What do Grignard reagents do?

Question

Zoe Alexander · Accepted Answer

Enable #C-C# bond formation in organic chemistry.

The list of #C-C# bond forming reactions is quite small. Treatment of a hydrocarbyl halidie, of various identity, with metallic magnesium can result in the formation of an organometallic reagent in which the ipso carbon has carbanionic character: #R-X +MgrarrR-MgX# #R-MgX-=R^(delta-)-""^(delta+)MgX# Granted, there are limitations on the initial halide, and the reaction needs to be carried out in dry ether or another non-protic solvent. The Grignard reagent reacts (often quantitatively) with aldehydes, carbonyls, and ketones to permit the formation of secondary and tertiary alcohols following work-up. #R-MgX + R'C(=O)R''rarrR'R''C(-OMgX)R# Grignard can be simply poured onto dry ice to produce a carboxylate salt, which when dissolved in water, yields a carboxylic acid: #R-MgX + CO_2rarrRC(=O)O^(-)""^(+)MgX# If ethylene oxide is applied to the Grignard, two additional carbons can be added to the carbon chain, and these reactions are typically very simple to carry out and will tolerate a wide range of (non-protic) functionalities.

Delilah Anderson · Answer

undefined Grignard reagents are organometallic compounds commonly used in organic synthesis to introduce carbon chains onto organic molecules through nucleophilic addition reactions. They react with various electrophiles such as carbonyl compounds, alkyl halides, and epoxides, forming new carbon-carbon bonds.