
%0 Journal Article
%A Wasylishen, RE 
%A Barron, PF 
%A Doddrell, DM 
%T Molecular Reorientation in the Plastic Crystalline Phase of Tris
%J Australian Journal of Chemistry
%D 1979/04/01
%V 32
%N 4
%P 905-909
%K 
%R https://doi.org/10.1071/CH9790905
%U https://www.publish.csiro.au/paper/CH9790905 
%X Carbon-13 N.M.R. spectra of tris(hydroxymethyl)aminomethane (Tris) have been measured between 407 and 461 K. Proton-decoupled 13C N.M.R. spectra of solid Tris between 407 K and its melting point are relatively sharp (v½ < 30 Hz) indicating rapid overall molecular reorientation in this temperature range. It was not possible to detect a 13C N.M.R, signal for Tris below 407 K. The observed 13C N.M.R. spin-lattice relaxation times appear continuous across the solid &#8596; liquid phase transition. From the temperature dependence of T1, a rotational activation energy of 51.6 ± 6 kJ mol-1 is calculated, which indicates that the molecules must expend considerable energy in reorienting. The N.M.R. results are discussed in relation to previous differential scanning calorimetry and X-ray diffraction data which indicate that Tris undergoes a solid &#8596; solid transition at 407 K. 
