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.
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.
== Isomers == {| class="sortable wikitable" |- ! Name(s) ! CAS# ! m.p. (°C) ! b.p. (°C) ! pKa of pyridinium ion ! structure |- | 2-Methylpyridine, α-picoline, 2-picoline | [109-06-8] | −66.7 | 129.4 | 5.96 | class=skin-invert-image|90px| |- | 3-Methylpyridine, β-picoline, 3-picoline | [108-99-6] | −18 | 141 | 5.63 |class=skin-invert-image|90px| |- | 4-Methylpyridine, γ-picoline, 4-picoline | [108-89-4] | 3.6 | 145.4 | 5.98 |class=skin-invert-image|48px| |- |} The CAS number of an unspecified picoline isomer is [1333-41-1]. The methyl group in 2- and 4- picolines is reactive; e.g., 2-picolines condenses with acetaldehyde in the presence of warm aqueous sodium hydroxide to form 2-propenylpyridine.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).