chapter 16 aldehydes and ketones i. nucleophilic additions to the carbonyl group 16.1 introduction...
TRANSCRIPT
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Chapter 16 Aldehydes and Ketones I. Nucleophilic additions to t
he carbonyl group16.1 Introduction
Except for formaldehyde, the simplest aldehyde, all aldehydes have a carbonyl group, C=O, bonded on one side to a carbon, and on the other side to a hydrogen. In ketones, the carbonyl group is
situated between two carbon atoms.
H C
O
H R C
O
H R C
O
R'(Ar) (Ar) (Ar)
Formaldehyde Aldehydes Ketones
¼×È© ͪȩ
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16.2 Nomenclature of aldehydes and ketones
In the IUPAC system aliphatic aldehydes are named substitutively by replacing the final e of the
name of the corresponding alkane with al
For example
H C
O
H H3C C
O
H
(Formaldehyde)¼×È© ÒÒÈ©
Methanal Ethanal
(acetaldehyde)
CH3CH2CHO
Propanal
(propionaldehyde)
CH3CH2CH2CHO
Butanal
±ûÈ© ¶¡È©
IUPAC;
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Aldehydes in which the –CHO group is attached to a ring system are named substitutively by adding the suffix c
arbaldehyde.
C
O
H C
O
H
(Benzaldehyde)
±½¼×È© »·¼º»ù¼×È©
Benzenecarbaldehyde Cyclohexanecarbaldehyde 2-Naphthalenecarbaldehyde
2-ÝÁ¼×È©
IUPAC;
CHO
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Aliphatic ketones are named substitutively by replacing the final e of the name of the corresponding alkane with one
C
O
CH3
(ethyl methyl ketone)
2-¶¡Íª
2-Butanone 4-Penten-2-one
4-ÎìÏ©-2-ͪ
IUPAC;
CH3CH2 CH3COCH2CH2CH3
2-Pentanone
(ethyl propyl ketone)
CH3COCH2CH=CH2
1 2 3 4 5
2-Îìͪ
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C
O
CH3
±ûͪ
Acetone Benzophenone
¶þ±½¼×ͪ
CH3
Acetophenone
±½ÒÒͪ
O
CH3
O
(diphenyl ketone)(methyl phenyl ketone)(dimethyl ketone)
4-Ethanoylbenzenesulfonic acid
p-ÒÒõ£»ù±½»ÇËá
2-Methanoylbenzoic acid
2-È©»ù±½¼×Ëá
O
OH H3C
O
(p-acetylbenzenesulfonic acid)(o-formylbenzoic acid)
CHO
SO3H
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Some aromatic aldehydes obtained from natural sources have very
pleasant fragrances.
CHO
OH
CHO
OH
OCH3
CHO
Benzaldehyde(from bitter almonds)
Vanillin(from vanilla beans)
Salicylaldehyde(from meadowsweet)
Ïã²ÝÈ©
¡´ Ö²¡µÐåÏß¾Õ
Ë®ÑîÈ©
¿àÐÓÈÊ
±½¼×È©
Ïã²Ý¶¹
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CHO
CH=CHCHO
Cinnamaldehyde(from cinnamon)
Piperonal(made from safrole;odor of heliotrope)
ºú½·È©
ÓÉ»ÆÕÁÓ;«ÖƱ¸, [Ö²] ÏòÈÕ¿ûÆøζ,[Ö²Îï ]Èâ¹ð , ¹ð Ƥ,
Èâ¹ð È© (3-±½»ù±ûÏ©È©£©
O
O
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16.4 Synthesis of aldehydes1. Oxidation
R CH3OH
N
CrO O
O
HCl PCC
CH2Cl2
R CHO
Aldehyde
CH3(CH2)5CH2OH
CH2Cl2
PCCCH3(CH2)5CHO
Heptanal(93%)
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2 Reduction
H Al
OC(CH3)3
OC(CH3)2
OC(CH3)3Li+
_
Lithium tri-tert-butoxy aluminum hydride
ÈýÊå-¶¡Ñõ»ùÇ⻯ÂÁï®
Reduction reagens;
H Al
CHCH2CH3
CHCH2CH3
CH3
Diisobutyl aluminum hydride
¶þÒ춡»ùÇ⻯ÂÁ
(DIBAL-H)
CH3
Aldehydes from Acyl chlorides;
Aldehydes from esters;
Aldehydes from nitriles;
RCOCl RCHO
RCOCl RCHO
RC RCHON[H-]
[H-]
[H-] H2O
