第七章碳正离子1

引言

碳正离子的生成碳正离子的结构碳正离子的稳定性碳正离子的反应非经典碳正离子 1962年,Olah发现: 1962年 ,Olah发现:

(H3C)3C F

SbF3

(CH3)3C+SbF6-

用NMR和CNMR检测到. NMR和 CNMR检测到.

第七章碳正离子（ａｂｃｔｏｓＣ碳正离子（ｒｏａｉｎ）

1 正碳离子的生成：

1) 反应物直接解离: 反应物直接解离:

Ph CH Cl Ph

Ph2CH

X=H:

CH3 H3C C H CH3 AlCl3

CH3 + H3 C C CH3 HAlCl3-

CH3COF

BF3

CH3CO

BF4

X=OTs酯类衍生物:

CH3 H3C C OTs CH3 CH3 H3C C CH3 + OTs-

X=F, Cl, Br, I:

CH 3 H 3 C C Cl CH 3 AlCl 3 CH 3 H3 C C + CH 3 AlCl4-

X=OCOZ,其中Z=Cl, Br, I

R R C OCOCl R R R C R

X=H2O or ROH

R O R'

+ Cl + CO2

H+

H R O R' +

R+ + R'OH

推动力为失去二氧化碳氯亚磺酸酯也属于此类:

R R C OSOCl R R R C R + Cl+ SO2

R OH

ROH2

H2O

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X=CO

COOH H+ + COOH2 CO+ + H2O

2) 质子或其它阳离子对不饱和键的加成

C Z H C ZH

Z: O,C,S,N

X=CO2

RCOOAgBr2 R+ + Br+

CO +

AgBr

CO2

形成非经典碳正离子: 形成非经典碳正离子:

3) 由其它正离子转化而生成

H+ + H Cl H+ +

NH 2

NaNO 3 HCl

H Ph3CSbF6 SbF 6

2 . 正碳离子的稳定性： 1）电子效应的影响 A CH3 3C > CH3 2CH > CH3CH2 > CH3 σ- p超共轭效应：

B 烯丙型正碳离子：

CH2 CH CH2 CH CH2

p-π共轭

电子离域

CH2

正电荷分散程度大

共轭体系的数目越多，正碳离子越稳定：

CH2 CH 3C

+ + + Ph3C > Ph2CH > PhCH2

CH3 CH2

CH 2 CH 2CH

CH2 CHCH2

CH2

> O 2N

CH2

(CF3)3C+

极不稳定

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C 乙烯型正碳离子： C原子进行sp2杂化， p轨道用于形成π键，空着的是sp2 杂化轨道，使正电荷集中。苯基正离子：结构同乙烯型正碳离子，正电荷集中在sp2杂化轨道上。

此二类正碳离子稳定性极差。

2）. 芳构化效应

3）空间效应

CH3 Cl

+ CH 3

Cl-

(C6H5)3C

H H

(C6H5)3CH +

张力增加，不稳定

稳定性比(C6H5)3C+ 高1011倍

4）溶剂效应：

1) 极性溶剂的诱导极化作用，利于底物的解离。 2) 极性溶剂使正碳离子稳定：

4 碳正离子的反应

与亲核试剂作用---具有电子对的物质结合（Lewis酸碱反应）脱去氢离子生成烯烃重排为更稳定的碳正离子加成反应

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SN 反应 1 与亲核试剂作用

R+ + Y-

R-Y

可能是OH-、卤离子或任何其它阴离子；也可能是带有电子对的中性物种，在后一种情况下，产物是带电荷的。

一 SN1 反应

C Cl

-L-

C+

Nu-

+ Nu

1 烃基结构的影响 2 离去基团的影响 3 溶剂的影响 4 亲核试剂

的影响

（二）

Ｓ反应的立体化学及邻基参与问题Ｎ

OCH3

CH3OH

Neighboring-group participation

I I OH HCl Cl

卤原子参与

※

R C6H5CH(Br)CH3

C6H5CHCH3

27%构型翻转，73%外消旋化

构型保持的取代

Br H H3 C CH3 C C H OH

H C C CH3 OH HBr H H 3C

HBr

Br H H 3C

Br C C

C C

CH3 H Br

H Br H CH3

H3C

C H

NaOH H2O

H CH3 Br + H 3C

H3C

C H

O-

（构型保持）

H H3C

C C

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硫芥和氮芥

CH3 C C H H OH 2 H Br H H3C Br or Br C C H Br ＲＳ２３二溴丁烷，－，－（内消旋结构）

Ｃ－ＨＣ２ＳＣ２Ｈ－ｌｌＣ２Ｈ－－ＨＣ２Ｃ芥子气

CH3

ＲＳＣ２Ｈ－－－ＨＣ２Ｘ一个硫芥

Br H C C H 3C

H CH3 OH2

Br H C C H H 3C CH3 Br or Br

ｌＲＣＳｒｔ－ｉｉｉｇａｅｌｍｔｎＲ－ＨＣ２ＣＳＣ２Ｈ－ｌＨＣＣ２Ｈ２

ＲＲ和ＳＳ２３二溴丁烷，－，－，－

ＨＯ２ｆｓａｔＣｌＲＣ２ＨＯＳＨＣ２Ｈ＋ＨｌＣＲＣ２ＨＯ２ＳＨＣ２Ｈ

硫原子邻位促进作用示例

Cl S HOAc

S Cl HOAc

氮原子邻位促进作用

OAc S + HCl

R R'

