Inquiry-Driven Investigation of the Copper-Catalyzed Azide-Alkyne Cycloaddition in the Undergraduate Organic Chemistry Laboratory

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 20 (2015) pp 214-219

Inquiry-Driven Investigation of the Copper-Catalyzed Azide-Alkyne Cycloaddition in the Undergraduate Organic Chemistry Laboratory

Rebekah M. Moorman^†, Moujtaba Y. Kasmani^†, Christopher J. Peeples^†, Justin M. Chalker*^,‡

^†Department of Chemistry and Biochemistry, The University of Tulsa, Tulsa, Oklahoma, 74104 United States of America; ^‡School of Chemical and Physical Sciences, Flinders University, Bedford Park, South Australia, 5042, Australia, justin.chalker@flinders.edu.au
Received March 17, 2015. Accepted August 5, 2015.

Published: 20 August 2015

Abstract. An inquiry-driven activity suitable for an undergraduate organic or inorganic chemistry laboratory is presented. The activity centers on the copper-catalyzed azide-alkyne cycloaddition, a reaction that is widely used in chemical synthesis, biochemistry, and material science, yet one that is noticeably absent in most teaching laboratories. In the activity, students are charged with formulating a question or hypothesis regarding the reaction between ethyl azidoacetate and phenylacetylene. Given a panel of reagents and copper sources, the students must design and carry out experiments and appropriate control reactions to address their lines of inquiry. The reaction itself benefits from operational simplicity: it can be carried out in a test tube or beaker that is open to air, water is a suitable solvent, and the triazole product crystallizes directly from the reaction mixture, enabling isolation by simple filtration. This reaction also provides a link to contemporary issues in sustainable chemical synthesis such as catalysis, atom-economy, “click chemistry” and safe solvents. In implementing this teaching laboratory, students discovered hitherto unknown features of the copper-catalyzed azide-alkyne cycloaddition such as the detrimental effect of halides on the copper catalyst and the poor activity of copper iodide as a catalyst for the featured transformation. Herein, the development and implementation of the teaching laboratory is described, the diverse and creative lines of student inquiry are reported, as well as the novel aspects of this reaction that were discovered. The benefits of inquiry-driven, unscripted teaching laboratories are also discussed.

Key Words: Laboratories and Demonstrations; organic chemistry; inorganic chemistry

(*) Corresponding author. (E-mail: justin.chalker@flinders.edu.au )

Article in PDF format (239 KB) HTML format

Supporting Materials:

Detailed chemical and equipment list, student handouts, author-generated analytical data for triazole product (melting point, TLC analysis, NMR spectra, IR spectra, and mass spectrometric data) (2.55 MB).