Question

Which of the following compounds has the longest λ max ? https://www.chegg.com/homework-help/questions-and-answers/following-compound-s-longest-max-q3760297

Answer 1

Option (`I`).

Explanation:

The first one (`I`) has the longest `lambda_max` because it has the longest conjugated system made out of 4 double bonds (two double bonds from the substituent and two in the ring).

A conjugated system is characterized by the alternation of double-single bonds. Every two double bonds are separated by one single bond.

The longer the conjugated system in molecules the higher their capability of interacting with light and absorbing light.