ch.5 + 6 - alkenes and reactions of...

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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


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


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


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


PRACTICE: Which of the following carbocations would be likely to rearrange? Draw each rearranged structure below.

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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


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


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CONCEPT: HYDROHALOGENATION

General Reaction:


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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:


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PRACTICE: Provide the mechanism and predict the product of the following reaction.

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CONCEPT: OXYMERCURATION-REDUCTION

General Reaction:

Mechanism:

1. Electrophilic Addition

2. Nucleophilic Substitution (SN2)

3. Reduction (demurcuration)

ORGANIC - BROWN 7E


PRACTICE: Provide the mechanism and predict the product of the following reactions.

a.

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CONCEPT: HYDROBORATION-OXIDATION

General Reaction:

Mechanism:


2. Oxidation

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a.

b.

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CONCEPT: CATALYTIC HYDROGENATION AND WILKINSON’S CATALYST

General Reaction:

PRACTICE: Provide the products for the following reaction.

ORGANIC - BROWN 7E


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.

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CONCEPT: HALOGENATION

General Reaction:

Mechanism:



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CONCEPT: HALOHYDRIN FORMATION

General Reaction:

Mechanism:



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a.

b.

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CONCEPT: SYN VICINAL DIHYDROXYLATION

General Reaction:

EXAMPLE: Predict the product for the following multi-step reaction.

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CONCEPT: WEAK OXIDATIVE CLEAVAGE

Ozonolysis: Ketones + Aldehydes + Formaldehyde

PRACTICE: Predict the products of the following reaction

ORGANIC - BROWN 7E


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


PRACTICE: Predict the products and show the full mechanism for the following reaction

ORGANIC - BROWN 7E


CONCEPT: OXIDATIVE CLEAVAGE

Strong Oxidative Cleavage: Ketones + Carboxylic Acid + Carbon Dioxide

PRACTICE: Predict the product of the following reaction.

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CONCEPT: OXIDATIVE CLEAVAGE

Cleavage of Alkynes: Carboxylic Acid + Carbon Dioxide

EXAMPLE: Predict the product of the following reaction.

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ch.5 + 6 - alkenes and reactions of...

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