Grignard Reaction Lab

Grignard is a reaction that is crucial to forming the new carbon-carbon bond. This is a two-part lab that teaches new techniques; the purpose of this lab is to introduce realistic organic synthesis and apply acid workup to produce triphenylmethanol. A Grignard reaction is characterized by the addition of a magnesium halide (an organomagnesium halide) to an aldehyde or a ketone in order to form a secondary or tertiary alcohol. These reactions are helpful because they serve as a crucial tool in performing important carbon-carbon bond-forming reactions (Arizona State University, 2018). This experiment aimed to observe the mechanisms of a Grignard reply to synthesize triphenylmethanol from benzophenone using phenylmagnesium bromide as the Grignard reagent.

In this experiment, the combined reactions are as follows. To start the experiment, the Grignard reagent, phenylmagnesium bromide, was formed by reacting bromobenzene with magnesium while using anhydrous diethyl ether as the solvent. Using anhydrous ether is crucial because if any water is present, the Grignard reagent will react with the water instead, which will ultimately terminate the reaction. Once formed, the Grignard reagent reacted with the benzophenone to form triphenyl magnesium bromide; this served as the Grignard adduct. From there, the Grignard adduct underwent an acid workup using aqueous 6M hydrochloric acid in order to form the product triphenylmethanol. Since water and magnesium bromide chloride was structured as side products after the adduct was hydrolyzed, the product was isolated using two separate extractions: an ether extraction and an aqueous extraction through a separatory funnel. The product was then purified using petroleum ether and recrystallized using boiling isopropyl