Diethylzinc

Diethylzinc is an organozinc compound with the formula Zn(C2H5)2. It is a colorless to faintly yellow, very volatile liquid at room temperature. It is extremely air- and moisture-sensitive and is pyrophoric, igniting upon contact with air. In practice it is handled under inert atmosphere and typically used as a solution in hydrocarbon solvents such as hexane or toluene.

Preparation and handling: Diethylzinc is generally prepared by direct reaction of zinc metal with ethyl halides (for example, ethyl iodide or ethyl bromide) in dry ether solvents, producing Et2Zn and zinc halide. It can also be formed by transmetalation from other organozinc species. Because of its volatility and pyrophoricity, it is stocked in sealed, inert containers and transferred by syringe or cannula under an inert gas.

Reactivity and applications: As a source of ethyl groups, Zn(C2H5)2 participates in carbon-carbon bond-forming reactions, including additions to carbonyl compounds under appropriate conditions and various catalytic or stoichiometric transformations that generate organozinc intermediates. It is used in certain Negishi-type cross-couplings and related transformations where ethyl groups are transferred from zinc to electrophiles, and it can serve as a mild reducing/alkylating agent in specialized protocols. In all cases, handling is done under inert atmosphere due to its air sensitivity.

Safety: Diethylzinc is highly flammable and poses fire and explosion risks on contact with air or water. Vapors can form ignitable mixtures. It can cause serious eye and skin irritation and is toxic if inhaled. Storage and use require ventilation, inert atmosphere, and appropriate protective equipment.

See also: organozinc compounds, zinc, cross-coupling reactions.