Exam 15: Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy

UV spectroscopy measures the energy required to promote an electron from the ________ molecular orbital to the ________ molecular orbital.

Why does the (E,E)-isomer of 2,4-hexadiene react much more rapidly with dienophiles than does the (Z,Z)-isomer?

Three halogenated organic products result from the reaction below. Draw the structure of each product and then circle the most stable product.

How many nodes, other than the node coincident with the molecular plane, are found in the highest energy π MO of 1,3-butadiene?

What reagent could be used to convert allyl tosylate directly into oct-1-ene?

Provide a picture of the HOMO of 1,3,5-hexatriene.

Give a representation of the bonding π molecular orbital of the allyl anion.

Provide a picture of the LUMO of 1,3,5-hexatriene.

Consider the hydrogenation reaction of each compound listed and rank the compounds in order of increasing ΔH° of this reaction. The most negative ΔH° should be listed first. 2,5-dimethyl-1,3-cycloheptadiene, 1,4-dimethyl-1,3-cycloheptadiene, and 3,6-dimethyl-1,4-cycloheptadiene

Into what is NBS converted as it reacts in allylic bromination reactions?

What are the structures of A, B, and C?

Assuming kinetic conditions, provide the correct stereochemistry and regiochemistry of the major product of the following reaction.

Consider the hydrogenation of each compound listed and rank the compounds in order of increasing ΔH°. The most negative ΔH° should be listed first. cis-pent-2-ene, 2,3-pentadiene, and trans-1,3-pentadiene

Which of the following compounds has the most negative heat of hydrogenation?

Which of the following represents the highest occupied molecular orbital for the conjugated pi system in Vitamin D3?

For what does the acronym HOMO stand?

Given that 1,3-butadiene has a uv absorption of 217nm, predict the approximate absorption for the conjugated system in vitamin D₃.

When 1,3-butadiene reacts with CH₂=CHCN, which of the terms below best describes the product mixture?

Give a representation of the antibonding π molecular orbital of the allyl cation.

Provide the major organic product of the following reaction.