H2O
H2O
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-78 oCR
O
Cl
R
O
COR'
R C N
HAl(CH(CH3)CH2CH3)2 H2O
-78 oC
HAl(CH(CH3)CH2CH3)2 H2O
-78 oC
HAl(CH(CH3)CH2CH3)2 H2O
R
O
H
-78 oCR
O
ORHAl(CH(CH3)CH2CH3)2
H-
R
OAl(i-Bu)2
OR
H
(-OR)R
O
H
+ Al(i-Bu)2H2O
R
O
H
- +
Reduction of Esters to aldehydes
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16.5 Synthesis of ketones
1. Ketones (and aldehydes) by Ozonolysis of alkenes
R
R'
R''
H
1. O3
2. Zn, H2OO
R
R'
O
R''
H
+
Ketone AldehydeAlkenes
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2. Ketones from Friedel-Crafts Acylations
+ RCOClAlCl3 COR
+ HCl
+ COClAlCl3 C
+ HCl
O
+AlCl3 COR
+ HCl
O
R
O
R
O
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3. Ketones from Oxidations of secondary alcohols
R CH
OH
R'H2CrO4
R C
O
R'
H3C CH
OH
CH3
H2CrO4H3C C
O
CH3
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4. Ketones from Alkynes
C C + H2OHgSO4
H2SO4
C C
H
O
A vinylic alcohol (Ï©±û´¼£©(Unstable)
H
C C
OH
H
Keto form
C CH3C CH3 + H2OHgSO4
H2SO4
C CH3C CH3
H
O
A vinylic alcohol (Ï©±û´¼£©(Unstable)
H
H3C C C
O
CH3
H
H
2-Butanone
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5. Ketones from Lithium Dialkylcuprates ( 二烷基酮锂)
R2CuLi + R'CCl
O
Lithiumdialkylcuprate
Acyl chloride
R' C R
O
O
Cl + (CH3)2CuLi-78 oC
O
CH3
(81%)
Hexyl methyl ketoneLithium dimethylcuprate
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6. Ketones from the reaction of nitriles with RMgX or RLi
R C N + R'MgX R
N+ MgX-
R'
H3O+
R
O
R'
R C N + R' Li R
N+ Li-
R'
H3O+
R
O
R'
C N + Ph
N+ MgBr-
PhH3O+
Ph
O
Ph
Ph C N + Ph
N+ Li-
CH2CH2CH2CH3
H3O+
C6H5
O
CH2CH2CH2CH3
C6H5MgBr
n-BuLi
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16.6 Nucleophilic addition to the carbon-oxygen double bond
R
H
O + H-Nu R
H
OH
Nu
Nucleophilic addition
Nucleophilic reagent
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H3C
H
O +
H3C
H
OH
OCH2CH3
Nucleophilic addition(a hemiacetal°ëËõÈ©£©
H-OCH2CH3
H3C
H3C
O +
H3C
H3C
OH
CN
Nucleophilic addition
(a cyanohydrinÇè´¼£©
H-CN
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16.7 The addition of water and alcohols: Hydrates( 水合物 ), Acetals
(缩醛) , and ketals( 缩酮 )
H3C
H
O +
H3C
H
OH
OH
Nucleophilic addition
Nucleophilic reagent
H-OH
Hydrate( a gem-diol)̼ͬ¶þ´¼
Cl3CC
H
O +
Cl3C
H
OH
OH
Nucleophilic addition
Nucleophilic reagent
H-OH
Chloral Hydrate( a gem-diol)̼ͬ¶þ´¼
Trichloroethanal
ÈýÂÈÒÒÈ©
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16.7B Hemiacetals and Hemiketals(半缩醛和半缩酮)
R
H
O +
R
H
OH
OR
Nucleophilic addition
Nucleophilic reagent
H-OR
Hemiacetal °ëËõÈ©
H+
R
H
OH
OR
(unually too unstable to isolate)Aldehyde
R
R
O +
R
H
OH
OR
Nucleophilic addition
Nucleophilic reagent
H-OR
Hemiacetal °ëËõͪ
H+
R
R
OH
OR
(unually too unstable to isolate)
Ketone
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16.7C Acetals and cyclic ketals (缩醛和环状缩酮)
R
H
O +
R
H
OH
OR
Nucleophilic addition
Nucleophilic reagent
H-OR
Hemiacetal °ëËõÈ©
H+
R
H
OH
OR
(unually too unstable to isolate)Aldehyde
HCl
ROH
R
H
OR
OR
an acetal ËõÈ©
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R
