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3.28: Quiz 5B Key

  • Page ID
    19330
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    1. Clearly indicate true (T) or false (F) for the following statements (2 pts each):
    __F__ Transition states are high energy species that have fully formed bonds. (Not fully formed.)
    __F__ A catalyst increases the rate of a reaction by increasing the energy barrier. (Decreasing)
    1. Multiple Choice: (2 pts each)
      1. Select the major product for the reaction of 1-butyne with excess HCl?

        2ia.pngD.png

        2ib.png

      2. Which of the following reactions forms a new C-O bond in the product?
        1. C.pngAlkene reaction with HCl
        2. Alkene reaction with CH3OH without an acid catalyst
        3. Alkene hydration reaction with an acid catalyst
        4. Alkene hydrogenation with a palladium catalyst
      3. Consider the reaction coordinate diagram below and answer the questions (1 pt each):
    2iii.png

    How many transition states are present in the reaction diagram?

    3

    How many intermediates are present in the reaction diagram?

    2

    What species on the diagram is most stable (give a letter)?

    F

    What species on the diagram is least stable (give a letter)?

    B

    Is the overall reaction favorable? (Indicate yes or no) (i.e. exothermic)

    Yes

    1. (8 pts) Label the nucleophile (N) and electrophile (E) in each of the following reaction steps. Then draw the curved arrows to show the flow of electrons and give the structure (intermediate or product) that would result.

    See Special Topic I in Study Guide / Solutions Manual.

    3.png

    1. (7 pts) Draw the curved arrow mechanism and intermediates for the addition of H-Br to an alkene.

    4.png
    See Question #5-1 (and examples in lecture notes)

    1. (8 pts) Indicate (circle) which of the carbocations in the following pair is more stable and briefly explain your answer.
      1. 5a.png

        Both have resonance stabilization. A is a tertiary carbocation and has more carbons directly attached, so it is more stabilized. (The carbon groups are weakly donating compared to just an H.)
      2. 5b.png


        Only A has resonance stabilization. Both are 2° carbocations, and both have an alkene, but only A has the π-bond directly attached for resonance stabilization.
    2. (4 pts) What is the best carbon building block that should be used to synthesize the following alcohol or alkyl bromide?

    6.png

    1. Extra Practice (4 pts): What type of polymerization reaction is used to synthesize polystyrene (Styrofoam)?

    cationic or chain growth

    (some others also acceptable)

    What is the carbon building block (monomer) that is used to synthesize polystyrene? (give structure in the box)

    7.png


    3.28: Quiz 5B Key is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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