28 Sep 2015

Working with Catalytic Cycles

In-Class Activity

Submitted by Matt Whited, Carleton College
Categories
Description: 

Students work in groups to identify relevant steps and intermediates in 3 catalytic cycles, all the while considering bonding (and electron counting) factors.  Following assignment of these steps and intermediate species, the students consider several questions related to catalysis more broadly, particularly the role of each reagent, how to speed up or slow down specific steps, and the importance of regiospecificity in certain steps.

AttachmentSize
File Catalysis In-Class Activity.docx189.98 KB
Learning Goals: 
  • Students will be able to apply knowledge of fundamental organometallic reaction classes to put together a catalytic cycle
  • Students will be able to consider the interplay of different steps and chemical species during catalysis, including structural factors allowing certain steps to occur
  • Students will be able to explain the role of accessible species not directly on the catalytic cycle and how these relate to the desired catalysis
Implementation Notes: 

Students worked in groups of 3-4, allowing me to circulate and help groups as they came upon problems.  After allowing sufficient time for their work (maybe 15 minutes), I had groups present their answers for discussion by the class.

Time Required: 
30 minutes
Evaluation
Evaluation Methods: 

Informal evaluation during group work and during group presentations

Evaluation Results: 

I most recently used this LO in the early weeks of a dedicated "Organometallic Chemistry" course after a fairly brief introduction to reaction mechanisms, as a way of transitioning to catalysis.  The students performed well on activity, easily completing the "fill-in-the-blank" problems, though they struggled a little more on the free response questions.  In particular, some groups needed help in assigning the role of HI in the Monsanto process.

Overall, this activity did a much better job than lectures I have used in past years to introduce catalysis.  Students identified key points where catalysis can be interrupted and factors to consider when thinking about overall rates and side products.

Creative Commons License: 
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