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  Home > JCE Print > Journal of Chemical Education > Issues > 2007  > October  >
In the Laboratory
Discovering Electronic Effects of Substituents in Nitrations of Benzene Derivatives Using GC–MS Analysis
Malgorzata M. Clennan and Edward L. Clennan
Department of Chemistry, University of Wyoming, Laramie, WY 82071
Cover
October 2007
Vol. 84 No. 10
p. 1679

Abstract
The nitration of six benzene derivatives having a range of substituents that differ in electronic effects were followed by GC–MS analyses of the crude reaction mixtures and adapted for the second-year organic laboratory. Students pool their results and identify the products by analyzing the mass spectral data of the isomers and by comparing them to the GC–MS analysis of authentic samples. Students determine which substituents predominantly direct nitration to the ortho- or para- and to the meta positions. This simple discovery-oriented experiment illustrates and reinforces the lecture material and provides students with first-hand knowledge of how textbook conclusions are determined in a laboratory situation.

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Supplement
Instructions for the students, notes for the instructor, chromatograms of reactions mixtures, and mass spectra of the major isomers are available.
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Citation
Clennan, Malgorzata M.; Clennan, Edward L. J. Chem. Educ. 2007, 84, 1679.
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Keywords
Aromatic Compounds; Constitutional Isomers; Electrophilic Substitution; Gas Chromatography; Hands-On Learning / Manipulatives; Inquiry-Based / Discovery Learning; Laboratory Instruction; Mass Spectrometry; Organic Chemistry; Second-Year Undergraduate
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History
Created:
Last Updated:
8/20/2007
9/7/2007
 Caution! 
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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