The Rearrangement of an Allylic Dithiocyanate: An Experiment for Organic or Physical Chemistry Using NMR Analysis

David W. Emerson , Spencer M. Steinberg and Richard L. Titus
Department of Chemistry, University of Nevada, Las Vegas, Las Vegas, NV 89154-4003
J. Chem. Educ., 2005, 82 (3), p 466
DOI: 10.1021/ed082p466
Publication Date (Web): March 1, 2005

Abstract

An experiment suitable for students who have taken either organic chemistry or organic and physical chemistry is described. The simple preparation and molecular rearrangement of thiocyanic acid, 2-methylene-1,3-propanediyl ester to 1-propene, (3-isothiocyanato-2-isothiocyanatomethyl) occurs readily in the temperature range of 65–90°C and progress of the reaction is readily tracked by proton NMR. The buildup and decline of the intermediate, thiocyanic acid, 2-(isothiocyanatomethyl)-2-propenyl ester, is readily seen. Start and stop methods for conducting the reaction in simple apparatus external to the NMR instrument are described thus making the experiment suitable for several students to do in a limited period of time without tying up the NMR for long periods. A controlled temperature probe for the NMR instrument is not needed. Advanced students can determine rate constants for the reactions, compute activation parameters, and observe solvent effects.

Keywords (Audience):

Upper-Division Undergraduate

Keywords (Domain):

Organic Chemistry

Keywords (Pedagogy):

Hands-On Learning / Manipulatives

Keywords (Subject):

Kinetics
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History

  • Received: August 03, 2009

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