E.g. Rinse the bromobenzene vial with ~ 0.5 ml of anhydrous ether.
1), which you will prepare from bromobenzene.
* The alkynyl Grignard reagents are prepared by deprotonating 1-alkynes with another Grignard reagent like Ethylmagnesium bromide. The Grignard Reaction. Add this rinse to the reaction vial via syringe. Bromobenzene is prepared by the action of bromine on benzene in the presence of Lewis acid catalysts such as ferric bromide. The chemical reaction between magnesium and bromobenzene is shows in below: The formation of Grignard reagent is solvated by diethyl ether which protects the reagent from attacked by water molecules. However, due to the high reactivity of these Grignard reagents, great care must be taken to keep the reactions as free from air and water as possible. The bromobenzene is reacted with magnesium metal to form phenylmagnesium bromide which is known as Grignard reagent. Preparation of Benzoic Acid using the Grignard Reaction In this experiment, the alkyl magnesium halide will be in the form of phenyl magnesium bromide (R = C6H5 in eq. Grignard 4 Once the reaction has started, introduce the rest of the bromobenzene solution in two portions via syringe. Wait 45 minutes. Reaction Scheme Biphenyl, which is formed from a coupling reaction between unreacted bromobenzene and Grignard reagent, is often observed as a major impurity in this reaction. Vinyl bromide and bromobenzene can be converted to corresponding Grignard reagents by reacting them with magnesium metal in anhydrous THF. 2004 Chem 2OB3 Lab Manual – Experiment 2. (If some of the ether is lost during reflux, replace it with additional anhydrous ether.)