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Can someone decipher this for me?

  1. May 18, 2010 #1
    Hi,

    I am an electrical engineer, but I have to complete the following procedure:


    Synthesis of Esters. (a)

    Methyl Ester.
    The methyl ester of 10-
    undecylenic acid was prepared similarly to the method used by Sieval.
    The 10-undecylenic acid was dissolved in methanol and allowed to
    reflux for 3 h with a small amount of sulfuric acid. Excess methanol
    was removed by vacuum. The crude product was dissolved in ether,
    washed with a saturated sodium bicarbonate solution, water, then a
    saturated NaCl solution, and dried over magnesium sulfate. The identity
    of the vacuum distilled product was confirmed using proton NMR.
    1H NMR: ä 5.73-5.89 (m, 1H), 4.89-5.04 (m, 2H), 3.67 (s, 3H),
    2.25-2.35 (t, 2H), 1.99-2.09 (m, 2H), 1.54-1.69 (m, 2H), 1.23-
    1.44 (m, 10H).

    (b) 2,2,2-Trifluoroethyl Ester. The fluorinated ethyl ester of 10-
    undecylenic acid was prepared similarly to the methyl ester. To 30 g
    of 10-undecylenic acid was added 22 g of 2,2,2-trifluoroethanol
    dissolved in 40 mL of toluene. This mixture was allowed to reflux
    with a small amount of sulfuric acid for 3 h using a Dean-Stark
    apparatus. Workup similar to the methyl ester produced a crude product
    that was further purified by vacuum distillation. Proton, COSY, and
    fluorine NMR confirmed the identity of the product.
    1H NMR: ä 5.70-5.90 (m, 1H), 4.86-5.06 (m, 2H), 4.38-4.51
    (q, 2H), 2.35-2.45 (t, 2H), 1.98-2.10 (m, 2H), 1.55-1.75 (m, 2H),
    1.20-1.50 (m, 10H). Fluorine NMR: single triplet.


    That word there, WORKUP, is kinda ambiguous to me as an EE. Not sure what part of procedure a.) they are referring to. My best guess is "...washed with a saturated sodium bicarbonate solution, water, then a saturated NaCl solution, and dried over magnesium sulfate."

    Any ideas?
     
  2. jcsd
  3. May 18, 2010 #2
    Looks like a standard transesterification. Workup is everything after the reaction is completed to isolate the desired product. Therefore, according to what you have, the workup is... "The crude product was dissolved in ether (the trifluoroester may or may not be soluble in ether), washed with a saturated sodium bicarbonate solution, water, then a saturated NaCl solution, and dried over magnesium sulfate. The identity of the vacuum distilled product was confirmed using proton NMR."
     
    Last edited: May 18, 2010
  4. May 25, 2010 #3
    Thanks for your help!!
     
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