N CH2CH2 Cl

R N H2C

R' Cl H2O R CH2

N CH2CH2 OH

CH3

C2H5 C H S S 2 5 HCl H3C C CH2 C C OH H H H2 Cl

H2 H3C CH C SC2H5 Cl

Cl N C2H5 CH2 Cl

N CH C2H5 2

N C2H5

环大小的效应

环的大小对环铵盐形成速率的影响（25℃，水）

Br (CH2)n NH2 (CH2)n + NH2

环的大小对环锍盐形成速率的影响（100℃，20%的二氧六环水溶液）

Cl (CH2)n S C6H5 (CH2 )n + S C6H5

2 3 4 5 6

环原子数

3 4 5 6 7

环生成的相对速率

1 0.014 833 14 0.027

2 3 4 5 1-氯己烷

环原子数

3 4 5 6

环生成的相对速率

1.0000 0.0053 0.2000 0.0170 0.0096

M.I.Page, Chem.Soc.Rev., 2,295(1973)

S.Winstein, J.Am.Chem.Soc.,75,147(1953)

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-OBs对溴苯磺酸基

X OBs

对溴苯磺酸环己基酯的相对反应速率（75 ℃，乙酸）

反应相对速率

X=H X = trans-Cl cis-Cl X = trans-Br cis-Br X = trans-I cis-I 1 4.8

ktrans/kcis

10-4 1.3 10-4

0.10 1.2 1.2 4.3

10-4 103 10-4

800

106

芳基参与

H H H3 C C C CH 3 HOAc OTs

H3C AcO H

H C C H CH3

C H H3C

CH3 OAc

H H3C C

H C CH3 OTs

H H3C

HOAc

H CH3

CH3 H C H H3C C OTs

HOAc H3C

H C C CH3 H

H3C AcO H C C H CH3 H

AcO

C H H3C

CH3 OAc

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C H H3C

CH3 H C OTs

HOAc

芳基的迁移

H H3C AcO C C CH3 H

H H3 C C CH3 H C OAc

H H 3C

CH3 H

S，S-相同化合物

H H C2 H5 C C CH3 OTs

H C2H5

H CH3

C2 H5

H C C H CH3

TsO HOAc

H H H3C C C CH3 OTs

C H H3C O S O

C O

外消旋体

H CH3

H C H C2 H5 C CH3 + OAc C2H5 AcO H C C H CH3

C7H7

Classical Carbocation

涉及非经典碳正离子的邻基参与

(CH3)3C+

C+

CH2

CH2CH2

Nonclassical Carbocation

+ CH5

非经典碳正离子的产生

7 5 1 4 3 2

Cl+

反－7－原冰片烯基对甲苯磺酸酯实验表明：在乙酸中的溶剂解的速度比相应的饱和化合物大 1011倍.产物构型保持.

OTs HOAc

OAc

非经典碳正离子

TsO H H OTs

+ HOTs

TsO

-TsO

AcO

AcOH

Ts = CH3

SO2

溶剂解反应相对速率

2电子3中心体系

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非经典碳正离子中间体: 非经典碳正离子中间体:

H CH3 OH NaBH4

OTs NaOCH3 CH3OH H OCH3

H O PNB = C NO2

OPNB H3C

OPNB H3C H3C

OPNB

k=1.0

104

H Cl

1011

1014

反应相对速率 1.0 （140℃,二氧六环/水）

13.3

148

Br AgOAc HOAc

Br C2H5OH KOAc

OC2H5

SbF6

OAc

芳香环稠合的邻位作用

SbF6

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(H3C)2C Cl (H3C)2C Cl

(H3C) 2C Cl

OBs

BsO

H3C 1.0 (H3C)2C Cl

CH CH3 17.8 (H3C)2C Cl 157

2>3>1

CH3

H3C

CH3

172

37.1

相对溶解速率比较

OTs

TsO

2)σ键参与的非经典正碳离子

D D

D OTs H D HCO2H HCO2 K

O OCH H

exo-

OBs

HOAc

OAc AcO

D D

endo-

H OBs

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7 5 6 H2C 1 2 2 4 3 3 4 6 H2C

7 1

H H

CH C

∗ CH

HOAc

AcO

∗

+ ∗

OAc

O O CH3COH or HOCCH3

H迁移

HOAc C

OAc AcO

+ ∗ OAc

∗ C H H

AcO ∗

再如：

取代基效应对2-降冰片对甲苯磺酯上exo/endo反应速率比值

R R X 181a 16a 3.7a 0.48a 0.37a kexo/kendo

CH3

部分参与

无δ键参与

CH3 Y CH2Br exo(X = OTs, Y = H) endo(X = H, Y = OTs) CO2CH3 F CN X Y exo(X = OTs, Y = H) endo(X = H, Y = OTs) R H CO2CH3 CN

