The Chemistry of Perfume

When your mom is going to a party you'll have seen her

spray on some expensive perfume.

Why does she do this?

What's the secret in the bottle?

We encounter perfumes and fragrances in a large proportion of the products we come into contact with each and every day such as shampoos, personal fragrances and cleaning products. What is actually a P-E-R-F-U-M-E? Perfume is a substance that gives off a pleasant odor. The word perfume comes from the Latin word, perfumare which means "through smoke". There are thousands of chemicals that are used in perfumes. But many of them can be grouped according to their chemical properties. One such group is esters.

Do you know that esters that make up perfumes and sweet fruity flavorings start out with bad smelling organic acids, like butyric acid (which gives rancid butter its odor), acetic acid (sharp smell of vinegar) or caproic acid, which commonly known as haxanoic acid due to the smell of goats in a barnyard. These foul smelling acids combine with odorless alcohol such as methanol and ethanol to produce pleasant smelling floral scents used in perfumes, candies, candles and desserts. 

Esters are made by reacting an alcohol with an organic acid. A small amount of sulphuric acid is needed as catalyst. The general equation for the reaction is:

Alcohol + Organic acid   →  Ester + Water

The diagram shows the process and where the water comes from

Ester have small molecular weight and very nice odor. They are responsible for the pleasant odor in jasmine, roses, apples, durian and many more. The higher the molecular weight, the weaker the odors they carry. Do you know that unsaturated esters have stronger odor than the saturated ones? Beside used in fragrance and flavoring industries, esters are also used as fixatives and carrier solvents. 

Benzyl Acetate is one of the thousands of esters used in making perfumes. Benzyl Acetate is produced from the condensation reaction of benzyl alcohol and acetic acid. It provides a basic odor that can be found in many perfumes and other cosmetic products. The characteristics of Benzyl Acetate are combustible, clear colorless liquid, has pungent or bitter taste, very low solubility in water, stable under ordinary conditions and is found naturally in flowers. 

Formula of Benzyl Acetate is C₆H₅CH₂OCOCH₃

Different esters have different smell. 

Alcohol	Organic acid	Ester made	Smell of ester
Pentanol	Ethanoic acid	Pentyl ethanoate	Pears
Octanol	Ethanoic acid	Octyl ethanoate	Bananas
Pentanol	Butanoic acid	Penthyl butanoate	Strawberries
Methanol	Butanoic acid	Methyl butanoate	Pineapples

LET'S MAKE OUR OWN!

You'll need some pure alcohol, water and a few drops of  lemon and orange essence. Mix alcohol and water in the ration 70:30 and add five drops of lemon essence and 5 drops of orange essence. Pour the mixture into your favorite empty scent bottle. There you have it!! 

A light fragrance called eau-de-Cologne for yourself!!