CHEM 51LC SPRING 2013: EXPERIMENT 1
Isolation of Eugenol from Cloves
TECHNIQUE: Steam Distillation
Steam distillation is used to isolate organic compounds that are immiscible liquids with water
and have reasonably high vapor pressure at the boiling water temperature. This week we will
use steam distillation to isolate clove oil (eugenol) from cloves and determine how effective the
technique is.
READING ASSIGNMENT:
Read Technique 13.6: Steam Distillation pgs 164-166.
(Section 11.7 pgs 153-156 in the 2nd Ed.)
● Review Extraction techniques
●
PRE-LAB ASSIGNMENT:
● Complete all portions of pre-lab notebook work according to guidelines
● Rewrite the STEAM DISTILLATION procedure in your own words!
● Make a flowchart in your notebook for the distillation and the extraction (the alternative
procedure for isolating eugenol).
● Sapling assignment
IMPORTANT SAFETY INFORMATION
Eugenol is an irritant. Avoid all contact with skin and eyes.
Dichloromethane is toxic, an irritant, absorbed through the skin, and harmful if swallowed.
Wear gloves and wash your hands thoroughly after handling it. Avoid contact with skin and
eyes. Dichloromethane is a suspected carcinogen when inhaled in large quantities.
Experimental Procedure:
Obtain an experiment kit from the stockroom.
Weigh out approximately 5.0 g of cloves (record the exact mass) and transfer them into your
round bottom flask. Add 50 mL of distilled water and a boiling chip. Have your TA check your
distillation apparatus before you start distilling! Place your roundbottom directly into a heating
mantle and carefully heat to boil the solution. Make sure your heating mantle is plugged into a
variac, not directly into the wall. Collect ~30 mL of distillate in a 50 mL graduated cylinder.
After the distillation is complete, place the graduated cylinder in an ice bath to ensure complete
separation between the clove oil and the water. Carefully remove the layer of oil from the
graduated cylinder with a pipette and transfer it to a 5 mL Erlenmeyer flask. Try to remove any
accidentally transferred droplets of water from the Erlenmeyer flask using a pipette, and then add
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drying agent to the oil to remove any traces of remaining water. Using a glass pipette with a
cotton ball inside it, filter the oil into a tared vial. Determine the mass of eugenol you isolated.
Add a small amount of acetone to a 10 mL Erlenmeyer flask. Using a spatula, remove a
small amount of your eugenol and dissolve the eugenol on the spatula in the acetone. Take a
TLC of this solution and a standard solution of eugenol in a 5% ethyl acetate/hexanes solvent
system and visualize using a UV lamp. Submit a properly labeled vial containing the eugenol
you isolated to your TA.
Your TA will take a 1H NMR spectra of eugenol your class isolated. You will also be sent
a H NMR spectra of pure eugenol.
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Alternative procedure for isolation of eugenol: If the eugenol does not separate from water
after cooling, extract the aqueous layer with two 10 mL portions of dichloromethane. Combine
the organic layers and dry them with sodium sulfate until the liquid is clear and the drying agent
is not clumpy. Carefully transfer the organic layer into an Erlenmeyer flask, making sure the
solid stays behind. Using mild heat evaporate most of the dichloromethane until you have ~5 mL.
Transfer that into a tared vial and evaporate the rest of the dichloromethane. Weigh the amount
of eugenol you isolated, cap it, and submit it to your TA in a properly labeled vial.
NOTES FOR WRITING YOUR REPORT:
Write a complete lab report as described in the Report Guidelines for Students handout. Include
all of your results. The following guidelines are merely recommendations of things to cover, not
the limits.
Your theory section should include:
● Explain how steam distillation works and what principles allow us to distill clove oil
(boiling point of 254 °C) at a little under 100 °C.
Your results section should include:
● Report the mass of product isolated.
● Cloves are approximately 17% eugenol by weight. Calculate the theoretical mass of
eugenol that can be recovered from the cloves you weighed and % recovery.
● Show all work to receive credit. Calculations can be shown in an appendix or on an
attached sheet.
Your discussion section should include:
● Is steam distillation an effective way to extract eugenol from cloves?
● Discuss the purity of your eugenol. Did you isolate one compound or a mixture?
How did you determine this?
● In broad terms, discuss how large a component of the mixture eugenol is.
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