在经典的碳正离子反应中也广泛存在邻基参与，以后各章加以讨论

100b 1.2b 1.1b

返回目录

a：25℃,二氧六环 – 水 b: 乙醇 – 水

亲电加成反应

Br+ H2C C H CH2X H2C Br C H X CH2 Br H2C Br X C H CH2 Br

CH2 C CH2I +Br2 H

H2C Br

C H

CH2 H2C Br

H C Br

CH2

X H2C Br C H CH2 Br H2C

X H C CH2

CH2 C CH2I H

Br+

I H2C Br C H CH2 Br I H2C Br

I C H CH2 Br

Br Br

X=OR,NHR,NH2,NR2,Cl,Br,I

I H2C Br C H CH2 Br H2C Br H C Br

CH2

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CH2 Br

H2C

C CH2OR +Br2 H

H2C Br

C H

H2C Br

H C Br

CH2

H2C C H CH2NHR Br+ H2 C Br C H

HR N CH2 Br NHR CH2 H2C Br

NHR C H CH2 Br

H2C

C CH2OR H

Br+

R O H2C Br CH CH2 Br H2C Br

OR C H CH2 Br

H2 C Br

HR N C CH2 H Br

H2 C

H C

Br Br

R O H2C Br C H CH2 Br H2C Br

OR H C Br CH2

Cl2

H Cl H OOC COO-

OOC

COO-

O H C C O

Cl H COO-

Cl Cl H C C H OOC COO-

H H H H 3C H+

+ +

H CH

3 OH-

H 3C H CH 3

H H 3C OH

H CH3

H HOOC

H COOH

Cl2

H Cl H HOOC COOH

CH3

H3C

C C

Cl H

HOOC Cl

H Cl H C C COOH COOH HOOC Cl

H H 3C OH

H CH3 H H 3C H CH 3 OH

COOH

Br2

O O

二与不饱和化合物的反应

COOH

Br2

COOH

CH3

HO O

(CH3)3C+

CH2

(CH3)3CCH2 C+

CH3

Br O

H C(CH3)3

Ι Br

COOH I O O

(CH 3)3C +

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快

慢

H+

Ingold 提出分速率因素（f）的概念，即一取代苯（PhY）进行亲电取代反应时，环上指定位置的反应速率（ ko , km , kp）与苯环（PhH）上的一个位置的反应速度（ kH ）的比值。由于

同理

fm =

k PhY 6 % 间位异构体 × × k PhH 2 100 %

kPhH = 6k H

(

所以

k H = k PhH

k f0 = 0 = kH

k PhY ) × (%邻位异构体） 100 k 6 %邻位异构体 2 = PhY × × k PhH k PhH 2 100 6

fp =

k PhY 6 % 对位异构体 × × k PhH 1 100 %

三消去反应

E: H+ -+OR2

Nu: -Hal, -OSO2Ar, -+NR3, -+SR2, -OCOR, -OAr, -OR, -CN -OH (-O+H2)

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Mechanism

Reaction kinetics:Reaction rate =k·[RNu] Substituent effects: The formation of carbocation intermediate is rate-controlling step. Carbocation intermediate is stabilized by EDGs. Ionization is favored by a good leaving group. Solvent effects: Carbocation is solvated by polar solvents of high ionizing strength. Base: Playing no role in the rate-determining step, however, bulky and stronger bases favor the E1 path over the SN1 path. Isotope effects: PKIEs for heavy-atom effects.SKIEs for β-H effects

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四** 碳正离子的重排反应----Nucleophilic Rearrangement ( Carbon cation rearrangement ) 1 Wagner-Meerwein rearrangement

