Catalysis
Catalysis: Midterm Review
LECTURE 1:
Sept 6th 2012
What is catalysis, Importance of catalysis, Industrial relevance, presentation of the course
What is Catalysis:
Catalyst:
* catalyst is substance that increases the rate at which a chemical reaction approaches equilibrium, but is not consumed in the process * not reagent or product; noted above equation arrow * participates in kinetic equations, but not in eq constant
Catalytic Cycle: * succession of chemical changes undergone by the catalyst until it recovers its initial state
Catalysis=Kinetic phenomenon * catalyst creates alternative path for reaction, more complex but energetically much more favorable * smaller activation energy for catalytic reaction larger reaction rate * Catalyst changes the kinetics but not the thermodynamics * accelerates both forward and reverse reaction to the same extent
Some catalysts: * enzyme (biocatalyst) * copper zine crystallites on silica * homogenous acid catalysts * L-proline (organocatalyst) * Zeolite (crystalline aluminosilicate) * (R,R,)-DiPAMP-Rh (organometallic complex)
Homo/hetero-genous/bio-catalysis:
HOMOGENOUS: * catalyst and reagents are in the same phase * in solution – soluble and/or liquid reagents react in the liquid phase * Can be: organic molecules, transition metal complexes, inorganic salts, lanthanide complexes * Powers: * Efficiency of an homogeneous process * Fine tuning of activity with the choice of ligands * Greater selectivity (region, chemo selectivity) * Better potential for asymmetric catalysis * Better understanding of the catalyst structure * Limitation: * Problematic separation * Catalyst Cost – metal and ligands expensive * Homogenous catalysis used for complex reations in fine and pharmaceutical industry
HETEROGENOUS: * catalyst and reagents are in a different phase * maximize the surface *
LECTURE 1:
Sept 6th 2012
What is catalysis, Importance of catalysis, Industrial relevance, presentation of the course
What is Catalysis:
Catalyst:
* catalyst is substance that increases the rate at which a chemical reaction approaches equilibrium, but is not consumed in the process * not reagent or product; noted above equation arrow * participates in kinetic equations, but not in eq constant
Catalytic Cycle: * succession of chemical changes undergone by the catalyst until it recovers its initial state
Catalysis=Kinetic phenomenon * catalyst creates alternative path for reaction, more complex but energetically much more favorable * smaller activation energy for catalytic reaction larger reaction rate * Catalyst changes the kinetics but not the thermodynamics * accelerates both forward and reverse reaction to the same extent
Some catalysts: * enzyme (biocatalyst) * copper zine crystallites on silica * homogenous acid catalysts * L-proline (organocatalyst) * Zeolite (crystalline aluminosilicate) * (R,R,)-DiPAMP-Rh (organometallic complex)
Homo/hetero-genous/bio-catalysis:
HOMOGENOUS: * catalyst and reagents are in the same phase * in solution – soluble and/or liquid reagents react in the liquid phase * Can be: organic molecules, transition metal complexes, inorganic salts, lanthanide complexes * Powers: * Efficiency of an homogeneous process * Fine tuning of activity with the choice of ligands * Greater selectivity (region, chemo selectivity) * Better potential for asymmetric catalysis * Better understanding of the catalyst structure * Limitation: * Problematic separation * Catalyst Cost – metal and ligands expensive * Homogenous catalysis used for complex reations in fine and pharmaceutical industry
HETEROGENOUS: * catalyst and reagents are in a different phase * maximize the surface *