Cyclohexyl iodide, determination

The case of cyclohexyl iodide provides an example of the use of NMR spectroscopy to determine the conformational equilibrium constant and the value of -AG°. At -80 C, the NMR spectrum shows two distinct peaks in the area of the CHI signal, as shown in Fig. 3.6. The multiplet at higher field is a triplet of triplets with coupling constants of 3.5 and 12 Hz. This pattern is characteristic of a hydrogen in an axial position with two axial-axial couplings and two axial-equatorial couplings. The broader peak at lower field is characteristic of a proton at an equatorial... 

An example of the use of NMR spectroscopy in determining the equilibrium constant between conformers, and therefore the value of -AG°, can be found in the case of cyclohexyl iodide. At —80°C, the NMR spectrum of cyclohexyl iodide is well resolved, and clearly indicates the presence of two conformations (Fig. 3.6). The region of the spectrum shown is for the proton on the carbon atom that bears the... 

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