CH3 CH3 C CH2OH CH3 H+

Cl Cl

CH3 CH3 C CH2OH2 CH3

Cl-

CH3 CH3 C CH2 CH3

CH3 C CH2CH3 CH3

CH3

Cl C CH2CH3 CH3

H2O

CH3C=CHCH3 CH3

反应机理：

Demyahov 重排

HNO2

CH3CH2CH2NH2

+ H2CH2CH3C N N

-N2

+ CH3CH2CH2+ 1,2-亲核重排 CH3CHCH 3

H2O

OH CH3CHCH3

+ CH3CHCH3

Cl-H+

Cl CH 3CHCH 3

CH3CH

CH2

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CH2NH2 HNO2

CH2+

H2O H+ H+

CH2OH 32%

2 Pinacolic Rearrangement

CH3 CH3 CH3 CH3 H+ CH3 C C CH3 CH3 C C CH3 H2O OH +OH2 OH OH

CH3 CH3 C C CH3 OH CH3

H+ 2%

NH2 HNO2 N2

H2O H+

OH 58%

H2O H+

CH3 CH3 C C CH3 +OH CH3

CH3 CH3 C C CH3 O CH3

H2O H+

CH2=CHCH2OH

The stable cation formed superior

OH OH (CH3)2C C Ph Ph OH (CH3)2C C + Ph Ph

（较稳定） 1,2-迁移

OH OH

-H+

Phenyl group move first

H2O

(CH3)2C C Ph Ph

CH3 H3C C C Ph OH Ph +

-H+

PhHC CHPh OH OH

H+

PhHC

CHPh OH

CH3 H3C C C Ph O Ph

（主要产物）

Ph2CH CH +OH

H+

Ph2CH CH O

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Ph H3C C CH2I OH

HgO

H3C C CH2Ph OH+

-H+

CH3 3 CH H3C C C CH3 O

CH 3 3 CH

H+

O (CH3)3C C CH3

CH3 3 CH H3C C C CH3 OH

H3CC CH2Ph O

CH3CH3 H3C C C CH3 OH NH2

CH3CH3

H+

CH3CH3

HNO2

1,2迁移

H3C C C CH3 OH N N +

-N2

H3C C C CH 3 O

H3C C +C CH3 O H

CH3 3 CH H3C C C OH

-H+

CH3CH3 H3C C C+ CH3 OH

OH CH3 CH3

(CH3)3C C CH3

H3C C C CH3

CH3 O CH3

CH3

H3CC C CH3

1 Beckmann Rearrangement

R C N R' OH

C N

O R

C N

R' H

OH mp147

UV light

C N

C6H4OCH3 -p

PCl5

Et2O, -10

Ph H mp171

C N

C6H4OCH3

Ph C N

CH3 OH

PCl5 ethyl ether

O Ph

C N

CH3 H

Ph C N HO

C6H4OCH3

PCl5 Et2O, -10

Ph H

C N

O C6H4OCH3 -p

mp117

mp156

反应机理

OH 2 -H2O R' C=N-R H2O

+ +

O2N

Ph N Br OH PCl5

O2N

NHPh H2O

O2N

COOH Br PhNH2

R' C=N R

H+

R' C=N R

O2N

Ph N OH Br PCl5

O2N

O2N NHCOPh H2O Br

NH2 Br

PhCOOH

R' C=N-R

R'-C R' C=N-R HO

N-R

H2O

-H

O R'-C-NHR

CH3 C N HO

C2H5 C CH2C2H5 H

H2SO4 Et2O

CH3CONH

C2H5 C CH2C2H5 H

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2 Baeyer-Villiger Rearrangement

O CH3 C Ph CF 3CO3H

CH2Cl2

O CH3 C OPh

O CF 3COOH

CH3

OH CH Cl 2 2 C Ph

OH CH3 C Ph CF 3COOH + O

OH CH3 C Ph CF3C O O OH

O CF 3CO3H

CH3COOEt

O O

OH CH3 C OPh +

CF 3COOH

O CH3 C OPh

O * CH3 C CH Ph CH3 PhCO3H CHCl3 O CH3 C OCH Ph CH3

CH3CH=CH2

anhydrous AlCl3

PhCH(CH3)2

O O CF 3CO3H CH3 C OC(CH3)3 CH3 C C(CH3)3 CH2Cl2

PhCH(CH3)2

Na2CO3/H2O 100

O Ph C

O CF 3CO3H PhO C CH2Cl2

CH3 + Ph C OOH H PhOH CH3

CH3COCH3

3 过氧化物的重排------异丙苯氧化重排 + CH3CH=CH2

CH3 CH3 + H+ PhC O OH H3C C O OH2 CH3

AlCl3

CH(CH3)2

O2 自动氧化

1,2-亲核重排反应的立体化学

_H O 2

CH3 H3C C O Ph +

CH3 + H3 C C O Ph

H2O

OH CH(CH3)2

-H+

CH3 H3C C O Ph +OH2

C-O键断裂

( 95 ％光学纯度）

O + (CH3)2C=OH

质子转移

OH + (CH3)2C=O

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Ph H CH2NH2 Et

NaNO2 HClO4,H2O

OH CH2Ph Et

HO Et

CH2Ph

氢迁移键旋转

氢迁移

外消旋体

其他重排反应

H3C C C H H

CH2

H3C C H

C H

CH2

Nu-

Cl C6H5 C H C H CH 2 -Cl C6H5 C H

C H

CH2

Cl-

Nu H3C C H C H CH2

C6H5 C

H C H CH 2Cl

CH3

H+

CH3

A C B C H C+ A B +Nu-NuA C B C H C

B A

H+

1,4迁移

(Z)

(E)

1,2-亲核重排

CH3 CH3

-H+

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HO CH3 + CH3COOH

H2SO4

CH3 OCOCH3

H3+ O OH OH

HO CH3

H2SO4

H2+O CH3

CH3 +

CH3

CH3 +

CH3COOH

CH3

-H+ + OCOCH3 H

OH + Me2CHCHO CH3 H+ H3C O

Ph Ph

RCO3H

Ph Ph

H3C + H OH

H3C

-H+

H3C

+H+ -H2O

O O Ph Ph

O H

O Ph Ph + RCO2H

H+

+ Me2CHCHOH

OH + H3 C

H O +

H3C

OH + H

H3C

-H+

OH+ Ph Ph

Ph + Ph

OH Ph Ph +

CH2OH

1.PhCO3 H 2.HO-/H2O

HO O

CH3

H2SO4

CH3

Br CH3OH CH3CHCH CH2

CH3CH CHCH2OCH3

CH3 + HCl

CH3

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OH H2C CHCH CHCH3 + H2O H2SO4 H3C HC CH CH CH3

