Q35d E - Organic Chemistry (Mcmurry)

Question

At what approximate positions might the following compounds show

IR absorptions?

Step-by-Step Solution

Answer

(d) It shows one distinguishing absorption due to ester at 1735 ${\text{cm}}^{-1}$

Step 1:IR absorption

In general, IR absorption are caused by the interaction between the IR electric field vector and molecular dipole transition related to the molecular vibrations. Absorption is at maximum when the electric field vector and dipole transition moment are parallel to each other.

Step 2: Identify the functional group

Functional groups are groups of one or more atoms with distinctive chemical properties regardless of what is attached to them.

The atoms of functional group are bound by covalent bonds with one another and with rest of the molecule.

The functional group in compound (d) is ester only.

Step 3: Position at which compound show IR absorptions

(c)

(d) Absorption of ester at 1735 ${\text{cm}}^{-1}$

It shows one distinguishing absorption due to ester at 1735 ${\text{cm}}^{-1}$