Question

A sample of isoborneol prepared by reduction of camphor was analyzed by IR and showed a band at 1750 cm-1. This result was unexpected. Why?

Answer 1

Doesn't the C=O group absorb about 1750 cm^-1 or so. And doesn't camphor have a C=O group? What surprises me is that it was unexpected. Surely we don't expect 100% yield.

Answer 2

Camphor has a C=O group but isoborneol does not. Just an OH group. I was thinking that it was the C=O absorption that was a result of some camphor not reacting and being left with the product.

Answer 3

Camphor has a carbonyl group which would produce an IR band at 1750 cm^-1. During the reduction, the C=O group would change to C-OH which absorbs IR at a much higher spatial frequency. The reduction might have been incomplete, with enough camphor present to produce the 1750 cm^-1 band.