R
O +
R
H
OH
OR
Nucleophilic addition
Nucleophilic reagent
H-OR
Hemiacetal °ëËõͪ
H+
R
R
OH
OR
(unually too unstable to isolate)
Ketone
HCl
ROH
R
R
OR
OR
an acetal ËõͪR
R
O +
Nucleophilic addition
Nucleophilic reagent
Ketone
HCl R
R
an ketal Ëõͪ
HO
HOO
O
R
R
an ketal Ëõͪ
O
O
HCl+ H2O
R
R
O +
HO
HO
Cyclic ketals as protecting groups
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16.7D Acetals and cyclic ketals as protecting groups
HO
HO
Cyclic ketals as protecting groups
O
O
OCH2CH3 O CH2OH
LiAlH4 or H2 / Ni HO CH2OH
HCl
O
OCH2CH3
O
O
±ä³ÉËõͪ£¬±£»¤ôÊ»ù
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Synthetic application
HO
HO
Cyclic ketals as protecting groups
O
O
OCH2CH3
HCl
O
OCH2CH3
O
O
±ä³ÉËõͪ£¬±£»¤ôÊ»ù
1. LiAlH4, (CH3CH2)2O
2. H2O
CH2OH
O
O
H+
H2O
OCH2OH
È¥±£»¤»ù
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16.7E Thioacetals and thioketals;硫缩醛和硫缩酮
Aldehydes and ketones react with thiols to form thioacetals and thioketals.
R
H
O +
HSCH2CH3
HSCH2CH3
R
H
SCH2CH3
SCH2CH3
H+
- H2O
Thioacetal
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R
R
O +
R
R
S
S
H+
- H2O
Cyclic Thioketal
HS
HS
Raney Ni
H2
R
R
Zn-Hg, HCl
Clemmensen reduction
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16.8 The addition of derivatives of ammonia
Aldehydes and ketones react with a number of derivatives of ammonia in the general way sho
wn in the following sequence:
R
H
O+N H
H
N
H
H
H
R
O-
(R')(R')
+
N
H
H
R
OH
(R')
N
R
H- H2O (R')
- H+
Nucleophilic addition---Elimination
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16.8A 2,4-Dinitrophenylhydrazones, Semicarbazones, and oximes
Nucleophilic addition---Elimination
O
+ H2N OH
Aldehyde or ketone
N OH + H2O
HydroxylamineôÇ°·
+ H2NNH2
Hydrazine
N NH2 + H2O
An oxime
A hydrazone
H2NNH
Phenylhydrazine ±½ëÂ
N NHC6H5 + H2O
A phenylhydrazone
ph
ë ëê
ë¿
񫉈
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Nucleophilic addition---Elimination
O
Aldehyde or ketone
H2NNH
2,4-Dinitrophenylhydrazine2£¬4-¶þÏõ »ù±½ëÂ
N NHNH + H2O
A 2,4-Dinitrophenylhydrazone2£¬4-¶þÏõ »ù±½ëê
O2N
NO2
O2N
NO2
H2NNHCNH2
O
NNHCNH2
O
+ H2O
Semicarbazide A semicarbazone°±»ùëå Ëõ°±»ùëå
+
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Specific ExamplesNucleophilic addition---Elimination
H3C
H
O + H2N OH
Acetaldehyde
H3C
H
N OH + H2O
HydroxylamineôÇ°·
+ H2NNH2
Hydrazine
C6H5
N NH2 + H2O
Acetaldoxime
Propiophenone hydrazone
H2NNH
Phenylhydrazine ±½ëÂ
C6H5
H3C
N NHC6H5 + H2O
Acetophenone phenylhydrazone
ph
ë ±½±ûͪëê
ÒÒÈ©ë¿
±½ÒÒͪ±½ëê
ÒÒÈ©
C6H5
O
Propiophenone±½±ûͪ
C6H5
H3C
O +
Acetophenone±½ÒÒͪ
O + H2NNHCNH2
O
NHNHCONH2
Cyclohexanone Cyclohexanone semicarbazone
»·¼ºÍª »·¼ºÍªËõ°±»ùëå
+ H2O
Semicarbazide
因为产物都是固体,利用此反应可以鉴定未知有机物。
![Page 31: Chapter 16 Aldehydes and Ketones I. Nucleophilic additions to the carbonyl group 16.1 Introduction Except for formaldehyde, the simplest aldehyde, all](https://reader033.vdocuments.us/reader033/viewer/2022061603/56649dc65503460f94ab9de6/html5/thumbnails/31.jpg)
16.8B Imines
Aldehydes and ketones react with primary amines to form imines.
