Conformational analysis of N,N,N-Trimethyl-(3,3-dimethylbutyl)ammonium iodide by NMR spectroscopy: a sterically hindered trans-standard.
A predominantly trans-1,2-disubstituted ethane system - N,N,N-trimethyl-(3,3-dimethylbutyl)ammonium iodide - is of particular interest for conformational analysis, because it contains both an organic and a highly polar substituent, making it soluble and thus applicable to study in a large variety of solvents. The fraction of the trans conformer of this molecule in a wide range of protic and aprotic solvents was determined by the nuclear magnetic resonance proton couplings to be approximately 90%, in contrast to the previously assumed 100%. The consistently strong preference of the trans conformation should establish N,N,N-trimethyl-(3,3-dimethylbutyl)ammonium iodide as a possibly useful 'trans-standard' in conformational analysis, much more so than 1,2-ditert-butylethane, which has a poor solubility in many solvents.
Gates and Crellin Laboratories of Chemistry, California Institute of Technology, Pasadena, California, 91125.
Albert Tianxiang
AT
Liu
Mrinmoy
M
Nag
William R
WR
Carroll
John D
JD
Roberts
1H; N,N,N‐trimethyl‐(3,3‐dimethylbutyl)ammonium iodide; NMR; conformational analysis; trans‐standard