Download Alcohols

Alcohols
Condensation Reaction
CH3 – OH + HO – CH3
H2SO4
CH3 – O – CH3 + H2O
two molecules combine to form
larger molecule + water
alcohol + alcohol
ether + H2O
Ethers
-
R
water
alcohol
ether
H-bond acceptor Ono H-bond donor
dipole-dipole interactions
low b.p.
soluble in polar solvents
Ethers
Common nomenclature : name both R groups + ether
1
2
1
3
O
..
propyl
methyl
methyl propyl ether
methyl dimethyl ether
methyl “ether” bunny
propyl people ether
Ethers
Reactions
Formation:
H2SO4
condensation reaction
Peroxide formation:
peroxide
Aldehydes and Ketones
120o
aldehyde
C=O
ketone
carbonyl group
C and O are sp2 hybridized
polar
higher b.p. than alkanes
H-bond acceptor soluble in polar solvents
no H-bond donor lower b.p. than alcohols
Aldehydes and Ketones
Nomenclature
1. Longest chain with C=O is parent
2. Suffix is “-al” or “-one”
3. C1 is always C=O in aldehydes
In ketones, C=O is given lowest number
4. C=O has precedence over -OH
(called “hydroxy”)
4
5
2
3
3
4
2
2-bromo-3-methylbutanal
1
2
3
1
1
3- pentanone
trans3-hydroxy-2-methyl cyclobutanone
Reactions
Reduction
[R] = reducing agent
LiAlH4
NaBH4
H2/Pt
[R]
4
3
1
2
CH3- CH2- CH2- CHO
butanal
[R]
1
3
4
2
2- butanone
CH3- CH2- CH2- CH2-OH
ketone
aldehyde
very polar
:
C=O
:O :
:O : -
C
C+
Nucleophilic addition
-
+
:O :
C
+
+
H
Nu
-
O H
C Nu
H-Nu
H-OH
H-OR
H-NH2
Nucleophilic addition
R
R
..
C=O
..
H+
R
..
R C =O
.. H
R
H+
R
+ H-OH
R
R
..
C=O
..
+ H-OR
+ H-NH2
R
R
..
O
.. H
C
....
O
...... H
H
R N
H
H H H
R
R
C O-H + H+
O-H
hydrate or diol
R
C
R
O-H + H+
O-R
hemi-ketal
R RR
R
+ H+
C O+-HH2O
N
N -H
H2
Schiffs base
Addition of alcohol
H3H
C
H 3C
C O + CH3OH
H+
CH3
H
H3C C OH
ketone + alcohol = hemi- ketal
unstable
aldehyde + alcohol = hemi- acetal
unstable
OCH3
6 CH OH
2
5
O OH
C1
2 OH
3
HO
4 OH
5 OH
6
CH2OH
4 OH
3 2
OH
1
H
OH
b.p. = 150o
6 CH OH
2
5
OH
4 OH
1
3 2 OH
OH
OH
b.p. = 146o
HO
3
6 CH2OH
4 5
OH
2
1
OH
-D-glucose
CH2OH
OH
O
OH
HO
H
more stable
HO
OH
OH
-D-glucose
Nucleophilic substitution
H
H3C C
..
OH
..
..
+ OH
.. - CH3 - CH2
+
H H
H
H
.. O - CH - CH
H+
2
3
H3C C ..
OH
O - CH2 - CH3 H2O
O - CH2 - CH3
H
hemi - acetal
H3C C
O - CH2 - CH3
O - CH2 - CH3
aldehyde + alcohol + alcohol
acetal
condensation reaction
hemi-acetal + alcohol
acetal + H2O
+ H+
acetal propanal +
2 equivalents ethanol
stable
hemi- ketal 2-butanone +
1 equivalent methanol
unstable
Carboxylic acids
1o alcohol
[O]
methanol
H-bond acceptor
H-bond donor
aldehyde
methanal
[O]
carboxylic acid
methanoic acid
-
- +
very high b.p.
2 H-bonds / molecule
Carboxylic acids
Nomenclature
1. Carboxyl group (COOH) always C1
2. Family name is longest C chain with COOH
3. Suffix is “-oic acid”
4. Carbonyl groups (C=O) called “oxo”
Hydroxy groups (OH) called “hydroxy”
Carboxylic acids
4
3
2
1
CH3 – CH2 – CH – C
O
2-ethylbutanoic acid
OH
CH2 – CH3
O
OH
CH2 – CH3
CH3 – CH2 – CH – CH2 – CH – CO2H
6
5
add [O]
4
3
2
1
2-ethyl
4-hydroxy
2-ethyl- 4-hydroxyhexan oic acid
2-ethyl- 4-oxo hexan oic acid
Carboxylic Acids
Chemical properties
= C=O + OH = Bronsted acid H+ donor
HA
H+ + AH+ +
weak acids, small dissociation
Ka = [A-] [H+]
[HA]
Ka  1 x 10-5 pH  2.5 for 1M
Carboxylic Acids
H+ +
H+ +
-
resonance structure
anion stabilized
Carboxylic Acids
acidity also affects solubility
soluble
H-bonding
short chain acids
O
long chain acids
C
OH
benzoic acid
LDF
O
add a strong base (OH-)
C
insoluble
OH
soluble
ion-dipole
Reactions
Acid-base reactions:
O
O
-
+ NaOH
OH
+ H2O
octanoic acid
insoluble
O
O
O
O
O
O- O
O-
sodium octanoate + water
soluble
O
O
O
O
O
O
O
O
O
O
-
O
O
-
O
OO
O -O
O
Na+
O
Reactions
Reduction:
LiAlH4
6
5 4
3
2
1
5-oxo hexanoic acid
1,5- hexanediol
H2/ Pt
NaBH4
5-hydroxyhexanoic acid