第三章立體化學(xué)

Chapter

3

Stereochemistry-EnantiomerismconformationaldiastereomersgeometricopticalStereoisomers立體異構(gòu)1Constitutional

isomer構(gòu)造異構(gòu)構(gòu)象異構(gòu)configurational構(gòu)型異構(gòu)幾何異構(gòu)光學(xué)異構(gòu)enantiomers對映異構(gòu)非對映異構(gòu)2Enantiomerisms (對映異構(gòu)現(xiàn)象):3Thalidomide4Limonene

(檸檬油精)5Stereochemistry

LanguageSuperimposable

:

Be

indistinguishable

from

their

mirror

imagesNon-superimposable:

Be

distinguishable

from

their

mirrorimages

such

as

your

left

and

right

hands.Chiral:

has

a

non-superimposable

mirror

image

(Greek

="handedness")Achiral:

has

a

superimposable

mirror

imageEnantiomers:

A

pair

of

molecules

that

are

non-superimposablemirror

images

of

each

otherDiastereomers:

are

stereoisomers

that

are

not

enantiomersOptical

activityRacemate:

is

a

50:50

mixture

of

a

pair

of

enantiomers6一.對映異構(gòu)現(xiàn)象(Enantiomerism):Enantiomerism:

左.右手的關(guān)系--手性對映異構(gòu)體(enantiomers):如兩個(gè)分子具有對映，而不能重疊的關(guān)系,為對映異構(gòu)體。7What

chirality

means?Chirality(手性):有鏡像關(guān)系而不能重疊的性質(zhì)(Greek="handedness")Chiral

objects(手性物質(zhì))Achiral

objects(非手性物質(zhì))8What

chirality

means?SPIRAL

GALAXIES(漩渦星云)M51The

Whirlpool

Nebula9M83Southern

Pinwheel1.Chirality(手性):C不對稱的IClHBrC1893年,England

L.

KelvinIHClBr手性分子(chiral

molecule)不重合CClHCH3CH3HCClCH3CH3非手性分子(achiral

molecule)重合mirror10Chiral and

Achiral

Molecule(手性和非手性分子)Achiral

Molecular

:

superimposable

mirror

image非手性分子與其鏡像可以重疊What

chirality

means?11Chiral

Molecular

:

non-superimposable

mirror

image手性分子與其鏡像不可以重疊What

chirality

means?Chiral and

Achiral

Molecule(手性和非手性分子)12What

chirality

means?有鏡像關(guān)系而不能重疊PHYSICSCHEMISTRYBIOLOGY13What

chirality

means?Stereogenic

Centers

otherthan

Carbon:

Si,

N

and

P14Stereogenic

Centers

(手性中心)Stereogenic

carbon(手性碳原子):碳原子連接4個(gè)不同取代基2.Chiral

Center(手性中心):C*

XY許多含有手性中心的分子是手性的(例外:meso)許多手性分子含有手性中心(例外:聯(lián)苯型,丙二烯型)\手性中心的存在與否不是唯一判斷手性分子的標(biāo)準(zhǔn)15ZWWhat

chirality

means?Stereogenic

Centers

(手性中心)COOHHCH3OHPHCH3C2H5SOCH2PhPhOOCOOHStereogenic

faces(手性面)(CH2)8163.分子手性和對稱因素:17分子本身的對稱性對稱面(s)對稱中心(i)一個(gè)分子如具有對稱面或?qū)ΨQ中心則這個(gè)分子無手性---非手性分子(achiral

molecule)Achiral

molecule:有對稱面、對稱中心或?qū)ΨQ軸Symmetry

factors(對稱因素):What

chirality

means?18Meso:

possess

two

or

morechirality

cenenters,

achiralmolecularWhat

chirality

means?19COOHNO2COOHNO2COOHNO2COOHNO2Enantiomers:

without

chirality

centers\手性中心的存在與否不是唯一判斷手性分子的標(biāo)準(zhǔn)HCH3CH3HCH3HCH3HWhat

chirality

means?204.對映異構(gòu)體(Enantiomers)鏡像關(guān)系不重合e.g. (+)乳酸與(-)乳酸HCH3OHCOOHHOCH3HCOOH光學(xué)異構(gòu)體數(shù)目2n

n:

