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Alcohols Contain a hydroxyl (-OH) group
RO
H +
Intermolecular forces: dipole-dipole, H-bonding H-bonds between alcohol molecules: high boiling points
H-bonds with water:up to 4-carbon alcohols soluble in water
-OH group can act as a weak base or a weak acid
R OH R O
H
H
R O+ Strong acid+ Strong base
H3CO
H
H3C
O
H
HO
H
alkoxide oxonium ionalcohol
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Alcohol Nomenclature Parent chain = longest chain containing C with -OH
Root name: replacee withol ethane ethanol, butene butenol, etc.
GiveOH the smallest possible number
OH has priority over double bonds, alkyl groups
TwoOH groups -diol; threeOH groups -triol
Add to end of root name (propanepropanediol)
OH
5-methyl-3-hexanol
OHHO
1,2-ethanediol
(ethylene glycol)
antifreeze
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Alcohol Naming Practice
OH
OH
OH
OH
OH
2-propanol
(isopropyl alcohol)
2,4-dimethyl-3-pentanol
4-penten-2-ol3,5-dimethyl-2,4-heptanediol
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Classes of Alcohols
Primary (1) alcohol
Secondary (2) alcohol
Tertiary (3) alcohol
OH
OH
OH
CH3
1-butanol
4-phenyl-2-hexanol
1-methylcyclohexanol
OH C attached to 1 other C
OH C attached to 2 other Cs
OH C attached to 3 other Cs
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Reactions of Alcohols
Reaction with strong bases
alcohol as proton donor (weak acid)
Reaction with strong acids
alcohol as proton acceptor (weak base)
Dehydration
reverse of hydration of alkenes
requires H+catalyst
Oxidation
increase # of C-O bonds
R OH R O
H
H
R O
Strong acid
Strong base
alkoxide
oxonium ion
R OH
- H2O
alkene
H C C CH3
OH
H
H
H
C C
CH3
HH
H
R R'
O
R H
O
aldehyde ketone
orR OH
oxidizing
agent
H+
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Hydration and Dehydration
C C
CH3
HH
H
H2O+ H C C CH3
OH
H
H
H
H+
Hydration and dehydration are in equilibriumCan change [H2O] to favor one reaction or the other
Change Favors
Increase [H2O] Formation of Alcohol (hydration)
Decrease [H2O] Formation of Alkene (dehydration)
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Possible Dehydration Products
The most-substituted alkene product is favored (most stable)
OH
H
OH
H
OHH
OHH+
?
Major
product
Least Hs ondouble bond
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Oxidation of Alcohols Oxidation: increases oxidation number
More C-O bonds (add O) or increases bond order Fewer C-H bonds (remove H)
Needs an oxidizing agent
CrO3, Cr2O72-, MnO4
-
1alcohol
RC
H
O
RC
OH
O
C OHR
H
H
aldehyde carboxylic acid
PCC stops at
aldehyde
oxidizing
agent
oxidizing
agent
+1
+1
-1-2
+1
+1
-2 -2
-2+3+1
+1
0
0 0
CrO3(Cr6+) Cr
3+
,or PCC (pyridinium chlorochromate)
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Breathalyzer Tests
ethanol ethanal
(acetaldehyde)
ethanoic acid
(acetic acid)
CH3 C OH
H
H
CH3 C
H
O
CH3 C
OH
O
+ Cr6+
+ Cr3+
oxidized oxidized
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Breathalyzer Tests
ethanol ethanal
(acetaldehyde)
ethanoic acid
(acetic acid)
CH3 C OH
H
H
CH3 C
H
O
CH3 C
OH
O
+ Cr6+
+ Cr3+
oxidized oxidized
methanol methanal
(formaldehyde)
methanoic acid
(formic acid)
H C OH
H
H
H C
H
O
H COH
O
oxidized oxidized
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RC
R
O
C OHR
H
R
Oxidation of Alcohols
2alcohol
ketone
oxidizingagent
C OHR
R
R
3alcoholoxidizing
agent No reaction
-2+1
0
-2
+20
0
0 0
+1
CH3 C
CH3
O
CH3 C OH
CH3
H
2-propanol propanone
(acetone)
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Cl
O
Naming aldehydes and ketonesParent chain = longest chain containing C=O (carbonyl)
Aldehyde KetonePrefix
Suffix
Numbering
Naming Priority: Aldehydes > Ketones > Alcohols
-OH (alcohol) substituent hydroxy
oxo
e becomesal
C=O is always C #1
(dont have to number it)
oxo
e becomesone
C=O is lowest possible number
(must number it)
H
OOH
3-hydroxy-4-methylpentanal 3-chloro-2-butanone
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Naming Practice
OO
O O
O O
propanedial 2,4-pentanedione
3-oxopentanal
Has both analdehyde and a
ketone
Aldehyde
has priority
Ketone = oxo
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Condensation of Alcohols
Condensation reaction: two molecules
combine to form a larger molecule (+ water)
Catalyzed by acid (H+)
CH3OH H-OCH3
H2SO4
catalyst CH3OCH3 + H2O+
alcohol alcohol ether water+ +
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Ethers
Intermolecular forces:
Dipole-dipole
No H-bonding between ether molecules Lower boiling point than alcohols
Water or alcohols can H-bond to ether oxygen
Somewhat soluble in water and other polar solvents
RO
RR
OH
H
O
H
water
alcohol
H-bond acceptor
No H-bond donor
Two alkyl groups (Cs) bound to oxygen
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Naming Ethers
Common names: name both R groups, add ether
diethyl ether
(anesthetic)O
ethyl ethyl
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Naming Ethers
Common names: name both R groups, add ether
diethyl ether
(anesthetic)
tert- butyl methyl ether
(used as gasoline additive)
propyl people etherO
O O
O
one-eyed, one-horned, flying...
