CH3C6H4MgBr

CH3C6H4MgBr, also known as p-tolylmagnesium bromide, is an organometallic compound. It is a Grignard reagent, a class of compounds with the general formula R-Mg-X, where R is an organic group, Mg is magnesium, and X is a halogen. In this specific case, the organic group is a p-tolyl group (CH3C6H4-), which is a toluene molecule with a substituent at the para position. The halogen is bromine (Br).

This compound is typically prepared by the reaction of 4-bromotoluene with magnesium metal in an ethereal solvent, such as diethyl ether or tetrahydrofuran. The magnesium metal reacts with the carbon-bromine bond, forming the carbon-magnesium bond characteristic of Grignard reagents. The ethereal solvent is crucial as it solvates the magnesium atom, stabilizing the reagent and preventing unwanted side reactions.

Like other Grignard reagents, p-tolylmagnesium bromide is a strong nucleophile and a strong base. It readily reacts with electrophilic species, making it a valuable reagent in organic synthesis. It is commonly used to form new carbon-carbon bonds by reacting with carbonyl compounds (aldehydes, ketones, esters), epoxides, and other electrophilic substrates. For example, it can react with aldehydes and ketones to form secondary and tertiary alcohols, respectively, after aqueous workup. The p-tolyl group can be introduced into various organic molecules through these reactions. Due to its reactivity with protic solvents and oxygen, it is typically handled under an inert atmosphere, such as nitrogen or argon, and stored in anhydrous conditions.