Since the early twentieth century, pyridine derivatives have been commercially important, but most prominently so during World War II and thereafter. Many pyridines of commercial interest find application in market areas where bioactivity is important, as in medicinal drugs and in agricultural products such as herbicides, insecticides, fungicides, and plant growth regulators. However, pyridines also have significant market applications outside the realm of bioactive ingredients. For instance, polymers made from pyridine-containing monomers are generally sold on the basis of their unique physical properties and function, rather than for any bioactivity. Pyridines can be classified as specialty chemicals because of a relatively lower sales volume than commodity chemicals. They are most often sold in the marketplace as chemical intermediates used to manufacture final consumer products.Pyridine compounds are defined by the presence of a six-membered heterocyclic ring consisting of five carbon atoms and one nitrogen atom. The carbon valencies not taken up in forming the ring are satisfied by hydrogen atoms. The arrangement of atoms is similar to benzene except that one of the carbon−hydrogen ring sets has been replaced by a nitrogen atom. The parent compound is pyridine itself (1). Substituents are indicated either by the numbering shown, 1 through 6, or by the Greek letters, α, β or γ. The Greek symbols refer to the position of the substituent relative to the ring nitrogen atom, and are usually used for naming monosubstituted pyridines. The ortho, meta, and para nomenclature commonly used for disubstituted benzenes is not used in naming pyridine compounds.Important commercial alkylpyridine compounds are α-picoline (2), βpicoline (3), γ-picoline (4), 2,6-lutidine (5), 3,5-lutidine (6), 5-ethyl-2-methylpyridine (7), and 2,4,6-collidine (8). In general, the alkylpyridines serve as precursors of many other substituted pyridines used in commerce. These further substituted pyridine compounds derived from alkylpyridines are in turn often used as intermediates in the manufacture of commercially useful final products.
PYRIDINE AND PYRIDINE DERIVATIVESSince the early twentieth century, pyridine derivatives have been commercially important, but most prominently so during World War II and thereafter. Many pyridines of commercial interest find application in market areas where bioactivity is important, as in medicinal drugs and in agricultural products such as herbicides, insecticides, fungicides, and plant growth regulators. However, pyridines also have significant market applications outside the realm of bioactive ingredients. For instance, polymers made from pyridine-containing monomers are generally sold on the basis of their unique physical properties and function, rather than for any bioactivity. Pyridines can be classified as specialty chemicals because of a relatively lower sales volume than commodity chemicals. They are most often sold in the marketplace as chemical intermediates used to manufacture final consumer produc...
