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Multiple Choice
Using the Woodward-Fieser Rules, determine the λmax for the following compound.
A
239 nm
B
326 nm
C
390 nm
D
268 nm
E
235 nm
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Verified step by step guidance
1
Identify the base structure of the compound. In this case, the compound is a bicyclic diene system, which is a type of conjugated diene.
Apply the Woodward-Fieser rules for conjugated dienes. The base value for an acyclic diene is 214 nm. For a homoannular diene, the base value is 253 nm.
Count the number of alkyl substituents and exocyclic double bonds. Each alkyl substituent adds 5 nm, and each exocyclic double bond adds 5 nm to the base value.
Identify any additional conjugation or auxochromes that might affect the λmax. In this structure, consider the effect of the bicyclic system and any additional conjugation.
Sum the contributions from the base value, substituents, and any other factors to estimate the λmax for the compound. Compare this calculated value to the given options to determine the most likely λmax.