H3C CH3 CH3 H2SO4 H2C C CH2CH2CH2 C CH2 H3C

CH3 +

H3C H3C

CH3

CH3CH CH OCH3 + H2O

HCl

CH3CH2CHO +CH3OH

O CH3COCH3

HC C OCH3 + H2O

O NaOH OC2H5

O + HOC2H5

OH CH3

O NaOH

O 2CH3CCH3

H3 C C CH2 CCH3

O NaOH

O HO C CH 2 CH CH3

O NaOH

CCH 2CHCH 3

O OH NaOH

O CH3 O CH3ONa H3C

O CH3 O

H3C

OH H3C C CH CH2 C N

CH3ONa

O CH3CCH2CH2C N

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引言

碳正离子的生成碳正离子的结构碳正离子的稳定性碳正离子的反应非经典碳正离子 1962年,Olah发现: 1962年 ,Olah发现:

(H3C)3C F

SbF3

(CH3)3C+SbF6-

用NMR和CNMR检测到. NMR和 CNMR检测到.

第七章碳正离子（ａｂｃｔｏｓＣ碳正离子（ｒｏａｉｎ）

1 正碳离子的生成：

1) 反应物直接解离: 反应物直接解离:

Ph CH Cl Ph

Ph2CH

X=H:

CH3 H3C C H CH3 AlCl3

CH3 + H3 C C CH3 HAlCl3-

CH3COF

BF3

CH3CO

BF4

X=OTs酯类衍生物:

CH3 H3C C OTs CH3 CH3 H3C C CH3 + OTs-

X=F, Cl, Br, I:

CH 3 H 3 C C Cl CH 3 AlCl 3 CH 3 H3 C C + CH 3 AlCl4-

X=OCOZ,其中Z=Cl, Br, I

R R C OCOCl R R R C R

X=H2O or ROH

R O R'

+ Cl + CO2

H+

H R O R' +

R+ + R'OH

推动力为失去二氧化碳氯亚磺酸酯也属于此类:

R R C OSOCl R R R C R + Cl+ SO2

R OH

ROH2

H2O

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X=CO

COOH H+ + COOH2 CO+ + H2O

2) 质子或其它阳离子对不饱和键的加成

C Z H C ZH

Z: O,C,S,N

X=CO2

RCOOAgBr2 R+ + Br+

CO +

AgBr

CO2

形成非经典碳正离子: 形成非经典碳正离子:

3) 由其它正离子转化而生成

H+ + H Cl H+ +

NH 2

NaNO 3 HCl

H Ph3CSbF6 SbF 6

2 . 正碳离子的稳定性： 1）电子效应的影响 A CH3 3C > CH3 2CH > CH3CH2 > CH3 σ- p超共轭效应：

B 烯丙型正碳离子：

CH2 CH CH2 CH CH2

p-π共轭

电子离域

CH2

正电荷分散程度大

共轭体系的数目越多，正碳离子越稳定：

CH2 CH 3C

+ + + Ph3C > Ph2CH > PhCH2

CH3 CH2

CH 2 CH 2CH

CH2 CHCH2

CH2

> O 2N

CH2

(CF3)3C+

极不稳定

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此二类正碳离子稳定性极差。

2）. 芳构化效应

3）空间效应

CH3 Cl

+ CH 3

Cl-

(C6H5)3C

H H

(C6H5)3CH +

张力增加，不稳定

稳定性比(C6H5)3C+ 高1011倍

4）溶剂效应：

1) 极性溶剂的诱导极化作用，利于底物的解离。 2) 极性溶剂使正碳离子稳定：

4 碳正离子的反应

与亲核试剂作用---具有电子对的物质结合（Lewis酸碱反应）脱去氢离子生成烯烃重排为更稳定的碳正离子加成反应

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SN 反应 1 与亲核试剂作用

R+ + Y-

R-Y

可能是OH-、卤离子或任何其它阴离子；也可能是带有电子对的中性物种，在后一种情况下，产物是带电荷的。

一 SN1 反应

C Cl

-L-

C+

Nu-

+ Nu

1 烃基结构的影响 2 离去基团的影响 3 溶剂的影响 4 亲核试剂

的影响

（二）

Ｓ反应的立体化学及邻基参与问题Ｎ

OCH3

CH3OH

Neighboring-group participation

I I OH HCl Cl

卤原子参与

※

R C6H5CH(Br)CH3

C6H5CHCH3

27%构型翻转，73%外消旋化

构型保持的取代

Br H H3 C CH3 C C H OH

H C C CH3 OH HBr H H 3C

HBr

Br H H 3C

Br C C

C C

CH3 H Br

H Br H CH3

H3C

C H

NaOH H2O

H CH3 Br + H 3C

H3C

C H

O-

（构型保持）

H H3C

C C

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硫芥和氮芥

CH3 C C H H OH 2 H Br H H3C Br or Br C C H Br ＲＳ２３二溴丁烷，－，－（内消旋结构）

Ｃ－ＨＣ２ＳＣ２Ｈ－ｌｌＣ２Ｈ－－ＨＣ２Ｃ芥子气

CH3

ＲＳＣ２Ｈ－－－ＨＣ２Ｘ一个硫芥

Br H C C H 3C

H CH3 OH2

Br H C C H H 3C CH3 Br or Br

ｌＲＣＳｒｔ－ｉｉｉｇａｅｌｍｔｎＲ－ＨＣ２ＣＳＣ２Ｈ－ｌＨＣＣ２Ｈ２

ＲＲ和ＳＳ２３二溴丁烷，－，－，－

ＨＯ２ｆｓａｔＣｌＲＣ２ＨＯＳＨＣ２Ｈ＋ＨｌＣＲＣ２ＨＯ２ＳＨＣ２Ｈ

硫原子邻位促进作用示例

Cl S HOAc

S Cl HOAc

氮原子邻位促进作用

OAc S + HCl

R R'

