Question

What is the reaction product(s) of oleic acid & sodium methoxide? Show the structure(s).

Part A: Acid Catalyzed Fischer Esterification of Free Fatty Acids

1. Add 20 mL of canola oil and a magnetic stir bar to a 125-mL Erlenmeyer flask, and place the flask on a magnetic stirring plate. Add 2–3 mL of methanol and up to three drops of concentrated sulfuric acid
   1. Perform this step with caution, as this is a strong acid!
2. Immerse a thermometer into the reaction mix, and stir the reaction vigorously for 15–20 minutes with the magnetic stir bar. Provide additional heating using the hot plate to maintain the reaction temperature between 40 and 60 °C. In addition to the magnetic stirring, occasionally swirl the contents manually to return condensates from the walls of the flask to the reaction mix.

Part B: Base Catalyzed Transesterification of Triglycerides

1. Crush 0.75–1.0 g of sodium hydroxide pellets in a mortar and pestle, and add to the reaction mixture in the Erlenmeyer flask.
   1. Perform this step with caution, as this is a strong base!
2. Add 7–8 mL of methanol. Alternately, if time permits, the NaOH may be predissolved in methanol in a separate container and the resulting solution added to the reaction mixture for improved yields.
   1. Please see the instructor for clarification as to which method is preferred for the addition.
3. Continue stirring for 30 minutes at 40–60 °C. Provide additional heating using the hot plate maintaining the reaction temperature. In addition to the magnetic stirring, occasionally swirl the contents manually to return condensates from the walls of the flask to the reaction mix.

Part C: Isolation of Product

1. While the reaction mix is still warm, remove the magnetic stir bar and decant the liquid contents into a separatory funnel. The layers will slowly separate. Slowly and carefully drain out the thick lower layer and discard into waste. If there is no separation, do not drain anything from the separatory funnel and proceed to Step 2.
2. Add 10 mL of water to the remaining top layer in the separatory funnel. Stopper and shake the separatory funnel. The layers will form an emulsion.
3. Drain the resulting emulsion into centrifuge tube(s) and centrifuge at 2000 rpm for 2 minutes. The liquid top layer will be the reaction product, biodiesel, and is most easily removed with a Pasteur pipet. The lower layer may be discarded into waste and the centrifuge tube(s) cleaned using soap and water for reuse.
4. Repeat the water/biodiesel organic layer wash in a clean separatory funnel followed by centrifugation to isolate the final product. If separation does not occur, a small amount of sodium chloride (NaCl) may be added to the centrifuge tube, the contents shaken/inverted, and the sample recentrifuged to produce two layers.
5. Combine the top layer(s) of biodiesel product into a clean, dry test tube, and obtain a mass of the final product to record in the laboratory notebook.

Part D: Chromatographic and Spectral Data

1. Acquire Fourier transform infrared (FTIR) spectra of the starting material cooking oil and the lab synthesized reaction product, biodiesel.
2. Compare the starting material cooking oil, reference standard of biodiesel and the reaction product by thin layer chromatography (TLC; silica plates with 9:1 hexane:ether as eluent followed by visualization using I₂ vapor).
3. See the instructor for further directions regarding the spectral data.

Answer 1

The oli hatic etes of oleic oid eads uadh Sadium medhond do doom medhgl etezs In dhis cate oleic od ms methyl ol eote as OA CH30NQ (sodtum methontde) (oleic aad COOCH3 Cmethyl oleab)