Download Chapter 16 Aldehydes and Ketones I: Nucleophilic Addition to the

Chapter 16 Aldehydes and
Ketones I: Nucleophilic
Addition to the Carbonyl
Group
ORGANIC CHEMISTRY
Chapter 16
16.1 Introduction
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Chapter 16
Aldehydes and ketones contain an acyl group bonded
either to hydrogen or to another carbon.
O
RC
Acyl group 酰基
H
Formaldehyde
δ−
C O
120
Carbonyl group 羰基
O
C
O
C
H
120
δ+
sp2
O
C
R
H
R
R
RCHO
RCOR'
General formulas General formulas
for an aldehydes for a ketones
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16.2 Nomenclature of Aldehydes and
Ketones
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Aldehydes are named by replacing the terminal –e of
the corresponding alkane name with –al.
The longest chain selected as the base name must
contain the –CHO group, and the –CHO carbon is
always numbered as carbon 1.
O
H C H
CH3
O
C H
Ethanal
(Acetaldehyde)
O
ClCH2CH2CH2CH2 C H
Methanal
(Formaldehyde)
5-Chloropentanal
CH3CH2
O
C H
Propanal
(Propionaldehyde)
O
C6H5CH2 C H
Phenylethanal
(Phenylacetaldehyde)
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For more complex aldehyde in which the –CHO group
is attached to a ring, the suffix -carbaldehyde is used.
CHO
CHO
Benzenecarbaldehyde Cyclohexanecarbaldehyde
(benzaldehyde) 苯甲醛
环己烷甲醛
CHO
2-naphthalenecarbaldehyde 2-萘甲醛
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Ketones are named by replacing the terminal –e of the
corresponding alkane name with –one.
The chain selected for the base name is the longest one
that contains the ketone group, and the numbering
begins at the end nearer the carbonyl carbon.
O
CH3CH2CH2 C CH2CH3
3-Hexanone 3-己酮
(common name: Ethyl propyl ketone)
O
O
CH3CH CHCH2CCH3
4-Hexen-2-one 4-己烯-2-酮
O
CH3CH2CCH2CCH3
2,4-Hexanedione 2,4-己二酮
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Some ketones have common names that are retained in
the IUPAC system.
O
CH3 C CH3
O
O
C CH3
C
Acetone 丙酮
Acetophenone 苯乙酮 Benzophenone 二苯甲酮
propanone
1-phenylethanone
diphenylmethanone
(dimethyl ketone) (methyl phenyl ketone)
(diphenyl ketone)
When RCO- group are named as substituents, they are
called alkanoyl or acyl groups.
O
R C
Acyl
酰基
O
HC
Formyl
甲酰基
O
CH3C
Acetyl
乙酰基
O
C
Benzoyl
苯甲酰基
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If another functional groups or a –CHO are present
and the doubly bonded oxygen must be considered a
substituent, the prefix oxo- is used.
O
O
CH3CH2 C CH2CHO
3-Oxopentanal
3-氧代戊醛
CH3CH2 C CH2CH2CO2H
4-Oxohexanoic acid
4-氧代己酸
O
CHO
2'-Oxocyclohexanecarbaldehyde
2'-氧代环己烷甲醛
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16.3 Physical Properties
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Molecules of aldehyde (or ketone) cannot hydrogen
bond to each other.
They rely only on intermolecular dipole-dipole
interactions and therefore have lower boiling points
than the corresponding alcohols.
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Aldehydes and ketones can form hydrogen bonds with
water and therefore low molecular weight aldehydes
and ketones have appreciable water solubility
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16.4 Synthesis of Aldehydes
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16.4A Aldehydes by Oxidation of 1°
Alcohols
RCH2OH
PCC
RCHO
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16.4B Aldehydes by Reduction of Acyl
Chlorides, Esters, and Nitriles
RCO2H
LiAlH4
RCHO
OC(CH3)3
Li
H Al OC(CH3)3
OC(CH3)3
Lithium tri-tert-butoxyaluminium
hydride
LiAlH(O-t-Bu)3
LiAlH4
RCH2OH
CH2CH(CH3)2
H Al CH2CH(CH3)2
Diisobutylaluminium hydride
i-Bu2AlH or DIBAL-H
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O
(1) LiAlH(O-t-Bu)3 , 78°C
R C Cl
(2) H2O
O
R C H
O
R C OR'
O
R C H
R C N
(1) DIBAL-H, hexane, 78°C
(2) H2O
(1) DIBAL-H, hexane,
(2) H2O
COCl
+ H2
Pd-BaSO4
O
R C H
CHO
S-quinoline
Rosenmund reduction
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16.5 Synthesis of Ketones
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16.5A Ketones from Alkenes, Arenes,
and 2° Alcohols
Ketones (and aldehydes) by ozonolysis of alkenes —
(1) O3, (2) H2O/Zn
Ketones from arenes by Friedel-Crafts acylations —
RCOCl or (RCO)2O/AlCl3
Ketones from 2° alcohols by oxidation — H2CrO4
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16.5B Ketones from Alkynes
R C CH + H2O
HgSO4
H2SO4
O
R C CH3
O
RC CH2
R C CH3
OH
A vinylic alcohol
(unstable)
Ketone
Enol form 烯醇式
Keto form 酮式
Keto-enol tautomerizations
烯醇式－酮式互变异构
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16.5C Ketones from Lithium
Dialkylcuprates
O
R C Cl + R'2CuLi
O
C Cl + (CH3)2CuLi
O
R C R' + R'Cu + LiCl
Et2O
78°C
O
C CH3
(81%)
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16.5B Ketones from Nitriles
R'MgX
N MgX
R C R'
H3O+
O
R C R'
R C N
R'Li
N Li
R C R'
H3O+
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