Which one of the following compounds will have the lowest wavenumber for carbonyl absorption?

Question

Quizplus · Accepted Answer

The wavenumber for carbonyl absorption is influenced by the electron density surrounding the carbonyl group. In compounds I, IV, and V, there are additional electron-withdrawing substituents (chloro, nitro, and cyano groups respectively) that decrease the electron density, leading to a higher wavenumber. In compounds II and III, there are only alkyl groups attached to the carbonyl group, but in compound III, the alkyl group is more bulky (tert-butyl) compared to compound II (methyl), leading to a greater steric hindrance and a lower electron density, resulting in a lower wavenumber. Therefore, compound III has the lowest wavenumber for carbonyl absorption.

Which One of the Following Compounds Will Have the Lowest