Eugenol

Eugenol is the main ingredient of essential oil that can be isolated from the ground clove. The clove is the bud of East Indian evergreen tree. Eugenol is used in perfumery, for manufacture of synthetic vanillin, as a dental analgesic, and as an antiseptic.

In this experiment, we will extract the essential oil of cloves, which I mostly eugenol. The procedure used is the typical for isolating products from natural sources. The oil of cloves is isolated by the distillation of cloves. The crude eugenol is purified by forming its water-soluble sodium salt.

Procedure:

Natural product extraction

Five gram of ground cloves was placed in a 250 mL round-bottom flask with 150 mL of water and 2 drops of antifoaming agent were added. The mixture was distilled [1]. 50mL of distillate, contains the oil from the cloves dispersed in water, was collected in a 100 mL beaker.

Note [1]: In this experiment, distillation was used instead of steam distillation.

Purification (acid/base extraction) and isolation of Eugenol

The collected distillate was placed in 250 mL separatory funnel and extracted with three 15-mL portions of dichloromethane. This was to be performed inside the fume hood and regularly vented by opening the stopcock. The dichloromethane extracts were combined in a 100 mL conical flask [the aqueous layer was discarded].

Anhydrous calcium chloride pellets were added to the solution until the drying agent no longer clump together to dry the solution in about 2 minutes of swirling. The solvent was decanted into a dry 250 mL separatory funnel then extracted with three 10-mL portions of 5% NaOH solution.

All aqueous extracts were collected in a 100 mL conical flask and acidified to pH 1 using concentrated HCl. Congo red was used to test the acidity. Note: the extract was said to be have been acidified when it turned very cloudy.

The extracts were transferred in a 250-mL separatory funnel and extracted with three 8-mL portions of dichloromethane. Anhydrous calcium...