16. Conjugated Systems

For the following terpenes, identify the isoprene units. In cross-linked or ring-containing terpenes, linkages can be formed between more than just C₁ and C₄ of isoprene

(c)

Vitamin E, especially the B ring and the side chain, is a terpenoid derivative. Identify the isoprene units nature used to make it.

At pH = 7, one of the ions shown here is purple and the other is blue. Which is which?

Which of the following species is conjugated?

Which of the following is not true of conjugation in organic molecules?

Why does conjugation between an $H_{\mathrm{fr}}$ strain and an $F^{-}$ strain not result in two $H_{\mathrm{fr}}$ strains?

Which of the following molecules is capable of conjugation?

Which statement about conjugation is false?

Which of the following statements about conjugation is true?

Answer the following questions for the molecular orbitals (MOs) of 1,3,5,7-octatetraene:

d. Which MO is the HOMO and which is the LUMO in the ground state?

Identify the isoprene units in the terpenes shown. In cross-linked or ring-containing terpenes, linkages can be formed between more than just C₁ and C₄ of isoprene.

(b)

How can you use UV spectroscopy to distinguish between the compounds in each of the following pairs?

b.

Answer the following questions for the molecular orbitals (MOs) of 1,3,5,7-octatetraene:

c. Which MOs are symmetric, and which are antisymmetric?

Which of the following statements regarding conjugation is true?

Answer the following questions for the molecular orbitals (MOs) of 1,3,5,7-octatetraene:

e. Which MO is the HOMO and which is the LUMO in the excited state?