Steam Distillation

• Steam distillation is used to isolate, separate or purify compounds that have low decomposition point.

• The compound to be distilled must be insoluble or only slightly soluble in water.

• The clove oil and the water will co-distill. Remember that both the water and the clove oil exert a vapor pressure. For this experiment water has the higher vapor pressure compared to the clove oil, consequently more water will distill.

• Most compounds, regardless of their boiling point, will distill at temperatures below that of boiling water.

Isolation of Clove Oil Using Steam distillation

Extraction of clove oil from water.

• The clove oil is separated from the water co-distillate by dichloromethane extraction.

• Any aqueous layer that might have been separated along with the extract will be removed with sodium sulfate anhydrous. This process of removing water or any aqueous layer is called "drying."

• The dichloromethane is removed by vacuum distillation using the rotary evaporator.

• The clove oil is weighed to determine percent yield.

Separation of eugenol from oil of clove

Oil of clove is the only official oil that owes its value to the Phenol eugenol.  Principle of the assay

Volatile oils that contain phenols when shaken with solutions of sodium or potassium hydroxide diminish in volume because of the ready solubility of the phenol constituents in alkali. The non-phenolic portion of the oil remains un dissolved. This property is used to isolate eugenol from oil of clove.

(1) Place 10 ml of the oil of clove in a well-cleaned flask,  (2) Add 100 ml of 5 per cent aqueous solution of potassium hydroxide and heat on boiling water bath with frequent shaking for 15 minutes Remove from the bath, cool to room temperature and permit to stand undisturbed for one hour.  (3) Separate the undissolved oil in a separating funnel.  (4) The aqueous layer is rendered acidic with 5% HCl, where an oily layer of pure eugenol separates.

Procedure

N.B.: The mixture is heated on water bath for 15 minutes to saponify any eugenyl acetate present in oil of cloves in addition to eugenol.

-Acetyl eugenol will be decomposed on healing with KOH forming potassium eugenolate and potassium acetate. Therefor, the assay will indicate the percentage of eugenol and acetyl eugenol. ·

-The potassium eugenolate dissolves in water leaving undissolved hydrocarbons, ketones, etc. which rise into the graduated neck of the flask and are measured. If stronger

solutions are employed the results obtained are 100 high, since the strong alkali exercises some solvent action on the non phenolic constituents, particularly on oxygenated compounds.

-Since the potassium salts of many phenols are more soluble than the corresponding sodium salts. the use of potassium hydroxide is preferred.

-For the determination of free eugenol, the same procedure is carried out, but without heating on the water bath. The amount of acetyl eugenol could be easily calculated.

People use the clove in many ways and forms to make medicine.

Clove (Syzygium aromaticum) is used for upset stomach. Clove oil is used for diarrhea, hernia, and bad breath. Clove and clove oil are used for intestinal gas, nausea, and vomiting.

Clove is applied directly to the gums (used topically) for toothache, for pain control during dental work, and for a complication of tooth extraction called “dry socket.” It is also applied to the skin as a counterirritant for pain and for mouth and throat inflammation. In foods and beverages, clove is used as a flavoring.

In manufacturing, clove is used in toothpaste, soaps, cosmetics, perfumes, and cigarettes. Clove cigarettes, generally contain 60% to 80% tobacco and 20% to 40% ground clove. Eugenol, one of the chemicals in clove, acts like menthol to reduce the harshness of tobacco smoke.

Type of solvent used with increase polarity

[Hexane, Diethyl ether, chloroform, Dichloromethane, ethyl acetate, Dimethyl

sulfoxide (DMSO), butanol, ethanol, methanol, water].