Grignard Formation of Crystal Violet

Introduction

An organometallic compound is one that contains a carbon-metal bond. The key feature of many of these compounds is that the carbon on the carbon-metal bond carries a partial negative charge. The partial negative charge on carbon makes it basic and nucleophilic; this latter property can be exploited in organic synthesis to help construct carbon-carbon bonds. Organomagnesium compounds are referred to as Grignard reagents.

Crystal violet is a triarylmethane dye which is commonly used in general chemistry classrooms to study spectrophotometry and basic chemical kinetics. Here, you will synthesize crystal violet by preparing a Grignard reagent from the bromine-containing compound 4-bromo-N,N-dimethylaniline. Addition of this Grignard to diethyl carbonate followed by acid hydrolysis ultimately leads to the triarylmethane dye.

Objectives

In this experiment, you will

  • Prepare a Grignard reagent from 4-bromo-N,N-dimethylaniline, illustrating the synthetic process of carbon-carbon bond formation.
  • Synthesize crystal violet from this Grignard reagent.
  • Analyze the purity of the synthesized crystal violet spectrophotometrically.

Sensors and Equipment

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Additional Requirements

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Standards Correlations

No standards correlations for this experiment.

Experiment 22 from Organic Chemistry with Vernier Lab Book

<i>Organic Chemistry with Vernier</i> book cover

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