Eugenol

Eugenol (C10H12O2), is an allyl chain-substituted guaiacol, i.e. 2-methoxy-4-(2-propenyl)phenol. Eugenol is a member of the allylbenzene class of chemical compounds. It is a clear to pale yellow oily liquid extracted from certain essential oils especially from clove oil and cinnamon.

It's slightly soluble in water and soluble in organic solvents. It has a pleasant, spicy, clove-like odor. Eugenol is found in bay leaves, allspice, and oil of cloves.

Eugenol has a short hydrocarbon chain attached to the ring, which makes it much less water-soluble than vanillin. Although it is practically insoluble in water, it freely mixes with fats and oils.

Its fat solubility allows it to penetrate tissues and bind more tightly to the vanilloid receptor, which is believed to have a fatty side chain. The tail gives eugenol a stronger odor than vanillin has. One bay leaf is enough to season a pot of soup; more than one or two ground cloves overpower a pumpkin pie.

 Eugenol has a numbing, analgesic effect. It is used as a dental antiseptic (it's one component of that strange smell some dentist's offices have). Why is the molecule an antiseptic? Apparently the hydrocarbon tail in combination with the polar OH group on the ring make eugenol rather soap-like, and it can disrupt the cell membranes of bacteria the way soap disrupts a spot of grease.

Overdose is possible, causing a wide range of symptoms from blood in the patient's urine, to convulsions, diarrhea, nausea, unconsciousness, dizziness, or rapid heartbeat.
Eugenol