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

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

Consider the possible thermal [4+4] cycloaddition of two molecules of 1,3-butadiene to generate cycloocta-1,5-diene. Show the HOMO/LUMO interaction which would result, and use this interaction to predict whether the proposed cycloaddition could occur.

Provide the structure of the major organic product in the following reaction.

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

Predict the outcome of the reaction shown below.

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

Show how the carbon p orbitals overlap to form the π₂ molecular orbital of the allyl cation.

Which diene reacts more rapidly in Diels-Alder reactions, cyclopentadiene or 1,3-butadiene? Briefly explain your choice.

Which compound requires a higher energy photon to cause a π to π^* (HOMO/LUMO) transition, 1,3-butadiene or 1,3,5-hexatriene?

Provide the major organic product of the following reaction.

Draw (E)-1,3-hexadiene in its s-cis conformation.

Which compound has the smallest heat of hydrogenation?

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

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

Draw the HOMO of allyl anion.

Draw the HOMO of pentadienyl cation.

The structure of cholesterol is shown below. How many allylic carbons are there in this structure?

Provide the structure of the major organic product in the following reaction.

What descriptive term is applied to the type of diene shown?

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