The major constituents of clove oil are eugenol, eugenyl acetate and caryophylle
ID: 1015612 • Letter: T
Question
The major constituents of clove oil are eugenol, eugenyl acetate and caryophyllene. The passage below describes how the three compounds can be separated using techniques and materials similar to those employed in an experiment.
Dissolve 1 mL of clove oil in 2 mL of dichloromethane. Add 10 mL of aqueous sodium hydroxide (NaOH) solution. Shake and separate layers, setting the layer containing the NaOH aside. Obtain a silica-packed chromatography column. Add 2 mL of hexane to the column, allow the solvent to just reach the top of the silica packing, then immediately add the dichloromethane 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 silica packing, switch solvents by adding 10 mL of acetone. Switch to acetone.
Which component of clove oil (eugenol, eugenyl acetate, or caryophyllene) ends up in the layer containing the NaOH? Explain your answer.
Which component of clove oil (eugenol, eugenyl acetate, or caryophyllene) is pushed down the column by hexane, a non-polar solvent? Explain your answer
Which component of clove oil (eugenol, eugenyl acetate, or caryophyllene) is pushed down the column by acetone, a moderately polar solvent? Explain your answer.
Explanation / Answer
1) eugenol is separated by NaOH as it has -OH.hydroxyl group, polar that forms -O-Na+ ionic salt and hence dissoves in NaOH and gets separated
2)Caryophyllene is a hydrocarbon.non-polar that is dissolved in non-polar hexane and is separated by column chromatography
3)eugenyl acetate is pushed down the column by acetone, a moderately polar solvent, as eugenyl acetate ( an ester formed when -OH reacts with acetic acid to become -COOEt ) ester functional group is moderately polar.
-C=O of -COOEt is polar as O is more electronegative than C and hence pulls electronic cloud to render C as partially positive and O as partially negative .but this negative inductive effect of -C=O is reduced due to electron donating -OEt attached to it.
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