JoVE Science Education
Химия
органическая химия
Introduction to Catalysis

Introduction to Catalysis

JoVE Science Education
органическая химия
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JoVE Science Education органическая химия
Introduction to Catalysis
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2.13: Performing 1D Thin Layer Chromatography

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08:23 min
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March 04, 2015

Обзор

Source: Laboratory of Dr. Ryan Richards — Colorado School of Mines

Catalysis is among the most important fields of modern technology and presently accounts for approximately 35% of the gross domestic product (GDP) and sustenance of approximately 33% of the global population through fertilizers produced via the Haber process.1 Catalysts are systems that facilitate chemical reactions by lowering the activation energy and influencing the selectivity. Catalysis will be a central technology in addressing the energy and environmental challenges of modern times.

Принципы

Процедура

1. Preparation of 4-Nitrophenol Solution Mixed with Sodium Borohydride Weigh 14 mg of 4-nitrophenol and dissolve in 10 mL of DI water in a glass vial. Weigh 57 mg of sodium borohydride and dissolve in 15 mL of DI water. Mix the two solutions and magnetic stir for 30 min at room temperature to a uniform solution. Lab coat, safety goggle and gloves are needed as standard protocol protection. 2. Preparation of Catalyst Solution Weigh 10 mg of palladium on active carbon and palladium on granular carbon respectively. Weigh 10 mg of active carbon as control group. Transfer weighed catalysts to a vial and add 100 mL of DI water to each vial. Sonicate the vials with an output power of 135 W for 10 min until catalysts are well distributed in water. 3. Catalytic Reduction of 4-Nitrophenol Measure 1.15 mL of prepared 4-nitrophenol and sodium borohydride solution, transfer to a 5-mL glass vial. Record the color of solution in the vial, wait 10 min and record if there is any change in the color of solution. Add 1 mL of prepared palladium on active carbon catalyst solution to the vial, shake the vial by hand for 20 s. Observe reaction for 20 min, record when solution color starts to change and when solution color completely fades to transparent. Repeat same procedure with the palladium on granular carbon catalyst solution. Repeat same procedure with the active carbon catalyst solution. Compare the color change between three catalysts after 0, 5, 10, 15, and 20 min of reaction time. To quantify this change, measure UV-Vis spectra of the sample during the 20 min reaction interval.

Результаты

The reduction of 4-nitrophenol with a catalyst is a benchmark reaction in the literature for evaluating catalyst performance and measuring kinetics. Prior to the addition of catalyst, the color of the solution is light yellow, which corresponds to the 4-nitrophenol ion in alkaline conditions. Without the addition of a catalyst, the yellow color does not fade away, this indicates that the mixture system of 4-nitrophenol and sodium borohydride is stable. After the addition of palladium on active…

Applications and Summary

As a benchmark reaction, the catalytic application of nanoscale palladium particles can be extended to other fields. Similar to the reduction of 4-nitrophenol, which is a colorometric (the reaction is observed as a color change), the hydrogenation of chemical dyes can be accomplished with the same protocol. Chemical hydrogenation processes are very important in many industrial reactions as well as waste disposal. Researchers have found applications of catalysts in hydrogenation reactions in fields such as petrochemicals….

Ссылки

  1. Armor, J. What is catalysis? North American Catalysis Society. (2008).
  2. Thomas, J.M., Thomas, W.J. Principles and Practice of Heterogeneous Catalysis. Wiley-VCH. Germany (2015).
  3. Heck, R.F., Nolley, J.P. Palladium-catalyzed v Vinylic Hydrogen Substitution Reactions with Aryl, Benzyl and Styryl Halides. J. Org. Chem. 37 (14), (1972).
  4. Oberholzer, M., Frech, C. M. Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions. J. Vis. Exp. (85), e51444, (2014).
  5. Liu, J., Gao, A. X., Johnson, J. A. Particles without a Box: Brush-first Synthesis of Photodegradable PEG Star Polymers under Ambient Conditions. J. Vis. Exp. (80), e50874, (2013).
  6. Fowler, M. L., Ingram-Smith, C. J., Smith, K. S. Direct Detection of the Acetate-forming Activity of the Enzyme Acetate Kinase. J. Vis. Exp. (58), e3474, (2011).

ТРАНСКРИПТ

1. Preparation of 4-Nitrophenol Solution Mixed with Sodium Borohydride Weigh 14 mg of 4-nitrophenol and dissolve in 10 mL of DI water in a glass vial. Weigh 57 mg of sodium borohydride and dissolve in 15 mL of DI water. Mix the two solutions and magnetic stir for 30 min at room temperature to a uniform solution. Lab coat, safety goggle and gloves are needed as standard protocol protection. 2. Preparation of Catalyst Solution Weigh 10 mg of palladium on active carbon and palladium on granular carbon respectively. Weigh 10 mg of active carbon as control group. Transfer weighed catalysts to a vial and add 100 mL of DI water to each vial. Sonicate the vials with an output power of 135 W for 10 min until catalysts are well distributed in water. 3. Catalytic Reduction of 4-Nitrophenol Measure 1.15 mL of prepared 4-nitrophenol and sodium borohydride solution, transfer to a 5-mL glass vial. Record the color of solution in the vial, wait 10 min and record if there is any change in the color of solution. Add 1 mL of prepared palladium on active carbon catalyst solution to the vial, shake the vial by hand for 20 s. Observe reaction for 20 min, record when solution color starts to change and when solution color completely fades to transparent. Repeat same procedure with the palladium on granular carbon catalyst solution. Repeat same procedure with the active carbon catalyst solution. Compare the color change between three catalysts after 0, 5, 10, 15, and 20 min of reaction time. To quantify this change, measure UV-Vis spectra of the sample during the 20 min reaction interval.

Теги

CatalysisCatalystActivation EnergyArrhenius EquationEnzymesHomogeneous CatalystsHeterogeneous CatalystsNanoparticlesSupport MaterialActive SitesSurface AreaReaction MechanismAdsorption