N CH2CH2 Cl

R N H2C

R' Cl H2O R CH2

N CH2CH2 OH

CH3

C2H5 C H S S 2 5 HCl H3C C CH2 C C OH H H H2 Cl

H2 H3C CH C SC2H5 Cl

Cl N C2H5 CH2 Cl

N CH C2H5 2

N C2H5

环大小的效应

环的大小对环铵盐形成速率的影响（25℃，水）

Br (CH2)n NH2 (CH2)n + NH2

环的大小对环锍盐形成速率的影响（100℃，20%的二氧六环水溶液）

Cl (CH2)n S C6H5 (CH2 )n + S C6H5

2 3 4 5 6

环原子数

3 4 5 6 7

环生成的相对速率

1 0.014 833 14 0.027

2 3 4 5 1-氯己烷

环原子数

3 4 5 6

环生成的相对速率

1.0000 0.0053 0.2000 0.0170 0.0096

M.I.Page, Chem.Soc.Rev., 2,295(1973)

S.Winstein, J.Am.Chem.Soc.,75,147(1953)

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-OBs对溴苯磺酸基

X OBs

对溴苯磺酸环己基酯的相对反应速率（75 ℃，乙酸）

反应相对速率

X=H X = trans-Cl cis-Cl X = trans-Br cis-Br X = trans-I cis-I 1 4.8

ktrans/kcis

10-4 1.3 10-4

0.10 1.2 1.2 4.3

10-4 103 10-4

800

106

芳基参与

H H H3 C C C CH 3 HOAc OTs

H3C AcO H

H C C H CH3

C H H3C

CH3 OAc

H H3C C

H C CH3 OTs

H H3C

HOAc

H CH3

CH3 H C H H3C C OTs

HOAc H3C

H C C CH3 H

H3C AcO H C C H CH3 H

AcO

C H H3C

CH3 OAc

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C H H3C

CH3 H C OTs

HOAc

芳基的迁移

H H3C AcO C C CH3 H

H H3 C C CH3 H C OAc

H H 3C

CH3 H

S，S-相同化合物

H H C2 H5 C C CH3 OTs

H C2H5

H CH3

C2 H5

H C C H CH3

TsO HOAc

H H H3C C C CH3 OTs

C H H3C O S O

C O

外消旋体

H CH3

H C H C2 H5 C CH3 + OAc C2H5 AcO H C C H CH3

C7H7

Classical Carbocation

涉及非经典碳正离子的邻基参与

(CH3)3C+

C+

CH2

CH2CH2

Nonclassical Carbocation

+ CH5

非经典碳正离子的产生

7 5 1 4 3 2

Cl+

反－7－原冰片烯基对甲苯磺酸酯实验表明：在乙酸中的溶剂解的速度比相应的饱和化合物大 1011倍.产物构型保持.

OTs HOAc

OAc

非经典碳正离子

TsO H H OTs

+ HOTs

TsO

-TsO

AcO

AcOH

Ts = CH3

SO2

溶剂解反应相对速率

2电子3中心体系

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非经典碳正离子中间体: 非经典碳正离子中间体:

H CH3 OH NaBH4

OTs NaOCH3 CH3OH H OCH3

H O PNB = C NO2

OPNB H3C

OPNB H3C H3C

OPNB

k=1.0

104

H Cl

1011

1014

反应相对速率 1.0 （140℃,二氧六环/水）

13.3

148

Br AgOAc HOAc

Br C2H5OH KOAc

OC2H5

SbF6

OAc

芳香环稠合的邻位作用

SbF6

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(H3C)2C Cl (H3C)2C Cl

(H3C) 2C Cl

OBs

BsO

H3C 1.0 (H3C)2C Cl

CH CH3 17.8 (H3C)2C Cl 157

2>3>1

CH3

H3C

CH3

172

37.1

相对溶解速率比较

OTs

TsO

2)σ键参与的非经典正碳离子

D D

D OTs H D HCO2H HCO2 K

O OCH H

exo-

OBs

HOAc

OAc AcO

D D

endo-

H OBs

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7 5 6 H2C 1 2 2 4 3 3 4 6 H2C

7 1

H H

CH C

∗ CH

HOAc

AcO

∗

+ ∗

OAc

O O CH3COH or HOCCH3

H迁移

HOAc C

OAc AcO

+ ∗ OAc

∗ C H H

AcO ∗

再如：

取代基效应对2-降冰片对甲苯磺酯上exo/endo反应速率比值

R R X 181a 16a 3.7a 0.48a 0.37a kexo/kendo

CH3

部分参与

无δ键参与

CH3 Y CH2Br exo(X = OTs, Y = H) endo(X = H, Y = OTs) CO2CH3 F CN X Y exo(X = OTs, Y = H) endo(X = H, Y = OTs) R H CO2CH3 CN

