Chapter 20, Problem 20.23P

Interpretation Introduction

Interpretation:

How 1,3-cyclohexadiene and 1,4-cyclohexadiene are distinguished by $\text{UV-}$ spectroscopy has to be shown.

Concept Introduction:

$UV-$ spectroscopy in characterizing conjugation:

• • $\text{UV-}$ spectroscopy is the technique that is widely used to characterize a compound via conjugation.
• • Conjugation between double bonds in a compound decreases the energy gap between filled and unfilled $\text{π}$-orbitals.
• • The smaller energy gap absorbs longer wavelength of ultraviolet radiation and effectively promotes the ${\text{π-π}}^{\text{*}}$ transition.
• • The longer wavelength of $\text{UV-}$ radiation can be easily observed in $\text{UV-}$ spectroscopy which corresponds to the particular ${\text{π-π}}^{\text{*}}$ transition of conjugation.
• • By this way, $\text{UV-}$ spectroscopy characterizes a compound with conjugation.