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  Home > JCE Print > Journal of Chemical Education > Issues > 2007  > November  >
In the Laboratory
Synthesis of Triarylmethane and Xanthene Dyes Using Electrophilic Aromatic Substitution Reactions
James V. McCullagh and Kelly A. Daggett
Department of Chemistry and Biochemistry, Manhattan College, Riverdale, NY 10471-4098
Cover
November 2007
Vol. 84 No. 11
p. 1799

Abstract
The synthesis of dyes has long been a popular topic in organic chemistry laboratory experiments because it allows students to see first hand that reactions learned in class can be used to make compounds with useful applications. In this experiment electrophilic aromatic substitution reactions are used to synthesize several triarylmethane and xanthene dyes (fluorescein, erythrosin B, thymolphthalein, and rhodamine B). These dyes can be readily synthesized using equipment found in most common second-year organic labs. Hydroscopic Lewis acids, which are often troublesome to use in a typical lab setup, are avoided. The dyes synthesized in this experiment can each be completed in one four-hour laboratory session. Approximately 30 minutes in a subsequent period will be required for UV–vis analysis, and the student samples give UV–vis spectra that match commercially available dye samples.

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Supplement
Background material for the students and detailed instructions as well as instructor notes, pictures, and UV–vis spectral data are available.
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Citation
McCullagh, James V.; Daggett, Kelly A. J. Chem. Educ. 2007, 84, 1799.
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Keywords
Acids / Bases; Aromatic Compounds; Dyes / Pigments; Electrophilic Substitution; Equilibrium; Hands-On Learning / Manipulatives; Laboratory Instruction; Organic Chemistry; Second-Year Undergraduate; Synthesis; UV-Vis Spectroscopy
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History
Created:
Last Updated:
9/19/2007
9/27/2007
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Experiments, laboratory exercises, lecture demonstrations, and other descriptions of the use of chemicals, apparatus, instruments, computers, and computer interfaces are presented in the Journal of Chemical Education as illustrative of new or improved ideas or concepts in chemistry instruction and are directed at qualified teachers. Although every effort is made to assure and encourage safe practices and safe use of chemicals, the Journal of Chemical Education cannot assume responsibility for uses made of its published materials. Many chemicals are hazardous. Precautions for the safe use of hazardous chemicals and directions for their proper disposal are described in the Material Safety Data Sheets and on the labels. We strongly urge all those planning to use materials from our pages to make choices and to develop procedures for laboratory and classroom safety in accordance with local needs and situations.
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