2,4,6-Trimethylpyridine

2,4,6-Trimethylpyridine (2,4,6-collidine) is an organic compound which belongs to the heterocycles (more precisely, heteroaromatics). It consists of a pyridine ring substituted with three methyl groups. It belongs to the substance group of the collidines, a group of six constitutional isomers. 2,4,6-trimethylpyridine is the most well-known isomer of this group.

2,4,6-Trimethylpyridine
Names
Preferred IUPAC name
2,4,6-Trimethylpyridine
Identifiers
ECHA InfoCard 100.003.286
UNII
Properties
C8H11N
Molar mass 121.18 g·mol−1
Appearance colourless liquid with pyridine-like smell[1]
Melting point -44,5 °C
Boiling point 171–172 °C[1]
35 g·l−1 (20 °C)[1]
Vapor pressure 4 hPa (20 °C)[1]
Acidity (pKa) 7.43 (25 °C)[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Properties

The compound has a refractive index of 1.4959 (25 °C).[3]

Preparation

2,4,6-Trimethylpyridine was isolated from Dippel's oil in 1854.[4][5] A synthesis can be carried out analogously to the Hantzsch's dihydropyridine synthesis from ethyl acetoacetate (as β-ketocarbonyl compound), acetaldehyde and ammonia in the ratio 2: 1: 1.[6]

Use

By oxidation of the methyl groups with potassium permanganate collidinic acid is obtained.[7]

2,4,6-Trimethylpyridine is used in organic syntheses (for example, for dehydrohalogenation[8]), by binding the formed hydrogen halides.

See also

References
  1. Record of 2,4,6-Trimethylpyridin in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 27 July 2017.
  2. Zvi Rappoport: CRC Handbook of Tables for Organic Compound Identification, Third Edition, CRC Press, Boca Raton, Florida, 1984, ISBN 0-8493-0303-6, S. 438.
  3. David R. Lide (ed.). "Physical Constants of Organic Compounds". CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, FL: CRC Press/Taylor and Francis. pp. 3–510. (Internet-Version: 2010).
  4. Collidin. In: Heinrich August Pierer, Julius Löbe (Hrsg.): Universal-Lexikon der Gegenwart und Vergangenheit. 4. Auflage. Band 4. Altenburg 1858, S. 262 (zeno.org).
  5. Friedrich Auerbach: „Ueber ein neues Collidin“, in: Berichte der deutschen chemischen Gesellschaft, 1892, 25 (2), S. 3485–3490 (doi:10.1002/cber.189202502219).
  6. T. Laue, A. Plagens: Namen- und Schlagwort-Reaktionen der Organischen Chemie, 5. Auflage, Teubner Verlag, Wiesbaden 2006, ISBN 3-8351-0091-2, S. 172.
  7. Hong-Lin Zhu; Wei Xu; Jian-Fei Wang; Yue-Qing Zheng (2012), "Synthesis, crystal structures and properties of two supramolecular polymers constructed by lanthanide with pyridine-2,4,6-tricarboxylic acid", Synthetic Metals (in German), vol. 162, no. 13–14, pp. 1327–1334, doi:10.1016/j.synthmet.2012.05.016
  8. Entry on Kollidin. at: Römpp Online. Georg Thieme Verlag, retrieved 27 July 2017.
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