Question

Attached is the lab experiment. Here are the questions I need help with:

1. What is the purpose of each of the following steps in this experiment?

a. Adding solid NaCl to the reaction mixture

b. Repeated washings with water, sat'd NAHCO3, and brine

c. the pipet column chromatography

2. Which compound, cyclohexanol or cyclohexanone will have a higher Rf on a TLC plate?

3. What is the advantage of using sodium hypochlorite as an oxidant over CrO3 or Na2Cr2O7 for oxidation?

4. In this reaction, which species is the oxidant and which the reductant?

PROCEDURE OXIDATION OF CYCLOHEXANOL TO CYCLOHEXANONE Set up a water bath as the heat source to warm the reaction mixture on a stirrer/ hotplate. Use a 125-mL beaker for the water bath and place it directly on the surface of the hotplate (no need for a sand bath). The oxidant is significantly unstable above 50 °C, so careful temperature control is necessary. 1. To your 5-mL long-necked round-bottomed flask, add 0.150 g of cyclohexa- nol, 0.3 mL of glacial (!!) acetic acid (CH COOH), and 1.0 mL of acetone. 2. Add a magnetic stir bar. 3. Using the black Viton connector, attach an air condenser to the flask and clamp the assembly to a laboratory stand. Wrap the air condenser with a moist paper towel. 4. Immerse the flask in a water bath heated to 45 °C. (Do not go significantly above this temperature.) Start the stirplate at a medium setting. 5. Over the course of 30 minutes add a total of 6 mL of sodium hypochlorite solution (6% aqueous NaOCI, Ultra Clorox) while maintaining stirring and heating for 30 minutes. Addition of 1 mL every 5 minutes is a good pace. (More frequent addition of smaller volumes is better than less frequent addi- tion of larger volumes.) 6. After the last addition continue stirring for 15 minutes. 7. Quench excess oxidant by the dropwise addition of saturated aqueous sodium bisulfite-test with starch-iodide paper and add more sodium bi- sulfite until the starch iodide paper no longer changes color (white blue). (Test your starch iodide paper with bleach first so that you know what kind of color change you are looking for.) 10 ORGANIC CHEMISTRY 272L

Answer 1

Question 2.

Cyclohexanone will have a higher R_f on a TLC plate because it's less polar than cyclohexanol.

Question 3.

Sodium hypochlorite (NaClO) is a much milder oxidant as compared to CrO3 or Na2Cr2O7.

Question 4.

Cyclohexanol is the reductant, whereas the cyclohexanone is the oxidant.