Knowledge Bank

The infrared spectra of a series of substituted 1, 3, 5 triazines have been obtained in order to identify bands characteristic of the triazine ring. Empirical correlation of the spectra of substituted 2, 4-diamino- and 2, 4, 6 triamino triazines confirms the assignment of strong bands near $1560cm-1$ and $1450cm-1$ to in-plane vibrations involving the ring. These bands are shifted to lower frequency in the spectra of cyanuric chloride, cyanuric acid and $N,N\prime \prime -$, trichloroisocyanuric acid. In the spectra of amino-substituted traizines the $1560cm-1$ band appears to be extremely consistent and stable, while the $1450cm-1$ absorption is more erratic, perhaps disappearing altogether in the spectra of two dialkyl-amino chloro triazines. The medium strength band occurring consistently near $813cm-1$ was assigned a ring vibrational origin also, and may be related to the $735cm-1$ $A2$ vibration of unsubstituted 1, 3, 5 triazine. The $813cm-1$ band, which has found analytical application previously in melamine determinations, has proved to be an excellent identifying characteristic of amino substituted triazines in general. The observed spectra of some mono-substituted melamines, trisubstituted melamines, diamino alkoxy triazines, and diamino chloro triazines will be presented.