54c) Fill in the blanks.

Cl2FeCl3

Cl Cl

O

CH3CH2CH2COClAlCl3

Zn(Hg)HCl

Cl

1 2

3

f)

CH3ClAlCl3

SO3

H2SO4

SO3H

CO2H

SO3H

KMnO4

1 2

3

j)CH3Cl

AlCl3

CH3

SO3H2SO4

CH3

SO3H

Cl2(excess)FeCl3

CH3

ClCl

SO3H

CO2H

ClCl

SO3H

KMnO4

1 2

34

k)(CH3)2CHCl

AlCl3

NO2

HNO3H2SO4

Cl2FeCl3

NO2ClNO2Cl

Br Br2hvKOCH3

NO2Cl

1 2

345

55d) CH3ClAlCl3 HNO3

H2SO4 O2N

CO2H

O2N

Sn/HClCO2H

H2N

KMnO4

1 2

3

4

f) OCH3CH2COClAlCl3 Br2

FeBr3

O

Br

NH2NH2

-OH

BrBr

NO2

HNO3H2SO4

H2Pd-C

Br

NH2

1 2

34

5

AlCl3

O

CH3CH2CH2COClO

O2NHNO3H2SO4

NH2NH2

-OH

O2N

H2Pd-C

H2N

j) 1

2

34

O

AlCl3

CH3CH2CH2COCl

Cl2

FeCl3

O

Cl

O

Cl

Br

Br2

hvO

Cl

HO

-OH

POC

O

Cl

O

k)1 2

34

5

Oxidation and Reduction

• Alcohols are oxidized to a variety of carbonyl compounds.Oxidation of Alcohols

Oxidation and Reduction

• Recall that the oxidation of alcohols to carbonyl compounds is typically carried out with Cr6+ oxidants, which are reduced to Cr3+ products.

• CrO3, Na2Cr2O7, and K2Cr2O7 are strong, nonselective oxidants used in aqueous acid (H2SO4 + H2O).

• PCC is soluble in CH2Cl2 (dichloromethane) and can be used without strong acid present, making it a more selective, milder oxidant.

Oxidation of Alcohols

Oxidation and Reduction

• Any of the Cr6+ oxidants effectively oxidize 2° alcohols to ketones.

Oxidation of 2° Alcohols

Oxidation and Reduction

• 1° Alcohols are oxidized to either aldehydes or carboxylic acids, depending on the reagent.

Oxidation of 1° Alcohols

Oxidation and Reduction

Oxidation of 1° Alcohols

CH3CH2Cl

AlCl3

Br

Br2hv

KOR

Br2Br

Br

2 NaNH2

58a) 12

34

5

Alkyl Halides and Elimination Reactions

• A single elimination reaction produces a bond of an alkene. Two consecutive elimination reactions produce two bonds of an alkyne.

E2 Reactions and Alkyne Synthesis

Alkyl Halides and Elimination Reactions

• Two elimination reactions are needed to remove two moles of HX from a dihalide substrate.

• Two different starting materials can be used—a vicinal dihalide or a geminal dihalide.

E2 Reactions and Alkyne Synthesis

Alkyl Halides and Elimination Reactions

• Stronger bases are needed to synthesize alkynes by dehydrohalogenation than are needed to synthesize alkenes.

• The typical base used is ¯NH2 (amide), used as the sodium salt of NaNH2. KOC(CH3)3 can also be used with DMSO as solvent.

E2 Reactions and Alkyne Synthesis

Alkyl Halides and Elimination Reactions

• The reason that stronger bases are needed for this dehydrohalogenation is that the transition state for the second elimination reaction includes partial cleavage of the C—H bond. In this case however, the carbon atom is sp2 hybridized and sp2 hybridized C—H bonds are stronger than sp3 hybridized C—H bonds. As a result, a stronger base is needed to cleave this bond.

E2 Reactions and Alkyne Synthesis

Alkyl Halides and Elimination Reactions

E2 Reactions and Alkyne SynthesisFigure 8.9

Example ofdehydrohalogenation

of dihalides to afford alkynes

CH

NaH

b)C

CH3CH2Br

1 2

Alkynes

• Because sp hybridized C—H bonds are more acidic than sp2 and sp3 hybridized C—H bonds, terminal alkynes are readily deprotonated with strong base in a BrØnsted-Lowry acid-base reaction. The resulting ion is called the acetylide ion.

Introduction to Alkyne Reactions—Acetylide anions

AlkynesReactions of Acetylide Anions• Acetylide anions react with unhindered alkyl halides to yield

products of nucleophilic substitution.• Because acetylides are strong nucleophiles, the mechanism

of substitution is SN2, and thus the reaction is fastest with CH3X and 10 alkyl halides.

AlkynesReactions of Acetylide Anions• Steric hindrance around the leaving group causes 2° and 3 °

alkyl halides to undergo elimination by an E2 mechanism, as shown with 2-bromo-2-methylpropane.

• Thus, nucleophilic substitution with acetylide anions forms new carbon-carbon bonds in high yield only with unhindered CH3X and 1° alkyl halides.

AlkynesReactions of Acetylide Anions• Acetylide anions are strong nucleophiles that open epoxide

rings by an SN2 mechanism.• Backside attack occurs at the less substituted end of the

epoxide.

h)Cl2

FeCl3

Cl Cl

NO2

HNO3H2SO4

Br2hv

Cl

NO2

Br

Cl

NO2

KOR

mClPBA

Cl

NO2

OH2O

Cl

NO2

HO

1 2

34

5 6