Oxidation of Cyclododecanol to Cyclododecanone

The determination of the oxidation state of a carbon atom can be used to find a change in the oxidation state. The rules used assign carbon a formal oxidation state based on +1 for any atom less electronegative than carbon, -1 for atoms more electronegative, and 0 for C-C bonds. The carbon must bear an oxidation number that makes this sum equal zero. Increasing the oxidation state or oxidation number of the carbon atom is called an oxidation reaction. This is done in two ways: 1) Increasing the number of carbon-O bonds (or any more electronegative atom than C).

2) Decrease number of C-H bonds.

Aldehydes and ketones can be synthesized by the oxidation of primary or secondary alcohols.

Discussion & Conclusion:

The first part of this experiment examined oxidation reaction which was used to synthesize ketone which is cyclododecanone from secondary alcohol called cyclododecanol using an oxidizing agent called sodium hypochloride. The second part of this experiment recrystallized the cyclododecanone by evaporate ether. Diethyl ether was supposed to evaporate by letting it stay open overnight.

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Since time wasn’t enough, the ether was dried by air and then recrystallized by pouring methanol on it. The solution was let cool in ice water then using vacuum filtration to obtain the final product. Although the obtained product was white like powder, the identity of the product couldn’t be confirmed as cyclododecanone yet. Letting the obtained product stay open on the watch glass overnight to make sure all methanol evaporated.

Following the third part was infrared spectroscopy and melting point to characterize the obtained product.

Due to the melting point range of cyclododecanone, 57.5℃ -59.3℃, compared to the literature value (59-61℃) was close. Upon analysis of the obtained infrared spectrum (credit to Kai Liu), it was found that no signal appeared at 3580-3620 cm-1. This indicates that an –OH group not present in the product. In addition, the IR spectroscopy result showed that there was a signal appeared at 1709 cm-1, indicating the functional group ketone C=O present in the product so it can be stated that the obtained product was indeed pure cyclododecanol. The oxidation of cyclododecanol to cyclododecanone was successful.

The percent yield of this experiment was 23.78 %. This low yield is the result of losing product during the crystallization process. When adding the methanol to dissolve the crude product in the 50 ml Erlenmeyer flask then heated it up. After being dissolved, the mixture sat at room temperature for about 5 minutes and then was submersed in an ice-water bath for another 10 minutes for crystallization to occur. But not much of crystal was obtained through vacuum filtration then let it dry naturally. The mass of pure cyclododecanone crystal was weighted and that value is less than it should be because some of the impure crystal was left in the beaker with methanol and being discarded. This mistake only could be avoided by adding small amount of methanol and should have waited longer so more crystals could be formed.

Work Cited
Gilbert, John and Stephen F. Martin. Experiment Organic Chemistry: A Miniscale & Microscale Approach.
Belmont, CA: Thomson Brooks/Cole, 2010. 537-547. Print
“Table of IR Absorption”. The WebSpectra. UCLA Department of Chemistry and Biochemistry,
22 Jun, 2000. Web. 19 Jan, 2013.