Tetramethylammonium bromide is widely used in organic synthesis as a phase-transfer catalyst, facilitating reactions between compounds in different phases. It is also employed in the preparation of nanoparticles, where it acts as a stabilizing agent to control particle size and distribution. In biochemistry, it serves as a reagent for protein crystallization, aiding in the study of protein structures. Additionally, it is utilized in the electronics industry for the fabrication of semiconductors and as an electrolyte in electrochemical applications. Its role in analytical chemistry includes use as an ion-pairing agent in chromatography to improve separation efficiency.