(E)-1,1,1-Trichloro-4-ethoxy-but-3-en-2-one is a chemical compound that is used as a solvent and as a reagent in organic synthesis. It has been used to prepare pyrazole derivatives with regiospecific substitution at the alpha position. 1,1,1-Trichloro-4-ethoxy-but-3-en-2-one can also be used to produce enamines and vinyl ethers by reacting with pyrrole or carbonyl groups. This chemical is an excellent catalyst for reactions involving heterocycles such as sulfates and isomeric chlorides. 1,1,1-Trichloro4ethoxybut3en2one reacts with diethyl ether in the presence of a base to form ethyl chloride.