Nucleophilic addition---Elimination
H3C
H
O + H2N CH3
Acetaldehyde
H3C
H
N CH3 + H2O
Methylamine¼×°·
Acetaldimine
ÒÒÈ©ÑÇ°·ÒÒÈ©
£¨Î÷·ð¼î£©£¨Schiff bases)
![Page 32: Chapter 16 Aldehydes and Ketones I. Nucleophilic additions to the carbonyl group 16.1 Introduction Except for formaldehyde, the simplest aldehyde, all](https://reader033.vdocuments.us/reader033/viewer/2022061603/56649dc65503460f94ab9de6/html5/thumbnails/32.jpg)
16.8C Hydrazones: The Wolff-Kishner reduction
Hydrazones are the basis for a useful method to reduce carbonyl groups (C=O) of aldehydes and ketones to – CH2 – groups, called the Wolff-K
ishner reduction
O H2N-NH2
NaOH+
Triethylene glycol, 200 oC
HOCH2CH2OCH2CH2OCH2CH2OH
C N-NH2 CH2
Hydrazone(not isolated)
+ N2 + H2O
O
CH2CH3
NaOH
Triethylene glycol, 200 oC
HOCH2CH2OCH2CH2OCH2CH2OH
CH2CH2CH3
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16.9 The addition of hydrogen cyanide (HCN) and of sodium bis
ulfite (NaHSO3)
O
R
H (R')
+ HCN
R
H (R')
OH
CNCyanohydrins
ëæ´¼
ÇâÇèËá
Hydrogen cyanide
O
R
H (R')
+ NaHSO3
R
H (R')
OH
SO3Na
Sodium bisulfite Bisulfite addition product
ÑÇÁòËáÇâÄÆ
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Cyanohydrins are useful intermediates in organic
synthesis.
O
H3C
H3C
+ HCN
H3C
H3C
OH
CN
Cyanohydrins
ëæ´¼
ÇâÇèËá
Hydrogen cyanide
HCl, H2OH3C
H3C
OH
COOH
H2SO4
CH3OHH2C
CH3
COOCH3
Hydroxy acid
ôÇ»ùËá
£¬ - Unsaturated acid
CH2 C
CH3
COOCH3
* *n
¾Û±ûÏ©Ëá¼×õ¥2-¼×»ù±ûÏ©Ëá¼×õ¥
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HCN
Cyanohydrins
ëæ´¼
ÇâÇèËáHydrogen cyanide
O
NaHSO3
OH
CN
OH
SO3Na
1) LiAlH4
2) H2O
OH
CH2NH2
- amino alcohol
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16.10 The addition of ylides( 叶立德) : The wittig (魏悌希) reactio
n
O
R
(R')H
+ (C6H5)3P-C
R'''
R''+ -
Phosphorus ylide
Á×Ò¶Á¢µÂ
R
(R')H
R''
R'''
+ O P(C6H5)3
Triphenylphosphine oxide
Èý±½»ùÑõì¢
This reaction, known as the wittig reaction , has proved to be a valuable method for synthesizing alkenes. Discovered in 1954 by Geroge Wittig, then at the University of Tubingen. Wittig was a co-winner of the Nobel prize for chemistry in 1979.
