54c) fill in the blanks
DESCRIPTION
54c) Fill in the blanks. 1. 2. 3. f). 2. 1. 3. 1. 2. j). 4. 3. 1. 2. k). 4. 5. 3. 1. 2. 55d). 3. 4. 1. 2. f). 3. 4. 5. j). 1. 2. 3. 4. 1. 2. k). 3. 4. 5. Oxidation and Reduction. Oxidation of Alcohols. - PowerPoint PPT PresentationTRANSCRIPT
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) CH3Cl
AlCl3 HNO3
H2SO4 O2N
CO2H
O2N
Sn/HClCO2H
H2N
KMnO4
1 2
3
4
f) OCH3CH2COCl
AlCl3 Br2
FeBr3
O
Br
NH2NH2
-OH
BrBr
NO2
HNO3H2SO4
H2
Pd-C
Br
NH2
1 2
34
5
AlCl3
O
CH3CH2CH2COCl
O
O2NHNO3
H2SO4
NH2NH2
-OH
O2N
H2
Pd-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
3
4
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
Alkynes
Reactions 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.
Alkynes
Reactions 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.
Alkynes
Reactions 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
HNO3
H2SO4
Br2hv
Cl
NO2
Br
Cl
NO2
KOR
mClPBA
Cl
NO2
OH2O
Cl
NO2
HO
1 2
34
5 6