2-Methylpyridine, or 2-picoline, is the compound described with formula C₆H₇N. 2-picoline is a colorless liquid that has an unpleasant odor similar to pyridine. Pyridines including 2-picoline are most crudely prepared by the reaction of acetylene and hydrogen cyanide.

Synthesis

2-Picoline was the first pyridine

Pyridine

Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...

 compound reported to be isolated in pure form. It was isolated from coal tar in 1846 by T. Anderson. It is now mainly produced by two principal routes, the condensation of acetaldehyde

Acetaldehyde

Acetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants as part...

, formaldehyde

Formaldehyde

Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

, and ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 and the cyclization of nitrile

Nitrile

A nitrile is any organic compound that has a -C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, one example being super glue .Inorganic compounds containing the -C≡N group are not called...

s and acetylene

Acetylene

Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...

. One example of such reaction is the combination of acetaldehyde and ammonia:

Approximately 8000 t/a was produced worldwide in 1989.

Uses

The principal application of 2-picoline is as a precursor of 2-vinylpyridine. The formation of 2-vinylpyridine is achieved by the addition of aqueous formaldehyde to 2-picoline, followed by a dehydration of the resulting alcohol:

The copolymerization of 2-vinylpyridine, butadiene and styrene is used as an adhesive for textile tire cord. 2-Picoline is also a precursor to the agrichemical, nitrapyrin, which prevents loss of ammonia from fertilizers.

2-Picoline is a versatile building block and can be used as a precursor to a variety of derivatives. For example, oxidation by potassium permanganate

Potassium permanganate

Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...

 affords picolinic acid:

Environmental Behavior

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. Owing to high water solubility, 2-methylpyridine has significant potential for mobility in the environment, which may promote water contamination. The compound is, however, 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

Arthrobacter 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 phase....

 and closely related Actinobacteria

Actinobacteria

Actinobacteria are a group of Gram-positive bacteria with high guanine and cytosine content. They can be terrestrial or aquatic. Actinobacteria is one of the dominant phyla of the bacteria....

are often found associated with degradation of pyridine derivatives and other nitrogen heterocyclic compounds.