Use of 1H NMR in Assigning Carbohydrate Configuration in the Organic Laboratory

Abstract

This article describes a laboratory experiment suitable for an advanced undergraduate organic laboratory class that combines synthetic organic chemistry and 1H NMR in the determination of the identity of a simple carbohydrate. The focus of the laboratory course is the application of modern organic techniques and training in the use of high-resolution NMR in the undergraduate organic laboratory. The experiment described herein combines the cumulative knowledge of both lab technique and NMR sample preparation with data processing. Students are asked to acetylate an unknown methyl glycoside, to purify the product of the reaction by column chromatography, and to prepare and submit a sample for 1H NMR spectroscopy. Each student is required to process the raw FID data to determine the identity of their unknown sugar. The experiment demonstrates the use of the coupling constant in the determination of an unknown structure.