Alkenes: OxidationOzonolysis

Dihydroxylation with OsO4

Alkenes: OxidationHydroboration oxidation

Alkenes: OxidationCold, alkaline KMnO4

acidic KMnO4

Polymerization of Alkenes• Polymers are large molecules that

contain a large number of repeating units of a small molecule (monomer).

• Biopolymers are typically synthesized by organisms.

• Synthetic Polymers are made in organic laboratories.

Polymerization of AlkenesAlkenes can be used as a monomeric unit

to form chain-growth polymers

styrene

n

polystyrene

Polymerization of Alkenes

Polymerization of AlkenesFor the polymerization, electrophilic addition reactions can be used.

BF3 F3B

In the initiation step an electrophile (BF3) adds to the alkene to form a carbocation intermediate.

Polymerization of Alkenes

F3B+

F3B

Subsequent propagation steps grow the polymer until all monomers are consumed.

Polymerization of AlkenesTermination can also be accomplished by adding a nucleophile.

F3B

n

Nu

F3B

Nu

n

Polymerization of AlkenesAn alternative way to initiate polymerization is starting with a radical initiator.

RO ORD

(hn) 2 ROradicals

RORO

R RR

The radical adds onto the alkene to form a new radical. Propagation is accomplished via subsequent radical additions.

PREPARATION OF ALKENES-ELIMINATION REACTION

Preparation of Alkenes• -Elimination Reactions• Dehydrogenation of alkanes• Dehydration of alcohols• Dehydrohalogenation of alkyl halides

Dehydrogenation of Alkanes

Dehydration of Alcohols

Zaitsev’s Rule

Dehydrohalogenation of RX

CONJUGATED DIENESADDITION & DIELS-ALDER REACTIONS

Reaction of Conjugated Dienes• undergo two-step electrophilic addition

reactios just as do simple alkenes• 1,2 & 1,4-addition

Reaction of Conjugated Dienes

CH2 CH CH CH3 CH2 CH CH CH3

Less Substituted Double Bond(Secondary carbocation)

More Substituted Double Bond(Primary carbocation)

+

Diels-Alder Reaction: Cycloaddition

REACTION OF ALKYNESADDITION, OXYDATION, & ACIDITY OF TERMINAL ALKYNES

Reactivity of Alkynes

Hydrohalogenation

Hydrohalogenation

Halogenation

Hydration

Hydration of Alkyne & Tautomerism

Draw the ENOL tautomers of the following ketones:

Catalytic Reduction

Oxidation

Acidity of Terminal Alkynes

H C C H + NH2 H C C + H3N

Acidity of Terminal Alkynes

-FIN-