Natural abundance carbon-13 and deuterium NMR studies on the liquid and solid phases of tert-butyl chloride and tert-butyl nitrate

✍ Scribed by D. W. Aksnes; K. Ramstad; O. P. Bjørlykke

• Publisher: John Wiley and Sons
• Year: 1988
• Tongue: English
• Weight: 578 KB
• Volume: 26
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260261210

✦ Synopsis

NMR line widths (13C) and spin-lattice relaxation times (13C and 'H) were measured over a wide temperature region in liquid and solid tert-butyl chloride (1) and tert-butyl nitrate (2). Molecular self-diffusion, with activation energies in the range 29-37 kJ mol-', is responsible for the considerable line narrowing observed for the 13C resonances in solid I of these substances.

An analysis of the "C and 'H spin-lattice relaxation times (T,)

in the liquid and solid phases of 1 and 2 is reported. Rotational correlation times, activation energies and pre-exponential factors for the appropriate motions were obtained from the Arrhenius equation. The I3C and *H T, data suggest that the overall reorientation occurring in solid I of 1 and 2 is slightly retarded by the melting process. The 13C T, data show that the faster motion in the ordered phases of 1 and 2 is the uniaxial C3' reorientation with an activation energy of 12-14 kJ mol-', while the slower motion is the C, methyl reorientation with an activation energy of 12-13 kJ mol-'. KEY WORDS 13C and 'H NMR line width Relaxation Orientationally disordered compounds Molecular motion Correlation times Activation energies ',C and 'H relaxation time measurements are particularly suited to studies of molecular rotations in orientationally disordered cyrstals, since intermolecular contributions and dipolar interactions between like spins do not complicate the interpretation, unlike the 0749-1581/88/12