Isolating Clove Oilfrom Cloves Using Steam Distillation

Definition

Simple & Fractional Distillation: distillation of two miscible liquids.

Raoult’s Law: PPTT = x= x11PP11°° + x+ x22PP22°°

Codistillation: distillation of two immiscible liquids.

Dalton’s Law: PPT T = P= P11ºº + P+ P22ºº

Compounds 1 and 2 start to codistill when PT is equal to atmospheric pressure (760 torr).

Steam Distillation: distillation of water + another liquid.

Pure Water: Pwº = 760 torr at 100 ºC

Advantage: steam distillation allows the mixture of organic liquids to distill below 100 ºC: good for unstable or high boiling point compounds.

Essential Oils

A volatile oil, usually having the characteristic odor or flavor of the plant, frequently is a

water-immiscible liquid separated by distillation from the plant material. Such oils are

used to make perfumes, flavorings, cosmetics, incenses, and medicine.

For exampleFor example: Clove oil consists of several compounds such as eugenol, which is the major component (85-90%) and eugenol acetate (9-10%). Eugenol has a boiling temperature of 254 ºC and can be steam distillated from freshly ground clove.

Steam Distillation Set-Up (Semi-Microscale)

claisenadapter

rubber bands

stopper instead of thermometer

125 mL E. flask

fill with H2O

mark level with marker

500 mL flask with boiling chip Heating mantle supported with lab jack

Changes from the Lab Manual

1. Use 10 grams of powdered cloves/150 mL of water rather than 5

grams of whole cloves/40 mL of water.

2. Use a 500 mL round bottom flask rather than a 100 mL round

bottom flask.

3. Collect 100 mL distillate in a 125 mL E. flask.

4. Use a heating mantle for your heat source rather than a bunsen

burner or a hot plate.

5. Use ether to extract the distillate rather than methylene chloride.

Formation of big bubbles during the distillation will be seen. Powdered cloves may lead to foaming if too much heattoo much heat is applied.

Adding Cloves into the round bottom flask using the stemless funnelstemless funnel

Clove Powder in the Flask

Experimental Procedure

Steam Distillation:

• Don't forget to apply greasegrease at every glass joint.

• Distill at a steady rate: 1 drop/21 drop/2--3 seconds3 seconds (instead of 1 drop/5 seconds).

•• Maintain water levelMaintain water level by adding water from the addition funnel to the marked level.

• Distill until no oily layer is apparent. Collect at least 100 mL of distillate(water + clove oil).

Extraction: to separate clove oil from water

• Transfer distillate to a separatory (sep) funnel and add 10 mL of saturated NaCl solution to the sep funnel.

• Rinse condenser and receiving flask with 5 mL of ether and transfer this to the sep funnel.

• Swirl gently and vent the sep funnel.

• THEN, vigorously shake with

frequent venting.

ether layer

aqueous layer

Let the layers separate. Drain the aqueous layer (bottom layer). Transfer the ether layer (top layer) to a 50 mL E. flask.

Return the aqueous layer to the sep funnel. Extract two more times with 5 mLportions of ether (each time rinse the receiving flask and the condenser before adding to the sep funnel).

Dry the combined ether extracts over anhydrous Na2SO4 for 5 min. Decant as much as possible before removing the rest with a pipet.

Filter the ether solution through a cotton plugged pipet into a preweighed50-mL round bottom flask

Rinse the Na2SO4 with three additional 2-mL portions of ether and filter into the preweighed 50-mL round bottom flask.

Rotary Evaporation: Remove ether from your oil by rotary evaporation. Remove the last traces of ether with the house vacuum. Let it dry for one week.

- Determine % recovery of eugenol.

DO NOT dissolve eugenol in methanol!!!!

- Next week - converting eugenol to the ester derivative (get handout in your lab)

Omit : 1. TLC 2. The qualitative tests described in the module.

WasteWaste: - One bottle is in the hood for ether / water waste.

- DO NOT collect cloves! Decant water from the reaction flask into the sink, put cloves in a paper towl and throw in the trash.

Don't forget: You will also weigh, perform TLC, and measure the melting point for each of your compounds from last week. You need to submit your samples in marked vials as instructed by your TA. You must turn in your TLC plates with your lab report in an envelope or zip lock bag.

Final Notes