Investigating a Chemoselective Grignard Reaction in an Undergraduate Discovery Lab To Predict Reactivity and Final Products

A discovery-based Grignard experiment that emphasizes several important concepts in organic chemistry is reported. The Grignard reagent from 1-bromo-4-chlorobenzene was prepared and reacted with dimethylformamide (DMF) to synthesize 4-chlorobenzaldehyde. Students were tasked with predicting halogen...

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Bibliographic Details
Published in:Journal of chemical education 2016-08, Vol.93 (8), p.1464-1469
Main Authors: Maher, Michael J, Hayes, Colin O, Vaccaro, Francesca A, Flynn, Cailyn B, Thedford, R. Paxton, Stephenson, Clifton J
Format: Article
Language:English
Subjects:
Amides
Chlorobenzene
Chromatography
College Science
Curricula
Discovery Learning
Gas chromatography
Infrared analysis
Infrared spectroscopy
Louisiana (New Orleans)
Mass spectrometry
Melting
Melting point
Melting points
NMR spectroscopy
Organic Chemistry
Prediction
Reagents
Science education
Science Experiments
Science Instruction
Science Laboratories
Spectroscopy
Students
Thin layer chromatography
Undergraduate Students
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Summary:A discovery-based Grignard experiment that emphasizes several important concepts in organic chemistry is reported. The Grignard reagent from 1-bromo-4-chlorobenzene was prepared and reacted with dimethylformamide (DMF) to synthesize 4-chlorobenzaldehyde. Students were tasked with predicting halogen reactivity in the formation of the Grignard reagent, predicting the final product, and drawing a reasonable mechanism for the reaction with DMF. The Grignard reaction with tertiary amides is typically not discussed in the organic chemistry curriculum, so the students have an opportunity to apply concepts covered in lecture to a new situation. Lastly, the students experimentally verified the identity of the product using thin layer chromatography, melting point analysis, gas chromatography, IR and NMR spectroscopy, and mass spectrometry.
ISSN:0021-9584
1938-1328
DOI:10.1021/acs.jchemed.5b00453