Chemically biodiesel is the methyl ester of long of long chain carboxylic acids. It is also called as Green Fuel.

Biodiesel is obtained by trans esterification (means the process of converting one ester to another ester) of vegetable oil or animal fats with methyl alcohol using catalyst sodium metal or sodium methaxide.

A molecule of oil or fat is the triester of glycerol & 3 molecules of long chain carboxylic acids. This is converted into methyl esters of the fatty acids.

Moisture free oil or fat with less than 5% free acid & dry methanol or ethanol are taken in 1:3:5 molar ratio in a 3neck round button flask (with arrangement of magnetic stirrer & heating) & catalyst methoxiode maintained @2% by weight. The mixture is heated at $60^0 c$ 7 purified by using vacuum distillation.

Advantages of Biodiesel:

1. Cheaper
2. High cetane numbers 45 to 54 & high CV of @ 40KJ/gm.
3. Regenerative & environmental friendly. It causes less pollution.
4. It has certain extent of lubricity.
5. Clean to use in diesel engine.