Steam Distillation

Introduction

The purpose of this experiment is to extract Eugenol from Cloves using steam distillation as a purification technique and to transfer Eugenol from the aqueous phase to the MeCl2 phase. With steam distillation, the boiling point of a mixture of immiscible liquids is lower than the boiling points of the individual components. Water from the steam is one of the components of an immiscible liquid mixture. The vapor pressures of each of the components during the distillation are additive. And, the outcome is a co-distilled mixture of water and immiscible components.

The organic components can be separated from water.

Experimental

First we set up an apparatus for a direct method steam distillation, using a 500 mL three-necked round-bottomed flask. A 125 mL Erlenmeyer flask was used as a collection flask. Placed 7 g of clove buds/ground cloves into the flask and added 150 mL water. Began heating with a Bunsen burner to create a steady rate of distillation. While distilling, we continued to add water from the addition funnel, as needed, to maintain the level of the liquid in the distilling flask.

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Continued until 75 mL was collected.

Chilled. Emptied the water from the addition funnel and placed the chilled distillate in it. Extract the distillate twice with 10 mL portions of CH2Cl2. Poured the Ch2Cl2 into the steam distillate, then gently swirled. Each time, filtered the lower layer through a small amount of anhydrous Na2SO4 into a single tared 50 mL Erlenmeyer flask with 1 boiling chip. Evaporated the solvent using a steam cone in the hood.

Dried the outside of the flask and weighed. Calculated the weight-percent recovery of the oil from the original amount of cloves used. Then, we determined the infrared spectrum of the oil.

• Results, Data, Calculations
• Weight of empty boiling flask: 32.022g
• Weight of flask with oil: 33.651g
• Eugenol oil: 1.632g
• Watch glass weight: 50.288g
• Cloves: 7.011g
• % of Crude Eugenol Isolated: 1.632 x 100 / 7.011g = 23.28%

Discussion of Results

Steam distillation of cloves produced 1.632g of an oil that contained an –OH at 3516.91 cm-1, a C-H at 2937.59 cm-1, and a C=O at 1605.50 cm-1. (The IR spectrum is attached). These are contained in Eugenol. The product from the steam distillation of cloves corresponds closely to the sample of Eugenol as said in the manual. Therefore, the oil isolated was Eugenol. 1.632g of eugenol was extracted from 7.011g of cloves. This gave us a percent recovery of 23.28% (as showed above in calculations).

Expected is 10%, so our recovery is quite high. Possible reasons for this may be due to the use of a smaller Bunsen burner, which created a lower flame, forcing us to let the mixture boil at a longer period of time. Boiling the mixture for such a long time could have extracted more out of the cloves. Also, the cloves were supposed to be grinded, but our grinded cloves had several large chunks that would not grind. Those that did not grind could have had more oil in them compared to the crushed ones. The process of grinding the cloves could have lost some oils as well. Otherwise, from 7.011g of cloves we have recovered about 23.38% eugenol oil.

Conclusion

In this experiment, it was shown that about 23.38% of eugenol oil could be recovered from cloves by steam distillation. The oil was identified as Eugenol by comparison of its infrared spectrum with an authentic sample.

References

1. Infrared Spectroscopy notes, Dr. Etoga. March 5, 2012, Chem 234 class Mondays Chemistry 234 San Francisco State University Chemistry Manual 2012