MS 1657 - Ch 21

MS 1657 - Ch 21

Textbook: McMurry 8th Ed. (2011)

Description: Carboxylic Acid Derivatives

Total Problems: 10

  1. Problem # 724

    Use curved arrows to show the formation of the tetrahedral intermediate of a Fischer esterification reaction (shown below). There are three steps in total.

  2. Problem # 730

    N,N-dimethylformamide (DMF) is shown below. Based on its structure, you might expect to see only one -CH3 signal in the 1H NMR spectrum. But instead DMF shows two different -CH3 signals. Explain.

  3. Problem # 670
     

    Draw out the mechanism for the addition of excess phenyl Grignard to the carbonyl compound below.

  4. Problem # 708

    The overall mechanism for Fischer esterification is shown below. This isn't a real mechanism, just an outline.

    Methanol (the nucleophile) attacks the carbonyl carbon, forming a tetrahedral intermediate, which then loses a water to reform the carbonyl. This mechanism is called nucleophilic acyl substitution.

     

    Use curved arrows to draw a full mechanism for this reaction. I've included structures for you to use as a guide.

    This reaction takes place under acidic conditions, so the mechanism you draw will be similar to those in problem 706.

  5. Problem # 725

    A chemist carried out a Fischer esterification using methanol that was isotopically labeled with 18O (indicated with an asterisk).

    Which one of the esters below (A-D) was formed?

  6. Problem # 726

    Show two esters that would yield the two alcohols below after treatment with lithium aluminum hydride.

  7. Problem # 727

    Show how the ester below can be prepared from propene.

  8. Problem # 728

    The acyl group is a protecting group for amines. Amines can be acylated using acetic anhydride, and deacylated with base.

    Propose a mechanism for each reaction.

  9. Problem # 729

    The ester below was dissolved in a solution of water, a small amount of which was isotopically labeled with O-18, denoted with an asterisk.

    After a few hours, some isotopically labeled oxygen was found in the ester. Where was it found in the ester? Can you explain why?

  10. Problem # 669
     

    In your own words, what is the major difference in the addition of a Grignard reagent to an oxidation state III carbonyl (ester/acid chloride) versus an oxidation state II carbonyl? (aldehyde/ketone)