Titrations in non-aqueous media part II. basicity order of aliphatic amines in nitrobenzene solvent

Gündüz T., Gündüz N., Kiliç E., KENAR A., Çetinel G.

The Analyst, vol.3, no.9, pp.1099-1101, 1986 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 3 Issue: 9
  • Publication Date: 1986
  • Doi Number: 10.1039/an9861101099
  • Journal Name: The Analyst
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1099-1101
  • Keywords: Amines, Basicity order, Nitrobenzene solvent, Non-aqueous titration, Potentiometric titration
  • Ankara University Affiliated: Yes

Abstract

The relative basicity order of methyl-, ethyl-, propyl- and butylamines has been determined potentiometrically with perchloric acid in nitrobenzene solvent and found to be R3N > R2NH > RNH2 > NH3, where R = Et, n-Pr or n-Bu. However, for the methylamines, the order is Me2NH ≥ Me3N > MeNH2 > NH3. The orders in primary, secondary and tertiary amines are EtNH2 > MeNH2 > n-PrNH2 > n-BuNH 2 > NH3; Et2NH > Me2NH > n-Pr2NH > n-Bu2NH > NH3; and Et 3N > n-Pr3N ≥ n-Bu3N > Me3N > NH3. These results show that, in general, an increase in the number of alkyl groups increases the basicity of the amine, and that an increase in the size of the alkyl group decreases the basicity. n-Butylamine is a stronger base than branched-chain primary butylamines.