methyltert-butyl
ethyl ethyl
O
CH3
propyl
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O
O
O
H
Reactions of Ethers
Reactions of peroxides: Explosive!
Formation of peroxides
diisopropyl ether
peroxide
Controlled
detonationResulting crater:
3 feet wide,
one foot deep
+ O2
peroxide
O
diisopropyl ether
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R
C
H
O
R
C
R'
O
Aldehydes and Ketones
C=O group called a carbonylgroup
C and O both
sp2hybridized120
120
aldehyde ketone
R
CH
O
+
R
CH
OVery polar C=O bond
Higher boiling point than alkanes
H-bond acceptor
Soluble in polar solvents
No H-bond donor
Lower boiling point than alcohols
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C4H10O Isomers
OHOH
OH OH
OO
O
1-butanol 2-butanol
2-methyl-2-propanol 2-methyl-1-propanol
diethyl ether methyl propyl ether isopropyl methyl ether
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C5H12OIsomers
OH
OH
OH
OH
OH
OH
OH
OH
1-pentanol 2-pentanol 3-pentanol
2-methyl-1-butanol 3-methyl-2-butanol 3-methyl-1-butanol
2-methyl-2-butanol 2,2-dimethyl-1-propanol
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C5H12OIsomers
O O O
OOO
butyl methyl ether tert-butyl methyl ether sec-butyl methyl ether
isobutyl methyl ether ethyl propyl ether ethyl isopropyl ether
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C4H8O Isomers
O
O
O
butanal 2-butanone
2-methylpropanal
C H O I
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C5H10O Isomers
O
O
O
O
O
O
O
pentanal 2-pentanone 3-pentanone
3-methylbutanal 3-methyl-2-butanone
2,2-dimethylpropanal 2-methylbutanal
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Reactions of Aldehydes and Ketones
Oxidationof aldehydes to carboxylic acids
CrO3, MnO4-
Reductionof aldehydes and ketones to alcohols
Decrease C-O bonds, increase C-H bonds
Reducing agents: LiAlH4, NaBH4, H2/Pt
OHH
O
propanal 1-propanol
CH3CH2CHO CH3CH2CH2OH
LiAlH4
O OH
NaBH4
2-methyl-3-pentanone 2-methyl-3-pentanol
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Reduction of Aldehydes/Ketones
O
O OH
OH
O
3-oxopentanal 1,3-pentanediol
LiAlH4
NaBH4
cyclohexanone cyclohexanol
H2/Pt
OH
OO OH OH
pentanedial 1,5-pentanediol
C b li A id N l t O
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Carboxylic Acid Nomenclature
Parent chain: longest containing carboxyl group (COOH)
Name of parent: replace e with oic acid
Numberingstarts at carboxyl carbon
Priority: Carboxylic acid > aldehydes > ketones > alcohols
hydroxysubstituent
oxosubstituents
OH
O
trans-3-methyl-2-hexenoic acid
(human armpits)
OH
O O
3-oxobutanoic acid
(diabetes)
HO OH
O O
propanedioic acid
(apples)
R C
O
O H
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Carboxylic Acid Reactions
Reduction to 1alcohols
Only LiAlH4reduces carboxylic acids
(not NaBH4or H2/Pt)
butanoic acid 1-butanolOHOH
O LiAlH4
butanoic acid
OH
O NaBH4
or H2/PtNO RXN
OH
O
Reactant remains
unchanged
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What are the products?
3-oxo-4-pentenoic acid
LiAlH4
H2/Pt NaBH4
OH
OOH
OH
OO
OH
OOH
OH
OH
3-hydroxypentanoic acid
4 pentene 1 3 diol
3-hydroxy-4-pentenoic acid