Diethylaluminum cyanide (DEAC) is an organoaluminum compound with the formula (C₂H₅)₂AlCN. It is typically handled as a solution in toluene or hexane due to its pyrophoric nature and high reactivity with air and moisture. This compound is a colorless to pale yellow liquid under inert conditions. Its primary application is in organic synthesis as a versatile nucleophilic cyanating agent. Unlike traditional cyanide sources (e.g., NaCN, KCN), DEAC acts as a source of the cyanide anion in a controlled manner, allowing for the stereoselective addition of the CN group to carbonyl compounds. A classic and highly significant reaction is the addition to aldehydes to produce cyanohydrins, which are valuable intermediates for the synthesis of α-hydroxy acids, amino acids (via the Strecker synthesis), and other bioactive molecules. Its reactivity profile makes it particularly useful for the synthesis of complex, chiral molecules in pharmaceutical and fine chemical research. DEAC is a highly hazardous material. It is spontaneously flammable in air (pyrophoric) and reacts violently with water, releasing flammable gases. It requires strict handling under an inert atmosphere (argon or nitrogen) using specialized Schlenk line or glovebox techniques. Appropriate personal protective equipment and procedures for handling air-sensitive and pyrophoric reagents are mandatory.