What is Green's reagent? Green reagent, also called Grignard reagent, is alkyl magnesium halide. Chemical formula: R-MgX, where R refers to alkyl and X refers to halogen. Discovery of Green's Reagent 190 1 years ago, French chemist V.Grignard made an in-depth study of organomagnesium compounds and pointed out that the reaction of organomagnesium compounds was carried out in two steps. The first step is to generate them. The second step is the reaction of organic magnesium compounds with other reagents, for which he won the Nobel Prize in chemistry of 19 12. This reaction is realized by nucleophilic addition reaction with carbonyl-containing substances (aldehydes, ketones and esters), and it is a good reactant for nucleophilic addition reaction. It plays a special role in the synthesis of alcohol compounds, so this reaction is also called Grignard reaction. The use of Grignard reagent is very important in carbon chain extension, organic synthesis and organometallic chemistry. Taking the Grignard reaction of acetaldehyde with magnesium methyl iodide as an example, the mechanism is as follows: CH3CHO+CH3MgI=(CH3)2CHOMgI (catalyzed by anhydrous ether) (CH3) 2chomgi+H2O = (CH3).