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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

This experiment features the following Vernier sensors and equipment.

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

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

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

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