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How to make phosphorus ylide?
Step 1
Step 2
(C6H5)3P: + CH3 Br (C6H5)3P CH3Br -+
Methyltriphenylphosphonium bromide (89%)
(C6H5)3P CH3Br -+
+ C6H5Li or n-BuLi (C6H5)3P CH2:-+
Betaine£¨ÄÚÑΣ©
Phosphorus ylide ì¢Ò¶Á¢µÂ
(C6H5)3P CH2:-+
(C6H5)3P CH2
Resonance structures
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(C6H5)3P CH2:-+
O+ CH2
O- P(C6H5)3+
O P(C6H5)3
CH2 + O P(C6H5)3
Triphenylphosphine
Methylenecyclohexane
(C6H5)3P CHCH3
++
HC
O- P(C6H5)3+
O P(C6H5)3
C + O P(C6H5)3
Triphenylphosphine
O
H
- CH3
CH3
C6H5
H
H
CH3
C
C6H5
H
CH3
H
E-
Z-
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16.11 The addition of organometallic reagents: The reformatsky reaction
Grignard reagent;
RMgX + O R OMgXH3O+
R OH
Organolithium reagent;
RLi + O R OLiH3O+
R OH
Sodium alkynides;
RC CNa + O ONaH3O+
R
OHR
The Nucleophilic Addition of organometallic reagents are as follows
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The addition of an organo zinc reagent to the carbonyl group of an aldehyde or ket
one is called the Reformatsky reaction
O
H2C OZnBrH3O+
The Reformatsky reaction;
BrCH2COOCH2CH3 + ZnBenzene
BrZnCH2COOCH2CH3
Bromoester
H3CH2COOC CH2 OHH3CH2COOC
-Hydroxy ester
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Examples of the Reformatsky reaction are the following:
The Reformatsky reaction;
BrCH2COOCH2CH3 + ZnBenzene
BrZnCH2COOCH2CH3
Bromoester
CH3CHO BrZnCH2COOCH2CH3
+
Similar Grignard reagent
H3O+
CH3CHCH2COOCH2CH3
OH
BrZnCH2COOCH2CH3
H3O+
CH3CCH2COOCH2CH3
OH
CH3C
CH3
O +
CH3
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16.12 Oxidation of aldehydes and ketones
O
H
KMnO4, NaOHO
ONa
O
OH
HCl
or Ag2O, NaOH
O
CH3
KMnO4, NaOH
or Ag2O, NaOHNo reaction
Benzoic acid
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16.12A The Baeyer-Villiger oxidation of aldehydes and ketones
Both aldehydes and ketones are oxidized by peroxy acids. This reaction, called the Baey
er-Villiger oxidation.
O
CH3
Acetophenone
RCOOH
O
O
O
CH3
Phenyl acetate ÒÒËá±½õ¥
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The mechanism proposed for this reaction involves the following steps:
O
CH3
Acetophenone
Phenyl acetate ÒÒËá±½õ¥
+ HO O
O
R
CH3
OH
O O
O
R
H+
CH3
OH
O O
+OH
R
CH3
O
O+
O
OH
R
H
phenyl migration
H3C
O
O + H+
Peroxy acid
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16.13 Chemical and spectroscopic analysis for aldehydes and ketones
16.13A Tollens’test( 托伦测试) (silver mirror test 银镜测试)
R
O
H(Ar)
(H)Ag(NH3)2OH+ R
O
O-(Ar)
(H)+ Ag
Silver mirrorTollen' reagent
Aldehyde or ketones
R
O
R(Ar)
Ag(NH3)2OH+
Tollen' reagent
No reaction
KetonesTollen’s test can distinguish with aldehydes and ketones
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16.13B Spectroscopic properties of aldehydes and ketones
Carbonyl stretching bands of aldehydes and ketones
C=O stretching frequencies
RCHO 1720 cm-1
ArCHO 1695 cm-1
ArCH=CHCHO 1680 cm-1
RCOR 1710
ArCOR 1680
C=CCOR 1665
cm-1
cm-1
cm-1
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Additional problems---Homework
16.24, 16.26, 16.28, 16.31, 16.32, 16.42