AbstractIt is well known that the intermolecular hydrogen bonding is concentration and temperature dependent. It is also well known that : 1H chemical shift of a hydroxyl proton is dependent on concentration and temperature. 1H NMR has been used to study hydrogen bonding in solution.
It was found previously by Becker, Liddel and Schoolery that at very high dilution in CCl4, the chemical shift of the hydroxyl group in ethanol is directly proportional to the concentration. This was also found by Ouellette et al for cyclohexanol in CCl4. The present author has extended this work to disubstituted cyclohexanol systems like trans-2-aminocyclohexanol, and the methylcyclohexanol isomers, in CCl4 or CDCl3 depending on the solubility of the solutes. The chemical shift at infinite dilution has been found to give an indication of an intramolecular hydrogen bond and the chemical slope to give a measure of the strength of the interrnolecular H bond.
The effect of a lanthanide shift reagent on cyclohexanol, cyclohexylamineand the methyl cyclohexanols was looked at in a quantitative way.
Carbon-13 T1 values were determined for the methy!cyclohexanol isomers by Inversion Recovery Method and the results were compared with the Freeman-Hill Method. 13C or : 1H T1 values were used to give an estimate of the strength of intermolecular hydrogen bonding in the methylcyclohexanols.
The axial and equatorial chemical shifts of the proton of cyclohexanol and the methylcyclohexanol isomers were measured at around 190 K and also the position of resonance at 300 K.
|Date of Award||Apr 1986|