
TY  - JOUR
A1  - Wasylishen, RE 
A1  - Barron, PF 
A1  - Doddrell, DM 
T1  - Molecular Reorientation in the Plastic Crystalline Phase of Tris
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1979
VL  - 32
IS  - 4
SP  - 905
EP  - 909
KW  - 
UR  - https://doi.org/10.1071/CH9790905 
N2  - 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. 
ER  -

