Related Experiment Video
Updated: Mar 11, 2026
09:33
Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
Published on: February 7, 2022
4.0K
Kinetics of Levoglucosenone Isomerization
Siddarth H Krishna1, Theodore W Walker1, James A Dumesic1
1Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin, 53706, United States.
Chemsuschem
|November 19, 2016
Summary
This study details the acid-catalyzed isomerization of levoglucosenone (LGO) to 5-hydroxymethylfurfural (HMF). Reaction conditions, including temperature and acid concentration, were optimized to maximize HMF yield.
Area of Science:
- Biomass Conversion
- Chemical Kinetics
- Organic Chemistry
Background:
- Levoglucosenone (LGO) is a biomass-derived platform chemical.
- 5-Hydroxymethylfurfural (HMF) is a key biofuel and biochemical intermediate.
- Acid-catalyzed isomerization is a crucial step in converting LGO to HMF.
Purpose of the Study:
- To investigate the acid-catalyzed isomerization of LGO to HMF.
- To develop a reaction kinetics model for this conversion.
- To identify optimal conditions for HMF production and minimize degradation.
Main Methods:
- Experimental study of LGO isomerization under varying temperatures (100-150°C) and sulfuric acid concentrations (50-100 mM).
- Kinetic modeling to describe experimental data and reaction pathways.
- Analysis of HMF and levulinic acid yields with varying solvent compositions (water/tetrahydrofuran).
Main Results:
- Higher temperatures and shorter reaction times favor HMF production.
- Water presence is crucial for LGO isomerization; yields decrease with tetrahydrofuran addition.
- HMF is formed directly from LGO, not its hydrated derivative.
- Thermal and catalytic degradation of HMF are significant carbon loss pathways.
Conclusions:
- The developed kinetic model accurately describes LGO isomerization to HMF.
- The reaction mechanism involves anhydro bridge hydration followed by ring rearrangement.
- Optimized conditions and understanding degradation pathways are key for efficient HMF production from LGO.
Related Concept Videos
02:05SN1 Reaction: Kinetics
9.8K
In an SN2 reaction, the reaction rate depends on both the type of nucleophile and the substrate. A hindered tertiary alkyl halide is practically inert to the SN2 mechanism despite using a strong nucleophile.
However, Sir Christopher Ingold and Edward D. Hughes, who studied the kinetics of various nucleophilic substitution reactions, noticed that a tertiary alkyl halide does undergo a nucleophilic substitution reaction in the presence of a weak nucleophile. While studying the substitution...
However, Sir Christopher Ingold and Edward D. Hughes, who studied the kinetics of various nucleophilic substitution reactions, noticed that a tertiary alkyl halide does undergo a nucleophilic substitution reaction in the presence of a weak nucleophile. While studying the substitution...
9.8K
02:46E1 Reaction: Kinetics and Mechanism
18.3K
Here, in contrast to the E2 reaction mechanism, we delve into the aspects of the E1 reaction mechanism, which has two steps: rate-limiting loss of the leaving group and abstraction of the beta hydrogen by a weak base. Typically, the experimental proof for the E1 mechanism is via kinetic studies or isotope studies. While the former demonstrates the first-order kinetics—the dependence of the reaction solely on substrate concentration—the latter proves the abstraction of hydrogen only...
18.3K
02:45E2 Reaction: Kinetics and Mechanism
13.0K
SN2 substitutions and E2 eliminations of alkyl halides proceed via a concerted pathway. While the nucleophile attacks the alpha carbon in SN2 reactions, it functions as a strong base and abstracts a beta hydrogen in the E2 mechanism. The rate-limiting transition state in E2 elimination reactions is characterized by partially broken carbon–hydrogen and carbon–halogen bonds and a partially formed pi bond between the alpha and beta carbons. The beta hydrogen and halide are eliminated...
13.0K
02:14SN2 Reaction: Kinetics
10.5K
Kinetic Studies and Significance
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a...
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a...
10.5K
01:19Enzyme Kinetics
105.4K
Enzymes speed up reactions by lowering the activation energy of the reactants. The speed at which the enzyme turns reactants into products is called the rate of reaction. Several factors impact the rate of reaction, including the number of available reactants. Enzyme kinetics is the study of how an enzyme changes the rate of a reaction.
Scientists typically study enzyme kinetics with a fixed amount of enzyme in the controlled environment of a test tube. When more reactant, or substrate, is...
Scientists typically study enzyme kinetics with a fixed amount of enzyme in the controlled environment of a test tube. When more reactant, or substrate, is...
105.4K
01:24Phase II Reactions: Glucuronidation
1.9K
Glucuronidation, a pivotal phase II biotransformation process, involves the coupling of glucuronic acid to a drug or xenobiotic. Given its widespread occurrence and critical role in drug metabolism, it's considered the most crucial phase II reaction. It enhances the water solubility of substances, aiding their expulsion from the body. The driving force behind these reactions is a group of enzymes known as UDP-glucuronosyltransferases (UGTs). UGTs facilitate the transfer of a glucuronic acid...
1.9K