Complete Proton and Carbon Assignment of (+)-Catechin via One- and Two-Dimensional Nuclear Magnetic Resonance (NMR) Analysis: A Hands-on Learning Experiment for Upper-Division Undergraduate Chemistry Students

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 11 Issue 1 (2006) pp 15-22

Complete Proton and Carbon Assignment of (+)-Catechin via One- and Two-Dimensional Nuclear Magnetic Resonance (NMR) Analysis: A Hands-on Learning Experiment for Upper-Division Undergraduate Chemistry Students

Shen-Chieh Chou, Jessica E. Mercier, Kimberly A. Wilson, and John J. Beck*

Department of Chemistry, Sweet Briar College, Sweet Briar, VA 24595, jbeck@sbc.edu
Received July 29, 2005. Accepted October 5, 2005.

Published online: 25 Novenber 2005

Abstract. Students from an upper-division undergraduate organic class analyzed one- and two-dimensional 400-MHz NMR spectral data from (+)-catechin hydrate in acetone-d₆. Guided assignment of all proton and carbon signals was completed via 1-D proton and carbon, nuclear Overhauser effect (nOe), distorsionless enhancement by polarization transfer (DEPT) 135, ¹H–¹H correlation spectroscopy (COSY), ¹H–¹³C heteronuclear single quantum coherence (HSQC), and ¹H–¹³C heteronuclear multiple bond coherence (HMBC) NMR experiments. Coupling constants for the aliphatic region were compared to the theoretical values as determined by the Karplus equation and vicinal angles as ascertained by molecular modeling of (+)-catechin. Carbon-13 signals for the aromatic and aliphatic regions were compared to calculated values obtained from both spectroscopic analyses books and computer software.

Key Words: Laboratories and Demonstrations; analytical chemistry; organic chemistry; NMR; spectroscopy; molecular modeling; phenols

(*) Corresponding author. (E-mail: jbeck@sbc.edu)

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Supporting Materials:

The following supporting material for this article is available: all ¹H and ¹³C 1-D and 2-D NMR spectra used for this project; a table of contents for said spectra; molecular modeling pictures that depict the angles used for determination of J values in the aliphatic region; a student worksheet that includes brief descriptions of select NMR experiments and a large structure of (+)-catechin. All supplementary NMR spectra are scanned images of actual printed spectra. This material can be downloaded in a Zip file (9.03 MB)