Tetrabutylammonium hydroxide is widely used as a phase-transfer catalyst in organic synthesis, facilitating reactions between compounds in different phases, such as aqueous and organic layers. It is particularly effective in nucleophilic substitution reactions, where it enhances the transfer of anions to organic substrates. In analytical chemistry, it serves as an ion-pairing agent in chromatography, improving the separation and detection of various compounds. Additionally, it is employed in the preparation of quaternary ammonium salts and as a strong base in various chemical reactions. Its ability to stabilize anions and promote solubility in organic solvents makes it valuable in both industrial and laboratory settings.