Let's look at some specific examples. Subtle changes in the sizes or positions of groups of atoms attached to the ring dramatically change the compound's flavor. Vanillin Vanillin has a soothing, pleasant aroma. Its molecular weight is relatively low, and it is fairly volatile. Cooking with vanilla vaporizes some of the vanillin molecules and fills the room with its aroma.
Molecules containing only carbon and hydrogen are mostly insoluble in water.
Vanilla present in the wood lignin of the wine barrels slowly leaches into the wine over time. Eugenol 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.