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Grignard Synthesis of Triphenylmethanol Lab Report Essay

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The Grignard Synthesis of Triphenylmethanol
Organic Chemistry Lab II
March 19, 2012

Abstract The purpose of this experiment was to synthesize the Grignard reagent, phenyl magnesium bromide, and then use the manufactured Grignard reagent to synthesize the alcohol, triphenylmethanol, by reacting with benzophenone and protonation by H3O+. The triphenylmethanol was purified by recrystallization. The melting point, Infrared Spectroscopy, 13C NMR, and 1H NMR were used to characterize and confirm the recrystallized substance was triphenylmethanol.
Introduction
A Grignard reagent is a type of organometallic, which consists of a bond between a metal and a carbon. There are three types of carbon-metal bonds: ionic, polar covalent, and …show more content…

Grignard reagents also react with the least hindered carbon on an epoxide to break the ring in order to relieve ring strain.

A reaction of the Grignard reagent and carbon dioxide results in an acid, and reaction of a nitrile and a Grignard reagent produce a carbonyl via an imine intermediate. These are show below, respectively.

Grignard reagents are reactive enough to also attach esters; however, two equivalents of the Grignard reagent are usually added because less then two equivalents leave a large quantity of unreactive ester. This reaction forms a tertiary alcohol.

Grignard reagents cannot be synthesized from alcohols because instead of reacting with the halide to form the Grignard reagent, the alcohol is deprotenated. Grignard reagents also cannot be synthesized from molecules with a carbonyl group.
Solvent choice is important in Grignard reagent formation. The solvent must be non-reactive with a negatively charged carbon (ex. acetone or anything even slightly acidic), and the solvent cannot have a carbonyl group. The solvent must be a volatile solvent that provides a blanket of solvent over the reaction solution so that oxygen and moisture in the air are excluded from the reaction. Oxygen and moisture in the air are very slightly acidic and would disrupt the synthesis of a Grignard reagent. Anhydrous ether (R2O) is often used as a solvent in creating Grignard reagents because it keeps out water and oxygen, makes the

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