is often reported as an environmental contaminant associated with facilities processing oil shale or coal, and has also been found at legacy wood treatment sites. The compound is readily degradable by certain microorganisms, such as ''Arthrobacter'' sp. strain R1 (ATTC strain number 49987), which was isolated from an aquifer contaminated with a complex mixture of pyridine derivatives. ''

Arthrobacter ''Arthrobacter'' (from the Greek, "jointed small stick”) is a genus of bacteria that is commonly found in soil. All species in this genus are Gram-positive obligate aerobes that are rods during exponential growth and cocci in their stationary ...

'' and closely related

Actinomycetota The ''Actinomycetota'' (or ''Actinobacteria'') are a phylum of all gram-positive bacteria. They can be terrestrial or aquatic. They are of great economic importance to humans because agriculture and forests depend on their contributions to soi ...

are often found associated with degradation of pyridine derivatives and other nitrogen heterocyclic compounds. 2-methypyridine and 4-methypyridine are more readily degraded and exhibit less volatilization loss from environmental samples than does 3-methypyridine.

Uses

2-Methylpyridine is an intermediate used in the production of some pharmaceutical drugs including

amprolium Amprolium is the organic compound sold as a coccidiostat used in poultry. It has many International Nonproprietary Names. __TOC__ Uses in coccidiosis treatment in poultry The drug is a thiamine analogue and blocks the thiamine transporter of ''E ...

picoplatin Picoplatin is a platinum-based antineoplastic agent in clinical development by Poniard Pharmaceuticals (previously NeoRx) for the treatment of patients with solid tumors. In Phase I and Phase II clinical trials, picoplatin demonstrated activity i ...

dimethindene Dimetindene , also sold under the brand name Fenistil, is an antihistamine/anticholinergic. It is a first generation selective H1 antagonist. Dimetindene is an atypical first generation H1 antagonist as it only minimally passes across the blood� ...

, and

encainide Encainide (trade name Enkaid) is a class Ic antiarrhythmic agent. It is no longer used because of its frequent proarrhythmic side effects. Synthesis See also * Iferanserin * Cardiac Arrhythmia Suppression Trial The Cardiac Arrhythmia Suppr ...

Toxicity

Like most alkylpyridines, the

LD50 In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is the ...

of 2-methylpyridine is modest, being 790 mg/kg (oral, rat).

References

{{DEFAULTSORT:Methylpyridine, 2- 2-Pyridyl compounds Foul-smelling chemicals