Download Alcohols

Oxidation of alcohols
1+
1-
2- 1+
1+
1o alcohol
1+
21+
aldehyde
3+
2-
2- 1+
carboxylic acid
[O] = oxidizing agent dichromate
Cr2O72- Cr3+
permanganate MnO4weak oxidizing agent PCC 1o alcohol  aldehyde
oxidation = loss of e- density from C 1. binding O
2. removing H
Alcohols
oxidation of alcohols:
[O] = Cr2O72- or MnO42-
1o alcohols
[O]
aldehyde
[O]
carboxylic acid
[O]
+ Cr3+
+ Cr2O72-
methanol
[O]
methanal
formaldehyde
methanoic acid
formic acid
Alcohols
oxidation of alcohols:
[O] = Cr2O72- or MnO42- or PCC
2o alcohols
[O]
[O]
ketone
[O]
no reaction
Alcohols
oxidation of alcohols:
[O] = Cr2O72- or MnO42- or PCC
3o alcohols
[O]
no reaction
Aldehydes and Ketones
120o
aldehyde
C=O
carbonyl group
C and O are sp2 hybridized
ketone
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
Physical properties
H
.. C O
..
H
polar
+
H
+
-..
:
C O
..
H
higher b.p. than alkanes
H-bond acceptor soluble in polar solvents
no H-bond donor lower b.p. than alcohols
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
Reactions
Reduction:
LiAlH4
H2/ Pt
NaBH4
Alkanes
CnH2n+2
conformations (Newman)
optical isomers
LDF
cyclic
CnH2n
geometric isomers
combustion
halogenation
Alkyl halides
Nucleophilic substitution
1o SN2
transition state
inversion of stereocenter
3o SN1
carbocation
racemic mixture
2o
?
Alkenes
sp2
CnH2n
geometric isomers
Addition reactions
H–X
H – OH
H–H
Br – Br
polymerization
Alcohols
CnH2n+2O
H-bonding
dehydrate
oxidize
condensation
most substituted alkene
1o
aldehyde carboxylic acid
2o
3o
ketone
no reaction
2 alcohol  ether + water
reduction
aldehyde
CnH2nO
 1o alcohol
H2/Pt, NaBH4, LiAlH4
ketone
 2o alcohol
H2/Pt, NaBH4, LiAlH4
CnH2nO
carboxylic acid CnH2nO2  1o alcohol
only LiAlH4