Tetrabutylammonium bromide (TBAB) is a white powder with a variety of uses, including:

Phase transfer catalyst: TBAB is a widely used catalyst for many processes, including alkylation, oxidation, reduction, and esterification. It's also used in the pharmaceutical, agrochemical, polymer, and powder coating industries.

Solvent: TBAB can act as a zwitterionic solvent in organic transformations.

Reagent: TBAB is used as a reagent for HPLC analysis.

Cosmetic ingredient: TBAB is used in cosmetics.