在经典的碳正离子反应中也广泛存在邻基参与，以后各章加以讨论

100b 1.2b 1.1b

返回目录

a：25℃,二氧六环 – 水 b: 乙醇 – 水

亲电加成反应

Br+ H2C C H CH2X H2C Br C H X CH2 Br H2C Br X C H CH2 Br

CH2 C CH2I +Br2 H

H2C Br

C H

CH2 H2C Br

H C Br

CH2

X H2C Br C H CH2 Br H2C

X H C CH2

CH2 C CH2I H

Br+

I H2C Br C H CH2 Br I H2C Br

I C H CH2 Br

Br Br

X=OR,NHR,NH2,NR2,Cl,Br,I

I H2C Br C H CH2 Br H2C Br H C Br

CH2

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CH2 Br

H2C

C CH2OR +Br2 H

H2C Br

C H

H2C Br

H C Br

CH2

H2C C H CH2NHR Br+ H2 C Br C H

HR N CH2 Br NHR CH2 H2C Br

NHR C H CH2 Br

H2C

C CH2OR H

Br+

R O H2C Br CH CH2 Br H2C Br

OR C H CH2 Br

H2 C Br

HR N C CH2 H Br

H2 C

H C

Br Br

R O H2C Br C H CH2 Br H2C Br

OR H C Br CH2

Cl2

H Cl H OOC COO-

OOC

COO-

O H C C O

Cl H COO-

Cl Cl H C C H OOC COO-

H H H H 3C H+

+ +

H CH

3 OH-

H 3C H CH 3

H H 3C OH

H CH3

H HOOC

H COOH

Cl2

H Cl H HOOC COOH

CH3

H3C

C C

Cl H

HOOC Cl

H Cl H C C COOH COOH HOOC Cl

H H 3C OH

H CH3 H H 3C H CH 3 OH

COOH

Br2

O O

二与不饱和化合物的反应

COOH

Br2

COOH

CH3

HO O

(CH3)3C+

CH2

(CH3)3CCH2 C+

CH3

Br O

H C(CH3)3

Ι Br

COOH I O O

(CH 3)3C +

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快

慢

H+

同理

fm =

k PhY 6 % 间位异构体 × × k PhH 2 100 %

kPhH = 6k H

(

所以

k H = k PhH

k f0 = 0 = kH

k PhY ) × (%邻位异构体） 100 k 6 %邻位异构体 2 = PhY × × k PhH k PhH 2 100 6

fp =

k PhY 6 % 对位异构体 × × k PhH 1 100 %

三消去反应

E: H+ -+OR2

Nu: -Hal, -OSO2Ar, -+NR3, -+SR2, -OCOR, -OAr, -OR, -CN -OH (-O+H2)

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Mechanism

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四** 碳正离子的重排反应----Nucleophilic Rearrangement ( Carbon cation rearrangement ) 1 Wagner-Meerwein rearrangement

