Chemistry

Lipids


Lipids are of great importance to the functioning of the body of humans.

They constitute animal and vegetable oils and fats.

They can be found in foods such as butters and margarines, olive oil, oils, hams, salami and in high fat fruits such as avocado.

        

The word lipid comes from the Greek term. liposwhich means "fat". Lipids are water insoluble and soluble substances in organic solvents such as chloroform, benzene and ether.

Lipids can be classified into simple and complexes.

Simple lipids are fatty acid esters with different alcohols. Fatty acids are normal chain monocarboxylic acids which may be saturated or unsaturated.

Some saturated fatty acids

Lauric acid - C11H23 - COOH - Coconut Fat

Myristic acid - C13H27 - COOH - Nutmeg

Palmitic acid - C15H31 - COOH - palm fat

Stearic acid - C17H35 - COOH - ox fat

Some unsaturated fatty acids

Oleic acid - C17H33 - COOH - olive oil
Linoleic Acid - C17H31 - COOH - soybean oil

Linolenic Acid - C17H29 - COOH - Flaxseed Oil

Unsaturated fatty acids may be monounsaturated with only one double bond or may be polyunsaturated with more than one double bond.

Oleic acid is monounsaturated, with unsaturation between carbons 10 and 9.

Linoleic acid is polyunsaturated, with unsaturation between carbons 13 and 12 and between 10 and 9.

Linolenic acid has three unsaturation, therefore polyunsaturated, with unsaturation at carbons 16 and 15, 13 and 12 and between carbons 10 and 9.

The most common alcohol in simple lipids is glycerin.

Glycerin is a tri-alcohol that acts in the formation of vegetable and animal oils and fats (esters, glycerides). Waxes are esters of long chain alcohol fatty acids.

Complex lipids are generally not esters. They are large, cyclic molecules and may contain nitrogen, phosphorus, etc.