GRIGNARD REAGENT | REACTIONS | PREPARATION | …
In this experiment the Grignard reaction will be illustrated through thepreparation of benzoic acid formed in reaction of phenyl magnesium bromide with carbondioxide (eq. 2). Carbon dioxide, in the form of solid CO2, will be provided butthe phenyl magnesium bromide will be prepared from bromobenzene according to eq. 1, (R = C6H5),and then quenching with CO2 and isolation of the benzoic acid from theacidified reaction mixture (as shown in equations (2) and (3) below).
* The organomagnesium halides are known as Grignard reagents
An alternate approach would be to 1) brominate benzene to form bromobenzene, 2) form the Grignard reagent with magnesium and 3) react it with carbon dioxide to produce benzoic acid.
As soon as you are sure that the reaction is proceeding satisfactorily, add anadditional 6 mL of absolute ether through the top of the condenser. The reaction mixtureshould continue to boil but if it should become sluggish apply heat with aheating mantle until all but the tiniest flakes of the magnesium has disappeared(periodically stop the stirrer to check how much Mg remains; this may take up to 30 min.).If at any point during the process you appear to be losing ether from your reactionmixture, add a few more mL of ether through the top of the condenser via a droppingpipette, to keep the volume about 10-12 mL. You have now prepared a solution of phenylmagnesium bromide in ether and it should be used immediately in the next step.
The Synthesis Of Triphenylmethanol Via The ..
Bromobenzene is clear colorless to pale yellow liquid and is soluble in methanol, diethyl ether and slightly soluble in cold water. It is used to introduce a phenyl group via palladium-catalyzed coupling reactions like the Suzuki reaction. Bromobenzene can also be used to prepare a Grignard reagent, phenylmagnesium bromide. Bromobenze is a toxic substance, it has been shown to cause liver and nervous system damage if the compound is inhaled, ingested, or absorbed through the skin. Ungraded products supplied by Spectrum are indicative of a grade suitable for general industrial use. These materials may or may not have a Certificate of Analysis available.