Sensitive NMR method for detecting carbohydrate influx into competing chemocatalytic pathways

Area of Science:

• Chemical analysis
• Biomass conversion
• Spectroscopy

Background:

• Stable isotopes are crucial for tracking reaction pathways and determining product origins.
• NMR spectroscopy offers detailed insights into the precise location of stable isotope labeling.
• Current methods for analyzing isotope distribution in biomass products can be complex and time-consuming.

Purpose of the Study:

• To develop a simple and rapid assay for quantitative measurement of stable isotope distributions in biomass-derived products.
• To utilize routine instrumentation and commercially available carbohydrate substrates.
• To investigate the influence of potassium ions on Sn-Beta-catalyzed carbohydrate conversion reactions.

Main Methods:

• Quantitative reduction of biomass-derived products with sodium borohydride (NaBH4) to introduce hydrogen atoms at each carbon site.
• Utilizing 2D 1H-1H TOCSY NMR experiments to detect and differentiate between 13C and 12C labeled sites.
• Analyzing isotope patterns in chemically identical products to identify competing upstream reactions.

Main Results:

• The developed assay allows for rapid, quantitative measurements of isotope distributions.
• The method successfully detects the usage of competing upstream reactions based on observed isotope patterns.
• The study quantitatively assessed changes in Sn-Beta-catalyzed carbohydrate conversion reactions with and without potassium (K+).

Conclusions:

• The new assay provides a straightforward approach for analyzing stable isotope labeling in biomass-derived products.
• This method can reveal mechanistic details and provenance of products by identifying isotope distributions.
• Potassium ions were shown to alter initial reaction pathways in Sn-Beta-catalyzed carbohydrate conversion, specifically influencing the production of methyl lactate.