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ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
CONCEPT: GENERAL MECHANISM
□ Addition reactions are ones in which 1 ______ bond is broken and 2 new ______ bonds are formed.
● They are the inverse of ___________________ reactions
EXAMPLE: Provide the mechanism for the following addition reaction.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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CONCEPT: MARKOVNIKOV’S RULE
□ When we try to perform addition on asymmetric double bonds, we now get two possible products.
● Markovnikov’s Rule predicts that the carbocation will ALWAYS form on the _________ _______________ carbon
EXAMPLE: Provide the mechanism for the following addition reaction.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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CONCEPT: HYDROHALOGENATION
General Reaction:
EXAMPLE: Provide the mechanism for the following addition reaction.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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CONCEPT: RADICAL HYDROHALOGENATION
□ Recall the hydrohalogenation mechanism:
● ____________________ intermediate
● _____________________ addition of bromine
Compare to the radical mechanism that predominates in the presence of peroxide:
● ____________________ intermediate
● _____________________ addition of bromine
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 5
EXAMPLE: Provide the complete mechanism for the following radical hydrohalogenation.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 6
CONCEPT: ACID-CATALYZED HYDRATION
● Same reagents as acid-catalyzed dehydration, except starting with a _____________ __________ instead of an alcohol.
● Same as the general mechanism hydrohalogenation, except with _____________ as the nucleophile
● Remember that EVERY acid-cat. mechanism begins with ________________ and ends with ________________
General Reaction:
EXAMPLE: Provide the mechanism for the following addition reaction.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 7
PRACTICE: Provide the mechanism and predict the product of the following reaction.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 8
CONCEPT: OXYMERCURATION-REDUCTION
General Reaction:
Mechanism:
1. Electrophilic Addition
2. Nucleophilic Substitution (SN2)
3. Reduction (demurcuration)
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 9
PRACTICE: Provide the mechanism and predict the product of the following reactions.
a.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 10
CONCEPT: HYDROBORATION-OXIDATION
General Reaction:
Mechanism:
1. Electrophilic Addition
2. Oxidation
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 11
PRACTICE: Provide the mechanism and predict the product of the following reactions.
a.
b.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 12
CONCEPT: CATALYTIC HYDROGENATION AND WILKINSON’S CATALYST
General Reaction:
PRACTICE: Provide the products for the following reaction.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 13
CONCEPT: HALOGENATION
General Reaction:
Mechanism:
1. Electrophilic Addition
2. Nucleophilic Substitution (SN2)
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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CONCEPT: HALOHYDRIN FORMATION
General Reaction:
Mechanism:
1. Electrophilic Addition
2. Nucleophilic Substitution (SN2)
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 15
PRACTICE: Provide the mechanism and predict the product of the following reactions.
a.
b.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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CONCEPT: EPOXIDATION
□ Epoxides are added to double bonds using _________________ ____________
● Common reagents are _____________ and ___________
Mechanism:
□ Epoxides can also be generated though an intramolecular _______ reaction of halohydrins.
Mechanism:
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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CONCEPT: EPOXIDE RING OPENING
1. Acid-Catalyzed Ring Opening
Following protonation of the epoxide, the nucleophile will attack the side of the ring with the most ___________ character:
2. Base-Catalyzed Ring Opening
The strong nucleophile will attack the side of the ring that is ___________ substituted
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 18
CONCEPT: SYN VICINAL DIHYDROXYLATION
General Reaction:
EXAMPLE: Predict the product for the following multi-step reaction.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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CONCEPT: WEAK OXIDATIVE CLEAVAGE
Ozonolysis: Ketones + Aldehydes + Formaldehyde
PRACTICE: Predict the products of the following reaction
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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CONCEPT: OZONOLYSIS – FULL MECHANISM
The mechanism for ozonolysis proceeds through multiple intermediates.
●Ozonolysis is combined with either a reductive, or an oxidative workup
□ Reductive workup: S(CH3)2 or Zn/HOAc
□ Oxidative Workup: H2O2
Ozonolysis Mechanism:
Reductive Workup Mechanism:
Oxidative Workup Mechanism:
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
Page 21
PRACTICE: Predict the products and show the full mechanism for the following reaction
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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CONCEPT: OXIDATIVE CLEAVAGE
Strong Oxidative Cleavage: Ketones + Carboxylic Acid + Carbon Dioxide
PRACTICE: Predict the product of the following reaction.
ORGANIC - KLEIN 3E
CH.8 - ADDITION REACTIONS OF ALKENES
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