Overview

In groups, students analyze and sort 5 substituents based on whether they are activating or deactivating groups at a whiteboard or interactive board. Groups switch boards to peer review and annotate another group's work before returning to their original board to discuss the comments made by their peers.

Each group then selects one activating and one deactivating substituent from their sorted compounds to add to the benzene ring. They draw resonance structures for both. This is followed by another period of peer review and annotation by another group.

The instructor then assigns each group a distinct reagent to carry out electrophilic ...

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In groups, students analyze and sort 5 substituents based on whether they are activating or deactivating groups at a whiteboard or interactive board. Groups switch boards to peer review and annotate another group's work before returning to their original board to discuss the comments made by their peers.

Each group then selects one activating and one deactivating substituent from their sorted compounds to add to the benzene ring. They draw resonance structures for both. This is followed by another period of peer review and annotation by another group.

The instructor then assigns each group a distinct reagent to carry out electrophilic aromatic substitution onto benzene rings attached to each substituent students previously sorted. Groups complete these five reactions, then once again switch whiteboards to peer review and annotate another groups work.

Groups then circulate around the room (gallery walk) to examine and discuss all finalized reactions posted by their peers. Each group compiles a flow chart outlining the steps required to solve a electrophilic aromatic substitution problem. Individual students then, out of class, apply their flow chart in solving related questions, modifying it until it is robust and using it as a study aid for future examinations.

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Objectives

Students will learn to identify and sort activating and deactivating substituents in electrophilic aromatic substitution, draw resonance structures for benzene, and examine substituent effects in electrophilic aromatic substitution.

Context and requirements

Level Grade 12-U0
Discipline Chemistry
Course Organic Chemistry
Activity Content Electrophilic Aromatic Substitution
Technological Requirements Whiteboards (or interactive whiteboards)
Best Use Practice, Review

Author’s Notes

Benefits

Students can review the work done by their peers, revisiting the content. They assess their own understanding by providing explanations for their work.

Challenges

If students don’t do the prior reading, it is difficult for them to participate in the activity. Consequently, incorporating a mini lecture or summary at the start of the activity can place students on a more even playing field.

Some groups are much faster than others. Additional steps or problems can be provided for students who have additional time.

Tips

If time is too short for a gallery walk, the instructor may compile the reactions completed by all groups, check them for errors, then distribute them, allowing students to construct the flow chart outside of class time. Another option is to have each group (or the instructor) post the reactions into an online collaborative platform.

When drawing out resonance structure, it is essential students realize that there is a loss of aromaticity. They must also realize the effect the substituent will have on subsequent substitution.

Including “exceptions” in the problems helps generate more discussions within each group. Students need to gain a better understanding of why the “exception” is truly an exception, and prevents students from blindly applying the same recipe to all problems.

Activity Pedagogical Components

Problem Solving

Working in GROUPS at a whiteboard, students complete a problem related to electrophilic aromatic substitution. This is completed IN CLASS.

Peer Review

In GROUPS, students switch boards with another group, discussing the other group’s work and annotating it with corrections. Students then return to their own board to discuss the comments made by their peers. This is followed by several further steps of problem solving then peer review, using problems of increasing difficulty. This work is completed IN CLASS.

Gallery Walk

In their GROUPS, students perform a gallery walk, inspecting and discussing the work done by other groups. This is done IN CLASS.

Creating A Tool

In their GROUPS, students create a heuristic (flowchart) for solving problems relating to electrophilic aromatic substitution. An emphasis should be placed on making this a general tool useful in solving a wide array of problems. This is done IN CLASS.

Refining A Tool

INDIVIDUALLY, OUT OF CLASS, students test their flowchart by applying it to more problems. They further refine the flowchart to incorporate any missing information.

Download Flowchart