Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one methine group (=CH−) replaced by a nitrogen atom (=N−). It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow, due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. As of 2016, it is synthesized on the scale of about 20,000 tons per year worldwide.
Quinoline is a heterocyclic aromatic organic compound with the chemical formula C9H7N. It is a colorless hygroscopic liquid with a strong odor. Aged samples, especially if exposed to light, become yellow and later brown. Quinoline is only slightly soluble in cold water but dissolves readily in hot water and most organic solvents. Quinoline itself has few applications, but many of its derivatives are useful in diverse applications. A prominent example is quinine, an alkaloid found in plants. Over 200 biologically active quinoline and quinazoline alkaloids are identified. 4-Hydroxy-2-alkylquinolines (HAQs) are involved in antibiotic resistance.
Isonicotinic acid or pyridine-4-carboxylic acid is an organic compound with the formula C5H4N(CO2H). It is a derivative of pyridine with a carboxylic acid substituent at the 4-position. It is an isomer of picolinic acid and nicotinic acid, which have the carboxyl group at the 2- and 3-position respectively compared to the 4-position for isonicotinic acid.
Picolinic acid is an organic compound with the formula NC5H4CO2H. 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 side chain at the 3- and 4-positions, respectively. It is a white solid although impure samples can appear tan. The compound is soluble in water.
The Chichibabin pyridine synthesis is a method for synthesizing pyridine rings. The reaction involves the condensation reaction of aldehydes, ketones, α,β-Unsaturated carbonyl compounds, or any combination of the above, with ammonia. It was reported by Aleksei Chichibabin in 1924. Methyl-substituted pyridines, which show widespread uses among multiple fields of applied chemistry, are prepared by this methodology.
Picoline refers to any of three isomers of methylpyridine (CH3C5H4N). They are all colorless liquids with a characteristic smell similar to that of pyridine. They are miscible with water and most organic solvents.
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. It is mainly used to make vinylpyridine and the agrichemical nitrapyrin.
3-Methylpyridine or 3-picoline, is an organic compound with formula 3-CH3C5H4N. It is one of three positional isomers of methylpyridine, whose structures vary according to where the methyl group is attached around the pyridine ring. This colorless liquid is a precursor to pyridine derivatives that have applications in the pharmaceutical and agricultural industries. Like pyridine, 3-methylpyridine is a colorless liquid with a strong odor and is classified as a weak base.
Pyridine-N-oxide is the heterocyclic compound with the formula C5H5NO. This colourless, hygroscopic solid is the product of the oxidation of pyridine. It was originally prepared using peroxyacids as the oxidising agent. The compound is used infrequently as an oxidizing reagent in organic synthesis.
2,6-Di-tert-butylpyridine is an organic compound with the formula (Me3C)2C5H3N. This colourless, oily liquid is derived from pyridine by replacement of the two H atoms with tert-butyl groups. It is a hindered base. For example, it can be protonated, but it does not form an adduct with boron trifluoride.
Pyridine-2-carbaldehyde, also called 2-formylpyridine, is an organic compound with the formula NC5H4CHO. It is one of three isomeric pyridinaldehydes. The other isomers are pyridine-3-carboxaldehyde and pyridine-4-carboxaldehyde.
Chloro(pyridine)cobaloxime is a coordination compound containing a CoIII center with octahedral coordination. It has been considered as a model compound of vitamin B12 for studying the properties and mechanism of action of the vitamin. It belongs to a class of bis(dimethylglyoximato)cobalt(III) complexes with different axial ligands, called cobaloximes. Chloro(pyridine)cobaloxime is a yellow-brown powder that is sparingly soluble in most solvents, including water.
2-Vinylpyridine is an organic compound with the formula CH2CHC5H4N. It is a derivative of pyridine with a vinyl group in the 2-position, next to the nitrogen. It is a colorless liquid, although samples are often brown. It is used industrially as a precursor to specialty polymers and as an intermediate in the chemical, pharmaceutical, dye, and photo industries. Vinylpyridine is sensitive to polymerization. It may be stabilized with a polymerisation inhibitor such as tert-butylcatechol. Owing to its tendency to polymerize, samples are typically refrigerated.
2-Methylglutaronitrile is the organic compound with the formula NCCH2CH2CH(CH3)CN. This dinitrile is obtained in the large-scale synthesis of adiponitrile. It is a colorless liquid with an unpleasant odor. It is the starting compound for the vitamin nicotinamide and for the diester dimethyl-2-methylglutarate and the ester amide methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, which are promoted as green solvents. 2-Methylglutaronitrile is chiral but is mainly encountered as the racemate. It is also used to make Dytek A.
Nicotinonitrile or 3-cyanopyridine is an organic compound with the formula NCC5H4N. The molecule consists of a pyridine ring with a nitrile group attached to the 3-position. A colorless solid, it is produced by ammoxidation of 3-methylpyridine:
4-Vinylpyridine (4-VP) is an organic compound with the formula CH2CHC5H4N. It is a derivative of pyridine with a vinyl group in the 4-position. It is a colorless liquid, although impure samples are often brown. It is a monomeric precursor to specialty polymers. 4-Vinylpyridine is prepared by the condensation of 4-methylpyridine and formaldehyde.
Cyanoethylation is a process for the attachment of CH2CH2CN group to another organic substrate. The method is used in the synthesis of organic compounds.
3,5-Lutidine is a heterocyclic organic compound with the formula (CH3)2C5H3N. It is one of several dimethyl-substituted derivatives of pyridine, all of which are referred to as lutidines. It is a colorless liquid with mildly basic properties and a pungent odor. The compound is a precursor to the drug omeprazole.
5-Ethyl-2-methylpyridine is an organic compound with the formula (C2H5)(CH3)C5H3N. One of several isomeric pyridines with this formula, this derivative is of interest because it is efficiently prepared from simple reagents and it is a convenient precursor to nicotinic acid, a form of vitamin B3. 5-Ethyl-2-methylpyridine is a colorless liquid.
2,4,6-Tri-tert-butylpyrimidine is the organic compound with the formula HC(ButC)2N2CtBu where tBu = (CH3)3C. It is a substituted derivative of the heterocycle pyrimidine. Known also as TTBP, this compound is of interest as a base that is sufficiently bulky to not bind boron trifluoride but still able to bind protons. It is less expensive that the related bulky derivatives of pyridine such as 2,6-di-tert-butylpyridine, 2,4,6-tri-tert-butylpyridine, and 2,6-di-tert-butyl-4-methylpyridine.
