Friday, October 18, 2019

The Green Oxidation of Cyclohexanol to Cyclohexanone Lab Report

The Green Oxidation of Cyclohexanol to Cyclohexanone - Lab Report Example KMnO4 and Cr (VI) compounds such as H2CrO4 have been widely used as oxidizing agents in the oxidation of alcohols to carbonyl compounds. However, each of these two reagents has its disadvantages, and chemists are increasingly using reagents containing chlorine in a positive oxidation state such as hypochlorite compounds. Sodium hypochlorite is the reagent chemists most commonly use for this purpose. Sodium hypochlorite has three crucial advantages over Cr (VI) compounds when used to oxidize cyclohexanol to cyclohexanone. Firstly, it has no hazardous waste products in contrast to Cr (VI) oxidations, which yield Cr (III) compounds, which are toxic to aquatic life. Secondly, sodium hypochlorite and its products have no skin or membrane irritation effects other than a negligible amount of chlorine gas, in contrast to Cr (VI) compounds, which are skin and membrane irritants. Thirdly, hypochlorite reagents are considerably cheaper than Cr (VI) compounds (Baird & Cann, 2008, p.67). 8 ml of cyclohexanol and 4 ml of glacial acetic acid were added to a 250 ml Erlenmeyer flask. A thermometer was placed into the flask and used to record the initial temperature. 115 ml of commercial bleach (NaOCl) was obtained in a beaker. The bleach was slowly added to the Erlenmeyer flask using a disposable pipette while slowly stirring the flask. The temperature was maintained between 40oC and 50o using an ice water bath large enough to hold the flask. After adding all the bleach, the mixture was allowed to sit for about 20 minutes. The mixture was continuously stirred during this period. The presence of the oxidizing agent was tested by adding a drop of the solution to a piece of starch-iodide paper. There was no color change indicating that hypochlorite was not present. 4 drops of thymol blue indicator were added to the reaction mixture. The solution turned yellow. 18.4 ml of 6 M sodium hydroxide was added to the reaction mixture until a neutral pH was obtained. This point was indicated by a color change to blue. A simple distillation apparatus was set up, with the receiving container being a 50 ml graduated cylinder. A 250 ml round-bottomed flask was used as the â€Å"still pot†. The mixture was distilled through steam distillation, and a mixture of cyclohexanone and water was obtained in a graduated cylinder. 40 ml of distillate was obtained. B. Isolation and Purification of Cyclohexanone The distillate mixture was placed in an Erlenmeyer flask. 6.8 g of NaCl was slowly added to the 34 ml aqueous layer with stirring in order to reduce the solubility of the cyclohexanone. This enabled it to be extracted completely using ether. The mixture was poured into a separatory funnel. Ether was added to the mixture until a 20 – 25 ml of organic layer was obtained. The separatory funnel was gently shaken with frequent venting. The aqueous and organic layers were left to separate. The aqueous layer was run off into a beaker labeled â€Å"aqueous waste†. The ether solution was poured from the separatory funnel into an Erlenmeyer flask. 3 M sodium hydroxide solution was added to the solution of ether, and the flask was gently shaken with frequent venting. The resulting aqueous layer was

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