Organic 2 Organic Chemistry Wade 69 Ch 7 Structure and Synthesis of Alkenes 2622

ORGANIC - WADE 8E CH.7 - STRUCTURE AND SYNTHESIS OF ALKENES

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ORGANIC - WADE 8E CH.7 - STRUCTURE AND SYNTHESIS OF ALKENES CONCEPT:  ALKENES

□  Alkenes/Alkynes

and 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.

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ORGANIC - WADE 8E CH.7 - STRUCTURE AND SYNTHESIS OF ALKENES 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.

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ORGANIC - WADE 8E CH.7 - STRUCTURE AND SYNTHESIS OF ALKENES CONCEPT:

ELIMINATION AND ZAITSEV’S RULE

□ We often find that an elimination reaction can yield more than one unique alkene as a product. ● The most stable product = ________________

● The least stable product = ________________

Zaitsev’s Rule explains that we will always favor the more substituted, thermodynamically stable product 

□ UNLESS we are using a bulky base. A bulky base promotes the formation of a less substituted, kinetic product 

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ORGANIC - WADE 8E CH.7 - STRUCTURE AND SYNTHESIS OF ALKENES PRACTICE:  Predict

ALL of the products of the following reactions. Label them as either major or minor if necessary.

a.

b.

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ORGANIC - WADE 8E CH.7 - STRUCTURE AND SYNTHESIS OF ALKENES CONCEPT:  DEHYDROHALOGENATION □

The name given to an E2 reaction of an alkyl halide. The major product will depend upon the type of base used.

Mechanism:

EXAMPLE:  Supply the

mechanism and major/minor products for the following dehydrohalogenation reaction:

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ORGANIC - WADE 8E CH.7 - STRUCTURE AND SYNTHESIS OF ALKENES CONCEPT:  ACID-CATALYZED

DEHYDRATION

□  Alcohols are terrible leaving groups, but in the presence of acid, they can be converted into an awesome leaving group

●

The more –R groups on the alcohol, the easier to dehydrate: _________________________________

●

The specific elimination mechanism depends on how easily the molecule will form a ______________________.

E2 Dehydration: 1o Alcohol Mechanism: ● Protonation:

● E2 β-Hydrogen Elimination:

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ORGANIC - WADE 8E CH.7 - STRUCTURE AND SYNTHESIS OF ALKENES CONCEPT:  ACID-CATALYZED

DEHYDRATION

□  Alcohols are terrible leaving groups, but in the presence of acid, they can be converted into an awesome leaving group

E1 Dehydration: 2o and 3o Alcohol Mechanism: ● Protonation:

● Carbocation Formation:

● E1 β-Hydrogen Elimination:

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ORGANIC - WADE 8E CH.7 - STRUCTURE AND SYNTHESIS OF ALKENES PRACTICE:  Provide

the mechanism and products for the following dehydration reactions:

a.

b.

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