Voltammetric Reductions of Ring-Substituted Acetophenones. 2. A Senior-Level Experiment Requiring Classification of an Electrochemical Mechanism as Stepwise or Concerted

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 7 Issue 2 (2002) pp 74-80

Voltammetric Reductions of Ring-Substituted Acetophenones. 2. A Senior-Level Experiment Requiring Classification of an Electrochemical Mechanism as Stepwise or Concerted

Grant N. Holder*, Laurel L. McClure, and David G. Farrar

Department of Chemistry, Appalachian State University, Boone, NC 28608
Received January 7, 2002. Accepted February 27, 2002

Published online: 15 March 2002

Abstract. An experiment suitable for upper-level undergraduates in which they determine the characteristics of a chemically coupled electron transfer (EC) mechanism is described. Students examine the free-energy barrier between an unstable radical anion and the products of its decomposition for ring-substituted and alpha-substituted acetophenones, acetanilides, and alkyl halides. Digital simulation is used to estimate the value of the standard potential, E^o. Calculation of the electrochemical transfer coefficient, a, allows a determination of whether the electron transfer occurs in a single step (concerted) or follows the generation of the intermediate radical anion (stepwise).

Key Words: Laboratories and Demonstrations; instrumental analysis; electrochemistry; radical

(*) Corresponding author. (E-mail: holdergn@appstate.edu)

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Supporting Materials:

Sample student-derived data tables (302 KB PDF) 10.1007/s00897020544b