Diethylaluminum chloride is primarily used as a catalyst or co-catalyst in various polymerization processes, particularly in the production of polyolefins like polyethylene and polypropylene. It is also employed in the synthesis of specialty chemicals, including organoaluminum compounds, which are essential in organic synthesis and the manufacture of fine chemicals. Additionally, it plays a role in the alkylation of aromatic compounds and in the production of linear alpha olefins. Its reactivity makes it valuable in Ziegler-Natta catalysis, enabling the creation of high-performance plastics and elastomers. In the pharmaceutical industry, it is utilized in the preparation of certain active pharmaceutical ingredients (APIs) through specific alkylation reactions.