A Safer, Discovery-Based Nucleophilic Substitution Experiment

Abstract

A discovery-based nucleophilic substitution experiment is described in which students compare the reactivity of chloride and iodide ions in an SN2 reaction. This experiment improves upon the well-known "Competing Nucleophiles" experiment in that it does not involve the generation of hydrogen halide gas. The experiment also introduces students to the subject of phase-transfer catalysis.

Practical Chemical Kinetics in Solution

“…Examples of kinetic studies of second-order reactions are abundant [35][36][37][38][39], for example, the bimolecular nucleophilic substitution (S N 2, or alternatively A N D N mechanism) reaction between pyridine and ethyl iodide (Scheme 3) [40]. Figure 3 shows the disappearance of the reagents and the formation of the pyridinium salt, as well as the result of attempting to fit the data using the first-order kinetic model (ln[py] vs time plot) or using the (adequate) second-order model (1/[py] vs time).…”

Unimolecular Nucleophilic Substitution (SN1): Structural Reactivity Evidenced by Colored Acid–Base Indicators

“…Nucleophilic substitution mechanisms represent a key topic in undergraduate organic chemistry, stemming from their use in the laboratory for preparative purposes and for the large number of these reactions occurring in living organisms . Both S N 1 (unimolecular) and S N 2 (bimolecular) reaction mechanisms are one of the first subjects studied in organic chemistry courses, as they are useful for understanding kinetic, energetic, and structural aspects of the organic compounds and the basic structure–reactivity relationship . Likewise, the three-dimensional structures of the substrate and the nucleophile, and the nature of the leaving group, are important features to understand the processes involved in nucleophilic substitution reactions …”

“…1 Both S N 1 (unimolecular) and S N 2 (bimolecular) reaction mechanisms are one of the first subjects studied in organic chemistry courses, as they are useful for understanding kinetic, energetic, and structural aspects of the organic compounds and the basic structure−reactivity relationship. 2 Likewise, the three-dimensional structures of the substrate and the nucleophile, and the nature of the leaving group, are important features to understand the processes involved in nucleophilic substitution reactions. 2 Because both reaction mechanisms play a central role in organic chemistry, a thorough understanding of them has long been sought.…”

“…2 Likewise, the three-dimensional structures of the substrate and the nucleophile, and the nature of the leaving group, are important features to understand the processes involved in nucleophilic substitution reactions. 2 Because both reaction mechanisms play a central role in organic chemistry, a thorough understanding of them has long been sought. 3 This understanding by students should be developed not only in lectures, but also during lab experiments to illustrate and corroborate the theoretical principles of the reactions.…”

Experimental Determination of Activation Energy of Nucleophilic Aromatic Substitution on Porphyrins

“…In this experiment, we determine the E a values of different NAS reactions using three different nucleophiles on a porphyrin dye. Other undergraduate NAS reactions are described that focus on the number, position, and nature of the electron-withdrawing groups, using varying experimental conditions and assays. − There are no experiments that both compare the E a of different nucleophiles, which gives insights into the mechanism, and use thin layer chromatography (TLC) as the analytical method. This lab experiment provides a basis to teach other concepts, such as nucleophile hardness and multistep reactions.…”