What Is Sorbitan?
Sorbitan is an organic compound with the molecular formula C6H12O5 and a molecular weight of 164.16, commonly known as 1,4-sorbitan. It exists as a solid at room temperature.
It is formed by the intramolecular dehydration of sorbitol, resulting in a mixture of 1,4-sorbitan (five-membered cyclic ether) and 1,5-sorbitan (six-membered cyclic ether). Sorbitan with less than 1.5% water content is a light yellow viscous product with a pH of 4-7.
Uses of Sorbitan
Sorbitan is primarily used as a raw material for sorbitan fatty acid esters. These esters are produced by dehydrating the terminal hydroxyl groups of 1,4-Sorbitan and 1,5-Sorbitan in the presence of fatty acids like lauric acid, oleic acid, stearic acid, and palmitic acid, forming a variety of sorbitan fatty acid esters.
These esters, being nonionic surfactants, have hydrophilic groups (sorbitan) and hydrophobic groups (fatty acid esters), making them useful in applications such as emulsifiers, cosmetics, spreading agents, and industrial surfactants. Sorbitan is also utilized as an insecticidal fungicide.
Polysorbate, derived from sorbitan fatty acid esters and polyoxyethylene ether, is a more hydrophilic nonionic surfactant used in food emulsifiers, mouthwashes, and skin care products.
Other Information on Sorbitan
1. Sorbitan Production Process
Sorbitan is produced by the intramolecular dehydration of sorbitol, using solid acid catalysts like zeolite. Precise control of the reaction conditions allows selective production of sorbitan without forming isosorbide.
Sorbitan surfactants are produced by direct esterification with fatty acids, using acid or alkali catalysts or lipase. Polysorbate is synthesized by adding ethylene oxide to sorbitan fatty acid esters, with the surfactant properties varying depending on the ethylene oxide quantity.
2. Handling and Storage of Sorbitan
For proper storage, sorbitan should be kept in a tightly closed container in a well-ventilated place, away from direct sunlight and high temperatures. In case of skin contact, thorough washing with water and soap is recommended.