Contact Information

Author
  • Colin L. Raston
  • Professor
  • School of Biomedical and Chemical Sciences
  • Univ. of Western Australia
  • 35 Stirling Highway
  • Crawley WA 6009
  • Australia
Email
Phone
6488 3045

Green Chemistry Laboratory: Benign Synthesis of 4,6-Diphenyl[2,2']bipyridine via Sequential Solventless Aldol and Michael Addition Reactions

Author Contact: clraston@chem.uwa.edu.au

Summary

This laboratory exercise teaches students some of the principles of green chemistry while simultaneously introducing them to several traditional organic reactions. All the reagents used in the experiment are relatively safe and the avoidance of volatile organic solvents reduces cost, waste and hazards. The ultimate pyridine product is reached in three steps. The first step is the solventless aldol condensation of benzaldeyde and acetophenone. In the second step, a solventless Michael addition of 2-acetylpyridine to 1,3-diphenylpropenone is performed. Then, lastly, a ring closure is performed by heating the diketone in a solution of ammonium acetate in acetic acid. While step three is not solventless it should be noted that acetic acid has the potential of being a renewable solvent formed from the oxidation of ethanol.

The synthesis can be completed in a three hour period with final student yields ranging from 60-90%. This experiment provides an instructor with the opportunity to introduce or further reinforce the topics of green chemistry, aldol condensations, Michael additions, the Krohnke pyridine synthesis, recrystallizations, thin-layer chromatography, IR spectroscopy, carbon NMR, and diastereotopic hydrogens and their evidence in proton NMR.

Supplemental information includes a background section, experimental procedures, post-lab questions, spectroscopic information, instructor notes and tips.

Summary prepared January 2009 by Douglas M. Young at the University of Oregon.

Source

Cave, G. W.; Raston, C. L. J. Chem. Educ., Print 2005, 82, pp 468-469.

J. Chem. Educ. (Abstract only)

Category Descriptors

Chemistry Concepts
  • Addition Rxn
  • Aldehydes/Ketones
  • Alkenes
  • Amines-Ammonium Compounds
  • Carbonyl Chemistry
  • Elimination Reactions
  • Heterocycles
Laboratory Techniques
  • Heating and Cooling Methods
  • IR Spectroscopy
  • Measuring Mass and Volume
  • NMR Spectroscopy
  • Recrystallization
  • Thin-layer Chromatography
  • Vacuum Filtration
Green Chemistry Principles
  • Design Less Hazardous Chemical Syntheses
  • Increase Energy Efficiency
  • Maximize Atom Economy
  • Minimize the Potential for Accidents
  • Prevent Waste
  • Use Renewable Feedstocks
  • Use Safer Solvents/Reaction Conditions
Chemistry Subdiscipline
  • Environmental Chemistry
  • Organic Chemistry
Target Audience
  • Colleges/Universities
Source
  • Journal Articles