Related Experiment Video
Updated: May 2, 2026
09:09
Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes
Published on: December 15, 2015
8.9K
Layered materials with coexisting acidic and basic sites for catalytic one-pot reaction sequences.
Ken Motokura1, Mizuki Tada, Yasuhiro Iwasawa
1Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Journal of the American Chemical Society
|May 22, 2009
Summary
Acidic montmorillonite-immobilized primary amines are novel bifunctional catalysts. These materials enable efficient one-pot tandem reactions, demonstrating coexisting acid and base sites for enhanced chemical synthesis.
Area of Science:
- Materials Science
- Catalysis
- Organic Chemistry
Background:
- Developing efficient catalysts for multi-step reactions is crucial in synthetic chemistry.
- Acid-base bifunctional catalysts offer unique advantages for tandem reactions.
- Montmorillonite clays are versatile supports for catalyst immobilization.
Purpose of the Study:
- To synthesize and characterize novel acid-base bifunctional catalysts based on acidic montmorillonite-immobilized primary amines (H-mont-NH(2)).
- To investigate the catalytic activity of H-mont-NH(2) in one-pot tandem reactions.
- To explore the influence of preparation conditions and catalyst structure on catalytic performance.
Main Methods:
- Immobilization of primary amines onto acidic montmorillonite.
- Characterization of the synthesized catalysts to confirm the presence of coexisting acid and base sites.
- Evaluation of catalytic activity in tandem deacetalization-Knoevenagel condensation reactions.
Main Results:
- H-mont-NH(2) materials exhibit excellent acid-base bifunctional catalytic activity.
- These catalysts are the first reported materials with active coexisting acid and base sites for tandem reactions.
- Tandem deacetalization-Knoevenagel condensation achieved quantitative yield using H-mont-NH(2).
- Catalyst acidity is significantly influenced by the preparation solvent.
Conclusions:
- Acidic montmorillonite-immobilized primary amines are highly effective bifunctional catalysts for one-pot tandem reactions.
- The coexisting acid and base sites facilitate synergistic catalytic effects.
- Interlayer acid sites enhance base-catalyzed reactions, showcasing the potential of these materials in green chemistry.
Related Concept Videos
02:50Catalysis
22.9K
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
22.9K
02:24Acid-Catalyzed Ring-Opening of Epoxides
7.2K
Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...
7.2K
01:01Acid Halides to Carboxylic Acids: Hydrolysis
2.7K
Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields...
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields...
2.7K
01:13Esters to Carboxylic Acids: Acid-Catalyzed Hydrolysis
3.2K
Hydrolysis of esters under acidic conditions proceeds through a nucleophilic acyl substitution. In the presence of excess water, the reaction proceeds in a reversible manner, forming carboxylic acids and alcohols.
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...
3.2K
01:15Acid-Catalyzed Aldol Addition Reaction
2.3K
The aldol reaction of a ketone under acidic conditions successfully forms an unsaturated carbonyl as the final product instead of an aldol. The acid-catalyzed aldol reaction is depicted in Figure 1.
2.3K
01:22Heterogeneous Catalysis
141
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
141