Methylpyridine is the homologue of the pyridine. Pyridine belongs to aromatic hydrocarbon as well as six-membered ring. It is similar to benzene in some aspects but is also different from benzene in some aspects, e.g., there are non-isomers for toluene while there are three kinds of methylpyridine isomers, i.e., 2-methylpyridine [1], 3-methylpyridine [2] and 4-methylpyridine [3]. It has a relative molecular mass being 93.13. It is naturally presented in coal tar and is chemically active and can be subject to substitution on the nitrogen atom as well as oxidation on the side chain or condensation reaction with aldehydes and ketones under the catalysis of the alkaline.

[1] is also known as α- methyl pyridine, α- picoline. It is colorless liquid.
It has a strong irritating odor with a relative density of 0.9462, Melting point of -66.8 ℃, and boiling point of 128.8 ℃. It has a refractive index of 1.4957 and a flash point of 26 ℃. It can be dissolved in water and acetone and miscible with ethanol and ether. It is capable to forming an azeotropic mixture with water with the product content of 52% and azeotropic point of 93.5 ℃. Rat subjecting to oral administration have a LD50 of 1410 mg / kg.
Purpose: it can be used as the raw material for the production of 2-vinyl pyridine; pesticide raw materials, production of "fenchlorazole", "pyridine-2,5-dimethyl ester," " dipropyl pyridine-2, 5- dicarboxylate", "chloro pyridine", "Peacock dioxide morpholine acid "," 2-pyridyl oxime methyl iodide, "" picloram pyridine "and so on.

[2] is also known as β-picoline, β-picoline. It appears as transparent colorless liquid with irritating foul smell and slightly sweet flavor. It has a relative density of 0.9560, 0.9613 (15 ℃), melting point of -18.3 ℃, boiling point of 143.9 ℃, the refractive index of 1.5403 and a flash point of 36 ℃ (closed). It is miscible with water, ethanol and ether. This product can form an azeotropic mixture with water with the product content being 27% and azeotropic point of 96.7 ℃. This product is different from [1] and [3] with a poor methylation reactivity. It has a stimulating effect on the skin, and can also be absorbed through the skin with its vapor irritating the eyes and respiratory tract, causing inflammation, causing severe blisters, vomiting, headache and other symptoms. Rat subjecting to oral administration has a LD50 of 790mg / kg.
Applications: pesticide raw materials, production of herbicides, insecticides, germicides such as "nornicotine", "parinol" and rodenticides " 1-nitrophenyl-3-(3-pyridylmethyl)-ure" and so on; food additives; during the meat processing, addition of 2-methylpyridine which can bind to Myoglobin, can prevent oxidation and maintain the freshness of the meat; addition of [2] to the bread, cakes, rice products, dairy products, ham and sausages and other foods, can play a role of enhanced vitamin to be applied to medicine for substituting the function of vitamin B; as vitamin supplements, it can be supplemented to infant formula milk powder as well as milk powder, food and beverages of pregnant women; it can also be used as medicine for the treatment of niacin deficiency; it can be used as feed additives; it can be applied to the production of tobacco amide or replacement of nicotinamide; alcohol modifying agent; dye intermediates as well as the raw materials of rubber vulcanization agent and film sensitizing agent.

[3] is also known as γ- picoline and γ- picoline. It appears as colorless liquid and is flammable. It has unpleasant odor but a sweet taste. If contaminated with impurities, the color will gradually turn yellow. It has a relative density of 0.9558, melting point of 3.7 ℃, and boiling point 144.9 ℃. It has a refractive index of 1.5064 (17 ℃) and a flash point of 56 ℃. It can be dissolved in water, ethanol and ether. This product can form an azeotropic mixture with water with the product content of 63.5% and azeotropic point 97.4 ℃. It is irritating to the skin, eyes and mucous membrane. Because of its stench, even at a concentration of 1 × 10-6, its smell can also be felt which can facilitate early prevention. After the poisoning, there will be feeling of nausea, vomiting, headache with causing internal organs and central nervous system diseases in severe cases. Rat subjecting to oral administration has a LD50 of 1290mg / kg.

Applications: pharmaceutical raw materials for production of anti-tuberculosis drugs "isoniazid" antidepressants "nialamide," antidote "obidoxime chloride "; pesticide raw materials for production of pesticides and herbicides; it also used in dyes, rubber additive agent, waterproof fabric, resin curing agent; it is also the raw materials for nicotinaldehyde, 2-amino-4-methylpyridine (veterinary), pyridine-4-carboxylic acid (anticoagulant).