Aggregation and C-N rotation of the lithium salt of N,N-dimethyldiphenylacetamide.
[formula: see text] Two methyl 1H NMR signals for the Li salt of N,N-dimethyldiphenylacetamide are observed at low temperature and assigned to the monomer and dimer. From line shape analysis, the dimerization constant (K1,2) is 40 +/- 10 M-1 at 200 K (delta G degree = 1.5 kcal mol-1, delta H degree = 0.8 kcal mol-1, delta S degree = 12 eu) and the activation parameters are delta H++ = 5.5 kcal mol-1 and delta S++ = -18 eu. The C-N bond rotation is too fast to observe on the NMR time scale, indicating a rotation barrier of less than 10 kcal mol-1.
Kim
Y J
YJ
Department of Chemistry, University of California, Berkeley 94720-1460, USA.
Streitwieser
A
A
Chow
A
A
Fraenkel
G
G
D000081:Acetamides / Q000737:chemistry*; D018020:Lithium Compounds; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D013696:Temperature
D000081:Acetamides; D018020:Lithium Compounds