! www.clutchprep.com
!
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
CONCEPT: ALKENES and ALKYNES
□ Alkenes/Alkynes are named by adding the suffix modifier (-________/-________) to the end of the root.
● Alkenes/alkynes receive ___________________ in numbering alkanes
● Location is assigned to the first double bonded carbon
EXAMPLE: Name the following compound:
a.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 2
CONCEPT: STABILITY OF ALKENES
□ Alkenes are also stabilized through _________________________________
● Since this is only possible with -R groups, the more substituted the alkene, the more ________________
EXAMPLE: Rank the following alkenes in order of lowest to highest heat of combustion.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 3
CONCEPT: CARBOCATION INTERMEDIATES — STABILITY
□ Carbocations are stabilized by a phenomenon called _________________________________
● Hyperconjugation is the delocalization of charge by the interaction of an empty p-orbital with an adjacent, eclipsed σ-bond
● Since this is only possible with -R groups, the more substituted the carbocation, the more ________________
EXAMPLE: Which of the following alkyl halides would generate the most stable carbocation?
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 4
CONCEPT: CARBOCATION INTERMEDIATES — REARRANGEMENTS
□ Carbocations will rearrange to an adjacent, more stable position if possible. This is called a ___________
● 1,2-Hydride Shift occurs when there is a ____________ located on an adjacent, more stable carbon.
● 1,2-Alkyl Shift occurs when only small __________ groups are located on an adjacent, more stable carbon.
● Ring Expansion occurs when a carbocation is adjacent to a 3, 4 or 5- membered ring.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 5
PRACTICE: Which of the following carbocations would be likely to rearrange? Draw each rearranged structure below.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 6
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 - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 7
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 - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 8
CONCEPT: HYDROHALOGENATION
General Reaction:
EXAMPLE: Provide the mechanism for the following addition reaction.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 9
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 - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 10
PRACTICE: Provide the mechanism and predict the product of the following reaction.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 11
CONCEPT: OXYMERCURATION-REDUCTION
General Reaction:
Mechanism:
1. Electrophilic Addition
2. Nucleophilic Substitution (SN2)
3. Reduction (demurcuration)
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 12
PRACTICE: Provide the mechanism and predict the product of the following reactions.
a.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 13
CONCEPT: HYDROBORATION-OXIDATION
General Reaction:
Mechanism:
1. Electrophilic Addition
2. Oxidation
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 14
PRACTICE: Provide the mechanism and predict the product of the following reactions.
a.
b.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 15
CONCEPT: CATALYTIC HYDROGENATION AND WILKINSON’S CATALYST
General Reaction:
PRACTICE: Provide the products for the following reaction.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 16
CONCEPT: INTRO TO REDOX
● Oxidation reactions involve an increase in the ______________ content of a molecule
● Reduction reactions involve an increase in the ______________ content of a molecule
EXAMPLE: Label the following transformations as oxidation or reduction.
a.
b.
c.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 17
CONCEPT: HALOGENATION
General Reaction:
Mechanism:
1. Electrophilic Addition
2. Nucleophilic Substitution (SN2)
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 18
CONCEPT: HALOHYDRIN FORMATION
General Reaction:
Mechanism:
1. Electrophilic Addition
2. Nucleophilic Substitution (SN2)
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 19
PRACTICE: Provide the mechanism and predict the product of the following reactions.
a.
b.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 20
CONCEPT: SYN VICINAL DIHYDROXYLATION
General Reaction:
EXAMPLE: Predict the product for the following multi-step reaction.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 21
CONCEPT: WEAK OXIDATIVE CLEAVAGE
Ozonolysis: Ketones + Aldehydes + Formaldehyde
PRACTICE: Predict the products of the following reaction
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 22
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 - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 23
PRACTICE: Predict the products and show the full mechanism for the following reaction
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 24
CONCEPT: OXIDATIVE CLEAVAGE
Strong Oxidative Cleavage: Ketones + Carboxylic Acid + Carbon Dioxide
PRACTICE: Predict the product of the following reaction.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 25
CONCEPT: OXIDATIVE CLEAVAGE
Cleavage of Alkynes: Carboxylic Acid + Carbon Dioxide
EXAMPLE: Predict the product of the following reaction.
ORGANIC - BROWN 7E
CH.5 + 6 - ALKENES AND REACTIONS OF ALKENES
Page 26
Top Related