Q35e E - Organic Chemistry (Mcmurry)

Question

Question: At what approximate positions might the following compounds show IR absorptions?

(e)

Step-by-Step Solution

Answer

(e) Absorption of ketone next to aromatic ring at 1690, and aromatic ring at 3030.

Step-by-step Solution Step 1:IR absorption

In general, IR absorption iscaused 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 the functional group are bound by covalent bonds with one another and with rest of the molecule.

The functional group in compound (e) areketone (C=O) next to aromatic ring

Step 3: Position at which compound show IR absorptions

Given compound

(e) Absorption of ester at 1735, ketone next to aromatic ring at 1690, and aromatic ring at 3030.