Hammett Correlations of Benzhydrylium Cations

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 17 (2012) pp 053-056
DOI 10.1007/s00897122413a

Hammett Correlations of Benzhydrylium Cations

William H. Parsons, Louisa Hong, J. Hodge Markgraf^‡, and Sarah L. Goh*^,†

Department of Chemistry, Williams College, Williamstown, MA 01267-2692 USA, sgoh@williams.edu
Received July 17, 2010. Accepted January 16, 2011.

Published: 23 March 2012

Abstract. This laboratory experiment investigates linear free energy relationships between Hammett s⁺ parameters and the ¹H-NMR chemical shifts of substituted benzhydrol reagents. The significance of resonance and field effects on proton shielding can be determined by relating chemical shift data to various forms of Hammett equations. Benzhydrylium cations can be studied as well by ¹³C-NMR spectroscopy.

Key Words: Laboratories and Demonstrations; physical organic chemistry; linear free energy relationships; Hammett correlations

(*) Corresponding author. (E-mail: sgoh@williams.edu)

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Supporting Materials:

A student handout and synthesis and characterization data of benzhydrols derivatives that are not commercially available are provided in the supporting materials. ¹H-NMR spectra and ¹³C-NMR data for 2 are also include (872 KB).