ArMgX

ArMgX refers to arylmagnesium halides, a class of Grignard reagents used in organic synthesis. The general formula is Ar-Mg-X, where Ar is an aryl group and X is a halogen (typically Cl, Br, or I). These reagents are highly reactive, moisture- and air-sensitive, and they form solvated complexes with ether solvents such as diethyl ether or THF.

Preparation and structure occur by transferring magnesium metal into an anhydrous solution of an aryl halide in dry ether under inert atmosphere. The resulting ArMgX species are usually prepared as solutions or suspensions and exist as dimeric or higher-order aggregates in solution, with complexation to the solvent stabilizing the reactive magnesium center.

Reactivity and key transformations include: reaction with carbon dioxide to yield the corresponding carboxylic acid after acidic workup; reaction with water or alcohols to form the corresponding hydrocarbon and Mg(OH)X salts; addition to formaldehyde or other carbonyl compounds to form primary or secondary alcohols after workup; and reaction with epoxides to give alcohols with chain extension. They are widely used to form new carbon–carbon bonds, enabling aryl-alcohols, diaryl carbinols, and extended carbon skeletons in a single sequence.

Representative examples include phenylmagnesium bromide (PhMgBr) and p-tolylmagnesium chloride (p-MeC6H4MgCl). Practical use requires strictly dry conditions, compatible solvents, and careful quenching. ArMgX reagents remain foundational tools in laboratory-scale synthesis and in the preparation of complex organic molecules.