Preparation of clove oil Extract by steam distillation from whole cloves

Backround information Cloves are the dried buds of a tree that is cultivated primarily in Zanzibar and Madagascar. The tree produces abundant clusters of small red flower buds that are gathered before opening and are dried to produce the dark-brown, nail-shaped spice clove. Whole and ground cloves are popular food seasonings and account for the use of half the world production of cloves. The other half is ground and used in the manufacture of a type of cigarette popular in Indonesia. Almost 20 percent of the clove's weight is essential oil, obtained by distillation and used in perfumes, blends of spices, medicines, and sweets. Clove oil is a powerful antiseptic, and is also used as a local anaesthetic for toothache.

Why steam distillation When two or more immiscible liquids are heated, the total vapour pressure over these liquids is equal to the sum of the individual vapour pressures. This allows substances to be distilled that, if heated on their own to higher temperatures, might suffer partial decomposition or charring. In this experiment the initial products of the steam distillation will be clove oil and water Clove oil contains component molecules whose boiling points are quite high. Heating to their boiling point would destroy the molecular content.

Practical precautions The bottom of the safety tube should be well below the water surface in the steam generator, but not touching the bottom of the flask. The use of Bibby clips is handy to hold the parts of the assembled Quickfit apparatus together. It is inadvisable to use powdered cloves. If they are used, the steam inlet may become blocked. Place an adequate supply of water in the steam generator. Make sure the level of the boiling water in the steam generator does not fall too low. After 20 to 30 minutes disconnect the steam generator to avoid the possibility of suck-back problems and turn off the heat under it. Use anti bumping granules in steam generator. Steam can cause serious burns. Make sure that each experimental set-up is firmly clamped with the two safety openings in place. The first safety valve is in the Quickfit steam generator. The second safety valve is part of the delivery tube attached to the end of the Liebig condenser.