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Biphenyl has the following structure.(a) Is biphenyl a
Chapter 10, Problem 40SP(choose chapter or problem)
Biphenyl has the following structure.
(a) Is biphenyl a (fused) polynuclear aromatic hydrocarbon?
(b) How many pi electrons are there in the two aromatic rings of biphenyl? How does this number compare with that for naphthalene?
(c) The heat of hydrogenation for biphenyl is about \(418 \mathrm{kj} / \mathrm{mol}\) (100 kcal/mol). Calculate the resonance energy of biphenyl.
(d) Compare the resonance energy of biphenyl with that of naphthalene and with that of two benzene rings. Explain the difference in the resonance energies of naphthalene and biphenyl.
Equation transcription:
Text transcription:
418{kj} /{mol}
Questions & Answers
QUESTION:
Biphenyl has the following structure.
(a) Is biphenyl a (fused) polynuclear aromatic hydrocarbon?
(b) How many pi electrons are there in the two aromatic rings of biphenyl? How does this number compare with that for naphthalene?
(c) The heat of hydrogenation for biphenyl is about \(418 \mathrm{kj} / \mathrm{mol}\) (100 kcal/mol). Calculate the resonance energy of biphenyl.
(d) Compare the resonance energy of biphenyl with that of naphthalene and with that of two benzene rings. Explain the difference in the resonance energies of naphthalene and biphenyl.
Equation transcription:
Text transcription:
418{kj} /{mol}
ANSWER:Solution 40SP
(a)
Fused rings share a common - carbon bond and its two carbon atoms. In Biphenyl two Benzene rings share a carbon - carbon bond but not the two carbon atoms. So biphenyl is not a fused polynuclear aromatic hydrocarbon
(b)
Biphenyl has two separate benzene rings. So the total number of pi electrons in biphenyl is 12.
Naphthalene is a fused polynuclear aromatic hydrocarbon. The two benzene rings share a carbon - carbon bond. So the number of pi electrons in naphthalene is 10.