Conjugated dienes are chromophores which contribute colors to a compound by light absorption.
The greater the conjugation and resonance, the longer the wavelength absorbed by the compound.
When electrons absorb energy, they transition from a lower energy orbital to a higher energy orbital.
Highest Occupied Molecular Orbital (HOMO) → Lowest Unoccupied Molecular Orbital (LUMO)
Suppose you have two unlabeled flasks, and each flask contains one of these two compounds:
Can you differentiate the compounds using a UV spectrophotometer? Select the true statement.
a. The λmax of the compound with 2 conjugated bonds appears at a longer wavelength than does the λmax of the compound with 3 conjugated bonds.
b. The λmax of the compound with 3 conjugated bonds appears at a longer wavelength than does the λmax of the compound with 2 conjugated bonds.
c. The two compounds cannot be differentiated by their λmax values.
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