3-Methylpyridine
Encyclopedia
3-Methylpyridine, or 3-picoline, is the organic compound
with formula 3-CH3C5H4N. It is one of the three isomers of methylpyridine
. This colorless liquid is a precursor to pyridine
derivatives that have applications in the pharmaceutical and agricultural industries. Like pyridine, 3-methylpyridine is a colourless liquid with a strong odor. It is classified as a weak base.
with ammonia
:
This reaction is nonselective and a more efficient route starts with acrolein
, propionaldehyde
, and ammonia
:
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.
. 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:
3-Cyanopyridine is also a precursor to 3-pyridinecarboxamide, which is an precursor to pyridinecarbaldehydes:
Pyridinecarbaldehydes are used to make antidotes for poisoning by organophosphate acetylcholinesterase inhibitors.
, one of the B vitamins
. 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
.
Niacin is also an important food 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 a precursor to many of commercial compounds including cancer drugs, antibacterial agents, and pesticides. Approximately 10,000,000 kilograms of niacin are produced annually worldwide.
Niacin is prepared by hydrolysis of nicotinonitrile, which, as described above, is generated by oxidation of 3-picoline. Oxidation can be effected by air, but ammoxidation
is more efficient. 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. The use of this catalyst/oxidizer combination is greener because it does not produce nitrogen oxides as do traditional ammoxidations.
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
with formula 3-CH3C5H4N. It is one of the three isomers of methylpyridine
Picoline
Picoline refers to three different methylpyridine isomers, all with the chemical formula C6H7N and a molar mass of 93.13 g mol−1. All three are colourless liquids at room temperature and pressure and are miscible with water and most organic solvents...
. This colorless liquid is a precursor to 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...
derivatives that have applications in the pharmaceutical and agricultural industries. Like pyridine, 3-methylpyridine is a colourless liquid with a strong odor. It is classified as a weak base.
Synthesis
3-Methylpyridine is produced industrially by the reaction of acroleinAcrolein
Acrolein is the simplest unsaturated aldehyde. It is produced widely but is most often immediately reacted with other products due to its instability and toxicity...
with 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...
:
- 2 CH2CHCHO + NH3 → 3-CH3C5H4N + 2 H2O
This reaction is nonselective and a more efficient route starts with acrolein
Acrolein
Acrolein is the simplest unsaturated aldehyde. It is produced widely but is most often immediately reacted with other products due to its instability and toxicity...
, propionaldehyde
Propionaldehyde
Propionaldehyde or propanal is the organic compound with the formula CH3CH2CHO. It is a saturated 3-carbon aldehyde and is a structural isomer of acetone...
, 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...
:
- CH2CHCHO + CH3CH2CHO + NH3 → 3-CH3C5H4N + 2 H2O + H2
It may also be obtained as a co-product of pyridine synthesis from 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...
via Chichibabin pyridine synthesis
Chichibabin pyridine synthesis
The Chichibabin pyridine synthesis -chē-bā-bēn) is a method for synthesizing pyridine rings. In its general form, the reaction can can be described as a condensation reaction of aldehydes, ketones, α,β-Unsaturated carbonyl compounds, or any combination of the above, in ammonia or ammonia...
. Approximately 9,000,000 kilograms were produced worldwide in 1989.
Uses
3-Picoline is a useful precursor to agrochemicals, such as chlorpyrifosChlorpyrifos
Chlorpyrifos is a crystalline organophosphate insecticide that inhibits acetylcholinesterase and is used to control insect pests. It is known by many trade names...
. 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:
- 3-CH3C5H4N + 1.5 O2 + NH3 → 3-NCC5H4N + 3 H2O
3-Cyanopyridine is also a precursor to 3-pyridinecarboxamide, which is an precursor to pyridinecarbaldehydes:
- 3-NCC5H3N + [H] + catalyst → 3-HC(O)C5H4N
Pyridinecarbaldehydes are used to make antidotes for poisoning by organophosphate acetylcholinesterase inhibitors.
Niacin
3-Methylpyridine is the main precursor to niacinNiacin
"Niacin" redirects here. For the neo-fusion band, see Niacin .Niacin is an organic compound with the formula and, depending on the definition used, one of the forty to eighty essential human nutrients.Niacin is one of five vitamins associated with a pandemic deficiency disease: niacin deficiency...
, one of the B vitamins
B vitamins
B vitamins are a group of water-soluble vitamins that play important roles in cell metabolism. The B vitamins were once thought to be a single vitamin, referred to as vitamin B . Later research showed that they are chemically distinct vitamins that often coexist in the same foods...
. 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
Nicotine
Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...
.
Niacin is also an important food 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 a precursor to many of commercial compounds including cancer drugs, antibacterial agents, and pesticides. Approximately 10,000,000 kilograms of niacin are produced annually worldwide.
Niacin is prepared by hydrolysis of nicotinonitrile, which, as described above, is generated by oxidation of 3-picoline. Oxidation can be effected by air, but ammoxidation
Ammoxidation
In chemistry, ammoxidation is an industrial process for the production of nitriles using ammonia and oxygen. The usual substrates are alkenes. It is sometimes called the Sohio process, acknowledging that ammoxidation was commercialized by Standard Oil of Ohio...
is more efficient. 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. The use of this catalyst/oxidizer combination is greener because it does not produce nitrogen oxides as do traditional ammoxidations.