Question

1. What is the purpose of using copper sponge in a fractionating column?

3. Name two places on the distillation apparatus that when clamped may cause a gap between connecting joints.

How can IR spectroscopy be used to distinguish between an ester and a ketone?

Answer 1

1) The purpose of distillation is to separate two or more mixed liquids with respect to their volatility. Now, making column requires effective surface area for condensation. More the effective surface area of condensation , more is effective separation. So , we use copper sponge to increase the surface area of condensation which alternatively makes more efficient separation.

2) a) in the connection point of vacuum adaptor, a gap is retained

b) at the thermometer adaptor.

3) The functional differences between an ester and a ketone is that in case of ester , there is a -OR group attached with the carbonyl group where in case of carbonyl group , there is no -OR moiety present , rather a -R group is present.

The C=O frequency for aliphatic ester is near about 1750-1735 cm^-1 whereas , for ketone it is 1725 cm^-1.This is due to the fact that , due to presence of an electronegative atom oxygen , which has much more effective '-I ' effect shifts the stretching frequency of carbonyl group to higher range than that of ketone.