Titrations in non-aqueous media: Conductimetric and spectrophotometric investigation of reactions between iodine and aliphatic amines in acetonitrile

Abstract

The reactions between iodine and methyl-, ethyl-, n-propyl- and n-butylamines were investigated conductimetrically and spectrophotometrically in acetonitrile. The mole ratios of iodine to the amines titrated are 1:2, 2:2, 3:2 and 4:2, respectively, indicating strongly the formation of anionic species of the types I −, I − 3, I − 5 and I − 7 and cationic species of the type [R 3N-I-NR 3] +. Although the conductivities of the primary amines do not show a regular order, the secondary and tertiary amines show orders at least at the first end-points. The order for secondary amines is Me 2NH>Et 2NH> n-Pr 2NH> n-Bu 2NH and for tertiary amines n-Bu 3N>Et 3N>Me 3N. The end-points of the conductimetric titrations are fairly sharp and can be used in the determination of these amines.