cetiltrimetilammonio

Cetiltrimetilammonio refers to a family of quaternary ammonium salts in which a cetyl group (a 16-carbon saturated alkyl chain) is bound to a trimethylammonium head. The salts are typically formed with a counterion such as bromide or chloride; the common laboratory salt is cetyltrimethylammonium bromide (CTAB). The chemical formula for the bromide salt is C19H42BrN, reflecting the cetyl tail plus three methyl groups on nitrogen.

As a cationic surfactant, cetiltrimetilammonio compounds have a hydrophilic positively charged head and a hydrophobic hydrocarbon tail. They are water-soluble and tend to form micelles above a characteristic critical micelle concentration (CMC), which at 25°C for CTAB is typically around 0.9 mM. In solution, these surfactants can solubilize hydrophobic substances, stabilize colloids, and interact with negatively charged surfaces such as nucleic acids and many biomolecules.

Common uses include laboratory and industrial applications where a strong cationic surfactant is advantageous. CTAB is widely employed in molecular biology for plant DNA extraction because it helps separate DNA from polysaccharides and phenolic compounds. In materials science, CTAB serves as a structure-directing agent in the synthesis of mesoporous silica and other nanostructures, guiding the arrangement of pores and particles. It also functions as a surfactant and antimicrobial agent in certain formulations, though its use in consumer products is more restricted due to safety considerations.

Safety and handling: cetiltrimetilammonio salts are typically irritants and can be toxic to aquatic life. They should be handled with appropriate personal protective equipment, and released to the environment should be avoided or minimized. Waste should be disposed as hazardous chemical material according to local regulations.