Oxidation of Cyclododecanol to Cyclododecanone

John Williamson-Chem 341-Section 007

Oxidation of Cyclododecanol to Cyclododecanone

Introduction

The goal for the oxidation of cyclododecanol to cyclododecanone is to demonstrate the oxidation of a secondary alcohol to the corresponding ketone using hypochlorous acid. The oxidation of alcohols plays a key role in the transformation of alcohols into ketones, which have a major role in organic synthesis. Preparing aldehydes and ketones from primary and secondary alcohols is important in order to make certain products. The reaction scheme for the oxidation of cyclododecanol to cyclododecanone is shown in figure 1.1.

Fig 1.1

The mechanism for the oxidation of cyclododecanol to cyclododecanone is shown in figure 1.2.

Fig 1.2

Some new techniques used in this lab included the starch iodide test, and the Fourier transform infrared spectroscopy.

Procedure

To start, 0.5 g of cyclododecanol, 1.2 mL of acetone, and 0.5 mL of glacial acetic acid were placed into a 25-mL round-bottom flask. The mixture was then equipped with a stir bar, and heated to a gentle reflux. Using a Pasteur pipette, 8 mL of commercial bleach (ca. 5.3% sodium hypochlorite) was added drop wise to the mixture, and allowed to stay in a state of reflux for 30 minutes. After the allotted time, the mixture was removed from heat, and the layers were allowed to separate. A portion of the aqueous layer was removed and a couple of drops were placed onto a piece of starch/iodide test paper, to determine if enough hypochlorite was added or not. If the test was positive, the test paper would turn a color of blue-black, if the test was negative; 1mL of bleach was added and allowed to reflux for 20 minutes. Once the starch iodide test showed positive, the mixture was allowed to cool to room temperature, and transferred to a seperatory funnel. The round bottom flask was rinsed with 5 mL of Diethyl ether, and the wash was transferred into the seperatory funnel. The mixture was shaken, and an additional 10 mL of diethyl ether was added for extraction. 5mL of saturated sodium bicarbonate was added to the extract, and swirled until the evolution of CO2 dispersed. The mixture was shaken, with proper venting to relieve any pressure, and the organic solution was washed with 5mL portions of saturated aqueous sodium bisulfate and saturated aqueous sodium chloride. The organic solution was then transferred to an Erlenmeyer flask, and dried over several spatula tips full of anhydrous sodium sulfate. After 10-15 minutes of drying, the dried ethereal solution was transferred into a 25-mL round bottom flask, and equipped to a rotary evaporator. 2 mL of methanol was then added to the crystallized extract in the round bottom flask, and heated and stirred. If the solution was not clear, more methanol was added drop wise until it became clear. The solution was then allowed to cool, and 10 mL of water was added. The solution was placed into an ice bath for 10 minutes, and then