The major constituents of clove oil are eugenol, eugenyl acetate, and caryo- phy
ID: 1004589 • Letter: T
Question
The major constituents of clove oil are eugenol, eugenyl acetate, and caryo- phyllene: The passage below describes how the three compounds can be separated us- ing techniques and materials similar to those employed in this experiment.
Dissolve 1 mL of clove oil in 2 mL of methylene chloride. Add 10 mL of aqueous sodium hydroxide (NaOH) solution. Shake and separate the layers, setting the layer containing the NaOH aside. Obtain a silica-packed chroma- tography column. Add 2 mL of the non-polar solvent hexane to the column, allow the solvent to just reach the top of the silica packing, then immediately add the clove oil/methylene chloride layer that was separated earlier. Allow the organic layer to just reach the top of the silica packing, then immediately add 10 mL more of hexane. When the solvent just reaches the top of the sil- ica packing, switch solvents by adding 10 mL of the moderately polar sol- vent acetone.
(1) Which component of clove oil ends up in the layer containing the NaOH? Explain your answer.
(2) Which component of clove oil is pushed down the column by hexane? Explain your answer.
(3) Which component of clove oil is pushed down the column by acetone? Explain your answer.
Explanation / Answer
Three three components of olive oil in methylene chloride is taken.
Eugenol is an phenol. Phenol tends to react with NaOH and forms sodium phenoxide species which dissolved in water. The water layer is separated. The remaining methylene chloride has eugenyl acetate (polar component) and caryophyllene (non-polar component. Remembering like-dissolves-like, a non-polar fraction (caryophyllene) would prefentially dissolve in a non-polar solvent such as hexane and some come out of column first. The more polar componenent eugenyl acetate ould dissolve in more polar acetone solvent and comes off the column at the end.
Thus,
(1) Eugenol will be in the layer containing NaOH (pl. see details above)
(2) Caryophyllene will be pushed by hexane down the column first (see above for details)
(3) The final component eugenyl acetate will be pushed down by more polar acetone solvent. (pl. see above)
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