CH3 CH3 C CH2OH CH3 H+

Cl Cl

CH3 CH3 C CH2OH2 CH3

Cl-

CH3 CH3 C CH2 CH3

CH3 C CH2CH3 CH3

CH3

Cl C CH2CH3 CH3

H2O

CH3C=CHCH3 CH3

反应机理：

Demyahov 重排

HNO2

CH3CH2CH2NH2

+ H2CH2CH3C N N

-N2

+ CH3CH2CH2+ 1,2-亲核重排 CH3CHCH 3

H2O

OH CH3CHCH3

+ CH3CHCH3

Cl-H+

Cl CH 3CHCH 3

CH3CH

CH2

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CH2NH2 HNO2

CH2+

H2O H+ H+

CH2OH 32%

2 Pinacolic Rearrangement

CH3 CH3 CH3 CH3 H+ CH3 C C CH3 CH3 C C CH3 H2O OH +OH2 OH OH

CH3 CH3 C C CH3 OH CH3

H+ 2%

NH2 HNO2 N2

H2O H+

OH 58%

H2O H+

CH3 CH3 C C CH3 +OH CH3

CH3 CH3 C C CH3 O CH3

H2O H+

CH2=CHCH2OH

The stable cation formed superior

OH OH (CH3)2C C Ph Ph OH (CH3)2C C + Ph Ph

（较稳定） 1,2-迁移

OH OH

-H+

Phenyl group move first

H2O

(CH3)2C C Ph Ph

CH3 H3C C C Ph OH Ph +

-H+

PhHC CHPh OH OH

H+

PhHC

CHPh OH

CH3 H3C C C Ph O Ph

（主要产物）

Ph2CH CH +OH

H+

Ph2CH CH O

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Ph H3C C CH2I OH

HgO

H3C C CH2Ph OH+

-H+

CH3 3 CH H3C C C CH3 O

CH 3 3 CH

H+

O (CH3)3C C CH3

CH3 3 CH H3C C C CH3 OH

H3CC CH2Ph O

CH3CH3 H3C C C CH3 OH NH2

CH3CH3

H+

CH3CH3

HNO2

1,2迁移

H3C C C CH3 OH N N +

-N2

H3C C C CH 3 O

H3C C +C CH3 O H

CH3 3 CH H3C C C OH

-H+

CH3CH3 H3C C C+ CH3 OH

OH CH3 CH3

(CH3)3C C CH3

H3C C C CH3

CH3 O CH3

CH3

H3CC C CH3

1 Beckmann Rearrangement

R C N R' OH

C N

O R

C N

R' H

OH mp147

UV light

C N

C6H4OCH3 -p

PCl5

Et2O, -10

Ph H mp171

C N

C6H4OCH3

Ph C N

CH3 OH

PCl5 ethyl ether

O Ph

C N

CH3 H

Ph C N HO

C6H4OCH3

PCl5 Et2O, -10

Ph H

C N

O C6H4OCH3 -p

mp117

mp156

反应机理

OH 2 -H2O R' C=N-R H2O

+ +

O2N

Ph N Br OH PCl5

O2N

NHPh H2O

O2N

COOH Br PhNH2

R' C=N R

H+

R' C=N R

O2N

Ph N OH Br PCl5

O2N

O2N NHCOPh H2O Br

NH2 Br

PhCOOH

R' C=N-R

R'-C R' C=N-R HO

N-R

H2O

-H

O R'-C-NHR

CH3 C N HO

C2H5 C CH2C2H5 H

H2SO4 Et2O

CH3CONH

C2H5 C CH2C2H5 H

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2 Baeyer-Villiger Rearrangement

O CH3 C Ph CF 3CO3H

CH2Cl2

O CH3 C OPh

O CF 3COOH

CH3

OH CH Cl 2 2 C Ph

OH CH3 C Ph CF 3COOH + O

OH CH3 C Ph CF3C O O OH

O CF 3CO3H

CH3COOEt

O O

OH CH3 C OPh +

CF 3COOH

O CH3 C OPh

O * CH3 C CH Ph CH3 PhCO3H CHCl3 O CH3 C OCH Ph CH3

CH3CH=CH2

anhydrous AlCl3

PhCH(CH3)2

O O CF 3CO3H CH3 C OC(CH3)3 CH3 C C(CH3)3 CH2Cl2

PhCH(CH3)2

Na2CO3/H2O 100

O Ph C

O CF 3CO3H PhO C CH2Cl2

CH3 + Ph C OOH H PhOH CH3

CH3COCH3

3 过氧化物的重排------异丙苯氧化重排 + CH3CH=CH2

CH3 CH3 + H+ PhC O OH H3C C O OH2 CH3

AlCl3

CH(CH3)2

O2 自动氧化

1,2-亲核重排反应的立体化学

_H O 2

CH3 H3C C O Ph +

CH3 + H3 C C O Ph

H2O

OH CH(CH3)2

-H+

CH3 H3C C O Ph +OH2

C-O键断裂

( 95 ％光学纯度）

O + (CH3)2C=OH

质子转移

OH + (CH3)2C=O

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Ph H CH2NH2 Et

NaNO2 HClO4,H2O

OH CH2Ph Et

HO Et

CH2Ph

氢迁移键旋转

氢迁移

外消旋体

其他重排反应

H3C C C H H

CH2

H3C C H

C H

CH2

Nu-

Cl C6H5 C H C H CH 2 -Cl C6H5 C H

C H

CH2

Cl-

Nu H3C C H C H CH2

C6H5 C

H C H CH 2Cl

CH3

H+

CH3

A C B C H C+ A B +Nu-NuA C B C H C

B A

H+

1,4迁移

(Z)

(E)

1,2-亲核重排

CH3 CH3

-H+

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HO CH3 + CH3COOH

H2SO4

CH3 OCOCH3

H3+ O OH OH

HO CH3

H2SO4

H2+O CH3

CH3 +

CH3

CH3 +

CH3COOH

CH3

-H+ + OCOCH3 H

OH + Me2CHCHO CH3 H+ H3C O

Ph Ph

RCO3H

Ph Ph

H3C + H OH

H3C

-H+

H3C

+H+ -H2O

O O Ph Ph

O H

O Ph Ph + RCO2H

H+

+ Me2CHCHOH

OH + H3 C

H O +

H3C

OH + H

H3C

-H+

OH+ Ph Ph

Ph + Ph

OH Ph Ph +

CH2OH

1.PhCO3 H 2.HO-/H2O

HO O

CH3

H2SO4

CH3

Br CH3OH CH3CHCH CH2

CH3CH CHCH2OCH3

CH3 + HCl

CH3

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OH H2C CHCH CHCH3 + H2O H2SO4 H3C HC CH CH CH3

H3C CH3 CH3 H2SO4 H2C C CH2CH2CH2 C CH2 H3C

CH3 +

H3C H3C

CH3

CH3CH CH OCH3 + H2O

HCl

CH3CH2CHO +CH3OH

O CH3COCH3

HC C OCH3 + H2O

O NaOH OC2H5

O + HOC2H5

OH CH3

O NaOH

O 2CH3CCH3

H3 C C CH2 CCH3

O NaOH

O HO C CH 2 CH CH3

O NaOH

CCH 2CHCH 3

O OH NaOH

O CH3 O CH3ONa H3C

O CH3 O

H3C

OH H3C C CH CH2 C N

CH3ONa

O CH3CCH2CH2C N

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