Grignard Reaction

GRIGNARD REACTION (Grignard) consists in the preparation of various organic substances by means of organomagnesium compounds. Grignard found that iodine and bromine derivatives of hydrocarbons in the presence of ether react with metallic magnesium, forming compounds of the composition R.Mg.Br (or I), e.g.:

C₂H₅I + Mg = C₂H₅MgI; magnesium-ethyl-iodide C₆H₅Br + Mg = C₆H₅MgBr; magnesium-phenyl-bromide. Organomagnesium compounds possess great reactivity. The fields of their application in organic synthesis are extremely numerous and diverse. They are decomposed by water with the formation of hydrocarbons; by means of organomagnesium compounds, secondary alcohols are prepared from aldehydes, tertiary from ketones, primary alcohols from formaldehyde; carboxylic acids can be obtained with CO₂, aldehydes are formed with esters of formic acid, and ketones with esters of other organic acids. These reactions by no means exhaust the diverse transformations carried out by means of organomagnesium compounds. The latter react with nitriles, acid halides and anhydrides, and many other compounds used for the preparation of various substances. The simple and convenient execution of the Grignard reaction, relatively large yields, and the purity of the resulting products have made it one of the most frequently used methods of organic synthesis.