SN1 and SN2 Reactions
Module Overview
This module explores nucleophilic substitution reactions and how solvent selection correlates to reaction mechanisms for SN1 and SN2 reactions (i.e., reaction product, selectivity, and stereochemistry). Solvents are discussed with respect to environmental, health, safety, and life-cycle considerations. This module can be used when nucleophilic substitution reactions are introduced and is designed to replace approximately one week of class material. This module expands the typical SN1/SN2 discussion of solvents to include a systems thinking approach and interdisciplinary applications. Solvent choice relates directly to UN SDG 12: Responsible Consumption and Production and Green Chemistry principles 5 (safer solvents and auxiliaries), 1 (waste prevention), and 7 (renewable feedstocks).
Module Goal
Students will be able to evaluate molecular properties; health, safety and environmental impacts; and lifecycle to select and justify solvent choice for nucleophilic substitution reactions.
Audience
Second-year organic chemistry undergraduates
Class Time Requirement
Approximately four 50-minute class periods
Module Authors
Teresa Fernando, Iowa State University; Sarah A. Cummings, University of Nevada, Reno
Module Summary
Assumed Prior Knowledge
To successfully begin this module, students should be able to demonstrate knowledge of nucleophilic substitution introductory terms and concepts such as:
- Nucleophiles and electrophiles
- Nucleophilicity trends
- Alkyl halides
- Identification
- Nomenclature
- Reaction Coordinate Diagrams
- Exothermic vs. endothermic
- First and second order reactions
- Transition state and effect on reaction kinetics
- Stereochemistry
- Chirality
- Cahn-Ingold-Prelog naming system
- Carbocation rearrangements
Learning Objectives
Students will be able to:
- Identify a chemical reaction as SN2 and predict products, using arrow-pushing mechanisms, and applying chemo- and stereoselectivity concepts.
- Use molecular properties such as dielectric constant, H-bonding ability, boiling point to select solvent for SN2 reaction.
- Use systems thinking to analyze sustainability issues in choice of solvent for an SN2 reaction.
- Identify a chemical reaction as SN1 and predict products, using arrow-pushing mechanisms, and applying chemo- and stereoselectivity concepts.
- Use molecular properties such as dielectric constant, H-bonding ability, boiling point to select solvent for SN1 reaction.
- Use systems thinking to analyze sustainability issues in choice of solvent for an SN1 reaction.
Unit Overview
Formative assessments are interspersed within the Unit 1, 2, and 3 PowerPoints. Most often these are in the form of a class response. A few are Think Pair Share activities and two are Jamboard in-class activities. These are designed to incorporate active learning on a frequent basis to encourage student engagement with each learning objective.
Unit 1: SN2 and Introduction to Sustainability and Systems Thinking
| Lecture with PowerPoint slides and formative assessments. (50 minutes |
Unit 2: SN2 Sustainability and Introduction to SN1
| Lecture with PowerPoint slides and formative assessments. (50 minutes |
Unit 2: SN1 Stereochemistry and Sustainability
| Lecture with PowerPoint slides and formative assessments. (50 minutes |
Download Module
SN1 and SN2 Reactions Includes:
- Module Overview Document
- Units 1-3
- Formative Assessments
- Summative Assessments
Copyright Statement
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- Attribution required
- Allows remix of content
- Commercial use not allowed
About the Green Chemistry Module Project
The ACS Green Chemistry Instiute has partnered with chemistry instructors from over 45 institutions to develop green chemistry education resources for undergraduate students studying general and organic chemistry.
