Topic 5 - Aromaticity and Aromatic Substitution

Problem Set Due 16 November

  1. Read Chapters 8 and 9 in Carey and Sundberg

  2. Read the Web page on alternant and nonalternant hydrocarbons

  3. Do any seven of the following problems:

  4. Choose one problem from among Carey/Sundberg: 8.4, 8.7, 8.16

  5. Classify the species below as alternant or non alternant; if alternant, further classify as odd or even.

    Comment on the expected charge distribution in these molecules. Then do a Huckel MO calculation on each. Are your expectations verified?

  6. Using perturbation MO theory, analyze the addition of a single carbon with a p orbital to allyl to yield either butadiene or cyclobutadiene. Show that the interaction is stabilzing in one case and not in the other.

  7. Now use the Huckel MO program to analyze the same systems. Comment on your results.

  8. Which of the species shown below are aromatic? Why or why not? Can a simple structural or chemical change make aromatic those that aren't?

  9. Design aromatic species that fit the following descriptions. If no such species can be designed in a particular case, explain why not.

    • Contains one boron and one oxygen in a six-membered ring

    • Contains one oxygen and one nitrogen in a neutral six-membered ring

    • Contains a boron and a nitrogen in a five-membered ring

    • Contains a twelve-membered carbocyclic ring

    • Contains a 14-membered ring with two trans- double bonds

  10. Carey and Sundberg, Problem 9.7.

  11. Carey and Sundberg, Problem 9.13.

  12. Predict the principal product from monobromination of each compound below, and explain your reasoning:

  13. Write mechanisms for each of the following reactions:

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