Clove Oil

What are immiscible liquids?

Liquids that do not mix

What is the principle of steam distillation?

The boiling point of two immiscible liquids together is below the boiling point of both liquids separately

Why is steam distillation used to extract clove oil from cloves rather than direct distillation?

Clove oil has a high boiling point, if it were directly distilled the oil would decompose at the high temperature needed to bring the oils to a boil

What is the main constituent present in clove oil? Draw it

Eugenol

What kind of compound is eugenol? Why?

Aromatic compound, contains a benzene ring in its structure

What is the molecular mass of eugenol?

164

Give 3 safety precautions in this experiment

Safety tube placed in steam generator to prevent build up of pressure.

Steam trap collects any steam to avoid it condensing into the flask containing the cloves.

Gloves are worn as eugenol can burn the skin

Comment on the position of the safety tube in the steam generator

must be below the level of the water to prevent steam escaping

What two substances were collected during steam distillation?

water and clove oil as an emulsion

What is an emulsion?

Dispersion of small droplets of one liquid in another liquid in which it is not soluble

Describe the appearance of the water-clove oil emulsion

milky coloured liquid

Why are whole cloves used rather than powdered cloves?

whole cloves contain more oil

How is the clove oil separated from the emulsion?

By adding cyclohexane and performing a liquid-liquid extraction/solvent extraction

Give the procedure involved in the steam distillation of clove oil

Find mass of cloves with electronic mass balance

Set up apparatus for steam distillation

Bunsen burner switched on and steam is passed through the flask for 40 minutes/ until 50cm3 clove oil collected

Give the procedure involved in the solvent extraction

1.Emulsion added to separating funnel and add a small amount of cyclohexane with a dropper.

2. Stopper and shake and allow to settle.

3. Observe two separate layers form : organic layer of cyclohexane and clove oil on top and aqueous layer of water on bottom.

4. Allow bottom aqueous layer to drain into a beaker, organic layer drain separately into a conical flask.

5. The aqueous layer will still contain droplets of oil so it is added back into separating funnel with more cyclohexane and procedure is repeated at least two more times

What is liquid-liquid extraction/solvent extraction?

Used for separating two immiscible liquids. A solvent is added in which one of the liquids will dissolve but the other liquid will not.

Why is cyclohexane added to the emulsion?

Clove oil is soluble in cyclohexane but water is not. This dissolves the clove oil from the emulsion but does not dissolve the water

What safety procedure is taken when using the separating funnel to shake the mixture?

The separating funnel is inverted when shaking, and the tap is gently opened to relieve the pressure of vaporised liquid in the separating funnel, avoid pointing the funnel at another student

Why is this washing and separating procedure carried out atleast 3 times?

To extract the maximum amount of clove oil possible from the emulsion

AS each new washing is carried out, the emulsion becomes less milky. Explain

Milky colour is caused by the droplets of clove oil in the water as an emulsion. As each washing extracts more clove oil from the emulsion it becomes less milky

Why is anhydrous magnesium sulfate (MgSO4) added to the cyclohexane-clove oil mixture?

it is a drying agent - it absorbs and clumps any water remaining in the mixture

How much anhydrous magnesium sulfate should be added to the conical flask?

Until it settles at the bottom of the flask and no longer forms clumps

Why was the mixture filtered?

To remove any hydrated magnesium sulfate and excess magnesium sulfate from the mixture

Why was fluted filter paper used?

The surface area of fluted filter paper is greater - the filtration process is quicker

Why is the cyclohexane-clove oil mixture placed in a water bath?

Cyclohexane is a volatile organic solvent with a boiling point of 81C so placing the mixture in a water bath at 81C in a fume cupboard will cause the cyclohexane to boil off leaving the clove oil completely isolated behind

Why isn't a hotplate used to evaporate off the cyclohexane?

The clove oil would boil off with it

Why isn't a bunsen burner used to evaporate off the cyclohexane?

Cyclohexane is flammable

Give two industrial uses of clove oil

flavouring for meats, sweets, sauces and pickles

perfumes and soaps