Sodium tetraethylborate is primarily used as a reagent in organic synthesis, particularly in the formation of carbon-carbon bonds. It is often employed in coupling reactions, where it facilitates the transfer of ethyl groups to organic substrates, enabling the construction of complex molecular structures. This chemical is also utilized in the preparation of organoboron compounds, which are valuable intermediates in various chemical processes, including pharmaceuticals and agrochemicals. Additionally, it plays a role in the synthesis of polymers and materials science, where it aids in the modification of surfaces and the creation of specialized coatings. Its ability to act as a source of ethyl anions makes it a versatile tool in synthetic chemistry.