Chem 333L Experiment 5 – Oxidation of Cyclohexanol to Cyclohexanone Objectives 1. Oxidize Cyclohexanol to Cyclohexanone using hypochlorite oxidation. 2. Isolate the Cyclohexanone and determine the percent yield. 3. Use 2,4-dinitrophenylhydrazine (2,4-DNP) and determine its melting point. Compare observed melting point with the actual melting point of the derivative Theory 1. General Information a. Oxidation The loss of electrons by atoms, molecules, or ions. The oxidation number increases during oxidation. In organic chemistry, oxidation is defined as an increase in C-O bonds and/or a decrease in C-H bonds. b. Reduction The gain of electrons by atoms, molecules, or ions. The oxidation number decreases during a reduction reaction. In organic chemistry, it is defined as a decrease in C-O bonds and/or an increase in C-H bond. c. Oxidizing agents An oxidizing agent, or oxidant, is a substance that takes electrons in a chemical reaction. The agent is reduced in the process. 2. Reaction a. Reaction Mechanism The oxidant used in this mechanism is elemental chlorine. Also, hypochlorous acid (HOCl) must be present in order to generate the good leaving group, H2O. This reaction mechanism may form an intermediate alkyl hypochlorite ester and after the elimination of hydrogen, a ketone and a chloride ion will be formed. Though the true mechanism is not known for sure, the mechanism below is the most likely. It proceeds faster in an acidic environment than it does in a base. An illustration of the mechanism can be seen in the “Mechanism” section of this report. b. Preparing a derivative of a ketone The purpose of making a derivative is to identify the presence of a carbonyl group. Because most ketones are liquids at room temperature, a melting point cannot be used to determine their identity. The reagent 2,4-DNP reacts with the ketone to form a solid derivative of the it, which can then yield a melting point. The melting point for the 2-4DNP derivative of Cyclohexanone is 162 degrees C. 3. Reasons for addition of sodium bisulfite, sodium hydroxide, and sodium chloride• Sodium bisulfite consumes excess oxidizing agent (hypochlorite). It reacts with and destroys the chlorine generated as a by-product in the reaction. • Sodium hydroxide neutralizes the acidic solution. • Sodium chloride is used to extract the cyclohexanone. The sodium chloride is dissolved in the aqueous layer, which decreases the solubility of cyclohexanone such that I can be extracted completely from this layer and into the ether layer. This process is known as salting out. 4. Green Chemistry Also known as sustainable chemistry is the design of chemical products and processes that reduce or eliminate the use of generation of hazardous substances. Green chemistry applies across the life cycle of a chemical product, including its design, manufacture, and use. MechanismProcedure 1. Add 0.17 mL cyclohexanol, 0.10 mL acetic acid, and 2.3 mL of NaOCl into a small test tube. 2. Cover the test tube with a stopper and agitate it for 3 minutes, venting frequently. 3. After the 3 minute, remove the test tube stopper and place the tube in a warm water bath, for 15 minutes. 4. Add 3 drops of sodium bisulfite, 0.4 mL of 6M NaOH and stir thoroughly. 5. Add 0.15g of NaCl, cover with a stopper and shake until most of the salt dissolves. 6. Add 0.4mL Ether. 7. Collect and keep the top layer. Add this to a pre-weighed test tube. 8. Repeat steps 8 and 9, placing the extracted upper layer in the same pre-weighed tube. 9. Evaporate off the ether using the Steam bath. 10. Obtain the mass and percent yield of the liquid product. 11. Set aside about half of your product for IR analysis. 12. Prepare the 2,4-DNP derivative of the product (cyclohexanone). a. Add 1 drop 2,4 DNP for every 0.01 grams of cyclohexanone being converted in a small, dry test tube. b. Gently heat the mixture in the heating mantle for approximately 1 minute. c. Collect and dry the derivative via suction filtration. 13. Determine the melting point of the derivative and compare wth the actual or theoretical melting point (162 C). ApparatusReagent Table Name, Structure, MW (g/mol) Melting C Boiling C Density g/mL Properties Acetic Acid CH3COOH 60.05 16.2 117-118 1.049 Corrosive material. Colorless liquid or solid with a strong vinegar-like odor Sodium Chloride NaCl 58.44 801 1413 2.165 White crystals. Hygroscopic. Sodium Bisulfite NaHSO3 150 - 1.48 Usually present as a mixture of sodium bisulfite and sodium meta-bisulfite Sodium Hypochlorite NaOCl 74.44 -6 40 1.206 Light sensitive. Corrosive. Sodium Hydroxide NaOH 39.99707 318 1390 2.13 Corrosive material. Colorless, odorless solid. 2,4-DNP C6H6N4O4 198.13 198 - - Flammable liquid, orange crystals with ammonia-like odor Cyclohexanol C6H11OH 100.16 20-22 161 0.948 Colorless, viscous liquid or sticky solid with a faint camphor odor. Hygroscopic. Diethyl Ether C4H10O 74.12 -116.3 34.6 0.7134 Colorless liquid with a characteristic, sweet, ether odor. Cyclohexanone C6H10O 98.14 -47 155 0.947 Disposal • Wash excess aqueous solutions down the drain with water. • Dispose of the 2,4 DNP filtrate liquids and other organic solvents in the liquid waste container and the solid waste in the solid waste container. • Dispose of soiled gloves, paper towels, and broken glass in the appropriate containers. References Chemistry 333L&334L: Microscale Experiments in Organic Chemistry Organic Chemistry 10th