Ethylmagnesium

Ethylmagnesium refers to organomagnesium compounds in which an ethyl group is bonded to magnesium, most commonly the Grignard reagents ethylmagnesium chloride (EtMgCl) and ethylmagnesium bromide (EtMgBr). These compounds are highly reactive due to the polar carbon–magnesium bond and are used as strong nucleophiles and bases in organic synthesis.

Preparation and structure

Ethylmagnesium reagents are prepared by activating ethyl halides (ethyl chloride or bromide) with magnesium metal in an anhydrous ether solvent such as diethyl ether or tetrahydrofuran (THF). The halide identity, solvent, and concentration influence reactivity and aggregation. In solution they exist as aggregates that are solvated by the ether, often switching between monomeric and dimeric forms depending on conditions.

Reactions and uses

Ethylmagnesium reagents act as nucleophiles to form new carbon–carbon bonds. They add to aldehydes and ketones to give, after acidic workup, primary or secondary alcohols, respectively. Reaction with formaldehyde yields 1-propanol after hydrolysis; reaction with acetaldehyde yields a higher-order alcohol. Reaction with carbon dioxide affords propionic acid after workup. Epoxides undergo ring opening to yield extended-chain alcohols. Grignard reagents also react with nitriles to form ketones upon workup. They are commonly used to form alcohols, tertiary alcohols, and various carboxylic acid derivatives via subsequent transformations.

Laboratory considerations and safety

Ethylmagnesium reagents react vigorously with water and oxygen, and are typically prepared and used under strictly anhydrous, inert atmosphere conditions in dry solvents. They are moisture- and air-sensitive and can be hazardous, requiring appropriate protective measures. Quenching with water or alcohols releases heat and hydrocarbon byproducts such as ethane.

See also: Grignard reagent.