Chem 109 C
Midterm 1 stats
Fall 2015
Armen Zakarian
Office: Chemistry Bldn 2217
Average
75
St Dev
Max
Min
13
96
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http://web.chem.ucsb.edu/~zakariangroup/courses.html
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CATALYSIS
CATALYSIS
Energy Diagrams:
Catalyst - a substance that
1.  accelerates a reaction, and
2.  is not changed or consumed
•  implication: the reaction still takes place without the catalyst, but is very slow
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important fact: the reaction rate is the rate of the slowest step
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Problem 1
Which of the following parameters would be different for
catalyzed vs uncatalyzed reaction (review Section 5.11)
ΔH‡,
ΔG°,
ΔG‡,
Ea, ΔS‡,
ΔS°,
ΔH°,
Which of the following parameters would be different for
catalyzed vs uncatalyzed reaction (review Section 5.11)
Keq
ΔG°,
krate
CATALYSIS
• 
base catalysis
• 
nucleophilic catalysis
• 
metal-ion catalysis
Ea, ΔS‡,
ΔS°,
ΔH°,
Keq
krate
important fact: the reaction rate is the rate of the slowest step
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ACID CATALYSIS
Two types of acid catalysis:
1. specific: first protonation, then slow step
Types of catalysis we will be looking at:
acid catalysis
ΔH‡,
ΔG‡,
important fact: the reaction rate is the rate of the slowest step
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• 
Problem 1
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ACID CATALYSIS
Two types of acid catalysis:
2. general: protonation and slow step at the same time
BASE CATALYSIS
Again, two types of base catalysis:
1. specific: first deprotonation, then slow step
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BASE CATALYSIS
Again, two types of base catalysis:
2. general: deprotonation and slow step at the same time
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CATALYSIS
PROBLEM 3
Are the slow steps here general-acid catalyzed or specific-acid
catalyzed?
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CATALYSIS
PROBLEM 4
The following reaction occurs by a general-acid catalyzed
mechanism:
OH
NUCLEOPHILIC CATALYSIS
the catalyst is a nucleophile
O
HB+
Propose a mechanism for this reaction
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NUCLEOPHILIC CATALYSIS
the catalyst is a nucleophile
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NUCLEOPHILIC CATALYSIS
the catalyst is a nucleophile
PROBLEM X
Draw an approximate energy diagram for the above reaction
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