The influence of the size and position of the alkyl groups in alkylimidazole molecules on their acid-base properties

✍ Scribed by Beniamin Lenarcik; Piotr Ojczenasz

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2002
• Tongue: English
• Weight: 36 KB
• Volume: 39
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570390206

✦ Synopsis

Dissociation constants of HL + acids, where L stands for 1-alkylimidazole, 1-alkyl-2-methylimidazole, 1-alkyl-2-ethylimidazole, 1-alkyl-2-propylimidazole, 1-alkyl-4-methylimidazole and 1-alkyl-2-ethyl-4methylimidazole, were determined potentiometrically. For each of the homologous series of these bases, a relationship has been derived between the pK a value and the number of carbon atoms in the hydrocarbon group for (CH 2 ) n ≤ 13. The basicity of the alkylimidazoles has been found to increase linearly with increasing carbon chain length. The slopes of straight plots of pK a = f(n CH2 ) have been found to increase with increasing basicity of homologous series of the alkylimidazoles.