What is the compound R–Mg–Br called?

The compound R–Mg–Br is known as a Grignard reagent. It is an organometallic compound that contains a bond between carbon and magnesium. In this formula, “R” represents an alkyl or aryl group, “Mg” stands for magnesium, and “Br” is a halogen, usually bromine. The general formula of a Grignard reagent is R–Mg–X, where X can be chlorine, bromine, or iodine.

Grignard reagents were discovered by the French chemist Victor Grignard in 1900, who later received the Nobel Prize in Chemistry in 1912 for this discovery. These reagents are prepared by reacting an alkyl or aryl halide with magnesium metal in dry ether. The ether solvent helps stabilize the reagent by coordinating with magnesium.

Grignard reagents are highly reactive because of the polar covalent bond between carbon and magnesium. The carbon atom in R–Mg–Br carries a partial negative charge, making it nucleophilic. This means it can attack electrophilic carbon atoms, especially those in carbonyl groups such as aldehydes, ketones, and esters. Through these reactions, Grignard reagents are used to synthesize alcohols, carboxylic acids, and hydrocarbons.

The term “metallic alkyl halide” can also describe these compounds because they contain both a metal and a halogen attached to an organic group. However, the most accurate and widely accepted name is Grignard reagent.

These reagents are sensitive to moisture and carbon dioxide. When exposed to water, they decompose to produce alkanes. Therefore, all Grignard reactions must be carried out in anhydrous conditions using dry glassware and solvents.

Grignard reagents are among the most important tools in organic synthesis and are fundamental in industrial and laboratory chemistry.