手性

C*

的數(shù)目e.g. HOOC-CH(OH)-CHCl-CH321光學(xué)異構(gòu)體 對映異構(gòu)體 手

性

分

子A

mixture

consisting

of

equal

parts

of

any

pair

of

enantiomersracemic

mixture

(外消旋體)22Enantiomer

(對映異構(gòu)體)相同的沸點(diǎn)、熔點(diǎn)、密度和溶解度不同的光學(xué)特性(Optical

Activity)與手性分子發(fā)生不同的反應(yīng)23Enantiomer

Physical

Properties二.光學(xué)活性(Optical

Activity):手性分子能改變平面偏振光的振動(dòng)方向,這種性質(zhì)叫光學(xué)活性(旋光性).比旋光度(Specific

Rotation):測定方法---用旋光儀左旋(dextrorotatory)

(-)右旋(levorotatory)

(+)[a]

=

a

/

L·C24L:

dm C:

g/mlEnantiomer

Physical

Properties25Optical

Activity

(光學(xué)活性)對映異構(gòu)體的旋光方向相反，而數(shù)值相同左旋

(levorotatory)

(-)

右旋

(dextrorotatory)(+)一個(gè)光學(xué)物質(zhì)的旋光方向

與其構(gòu)型沒有必然的聯(lián)系，同樣構(gòu)型的兩種物質(zhì)可以

有不同的旋光方向。26四.外消旋體(Racemic

Mixture):等量(+)和(-)的混合物用(–)or(dl)表示通過拆分(Resolution)的方法分離不能用蒸餾,重結(jié)晶的方法e.g.

酸奶中的乳酸HCH3OHCOOHHOCH3HCOOH27CH3HHClClCH3mesoHCH3CH3HClClCH3CH3HHClClracemate五.內(nèi)消旋體(Meso

Compound):分子中有對稱面---非手性分子(achiral

molecule)內(nèi)消旋和外消旋有什么差別？內(nèi)消旋是非手性分子外消旋是具有手性的兩個(gè)對映異構(gòu)體的等量混合物二者都無旋光性，但本質(zhì)不同。28六.構(gòu)型標(biāo)記法:1.D,L標(biāo)記法CHOHOCHOHH

OHCH2OHD-(+)-甘油醛CH2OHL-(-)-甘油醛不夠完善,只用于糖類和氨基酸的構(gòu)型標(biāo)記.292.R,S構(gòu)型標(biāo)記法Cahn-Ingold-Prelog

提出30Rule

1:

原子序數(shù)。Cahn

–

Ingold

-Prelog31Rule

2:與手性碳相連的兩個(gè)原子相同時(shí)-CH2(CH2)2CH3

>-CH2CH3

>-CH3

>-HCahn

–

Ingold

-PrelogRule

3:

Isotopes（同位素）

T>D>H.Rule

4:

雙鍵和三鍵C=OC=COCCOHCHHCCC

CHC

CC

CC

CC

CH32C

CRule

5:

R

構(gòu)型優(yōu)先于S

構(gòu)型，順式

（Z)

優(yōu)先于反式

(E)Expression

of

Enantiomers對映異構(gòu)體的表示法Fischer

Projection：The

rules:中心33橫向---向前縱向---向后Rules:1.

Not

remove

out

of

the

paper---180*n,

the

same

compounds----90*n,

the

enantiomersrotation

180°keeptheoriginalfigure

原化合物CH3HCOOHOHHCH3OHOHCOOHCH3COOHHThe

enantionmer

oftheoriginal對映體3435CH3HCOOHCH3HCOOHOHSOHS2.

將其中一個(gè)取代基位置不變，順或逆轉(zhuǎn)其它三個(gè)基團(tuán)，得到的化合物，原有空間關(guān)系不變。Rules:36FischerSawhorseNewmannCHOOHHHHOCH2OHOHHCHOH

CH2OHHOHHOHOHOHCCH2OH37（1）手當(dāng)模型：CH3HCOOHOHS

構(gòu)型CH3（2）

HCOOHOH

固定，其它基團(tuán)順時(shí)針方向轉(zhuǎn)OHS

構(gòu)型（3）CH3HCOOHOHS

構(gòu)型HCH3

COOHOH實(shí)際是S

構(gòu)型COOHH

CH3OH平面是R

構(gòu)型Determination

of

R,S

Methods3839Difference

of diastereomers

and

meso？內(nèi)消旋是非手性分子;外消旋是具有手性的兩個(gè)對映異構(gòu)體的等量混合物。HCH3CH3HClClCH3CH3HClHClCH3HHClClCH3Meso內(nèi)消旋Racemate外消旋Diastereomers and

Meso40非對映異構(gòu)體和內(nèi)消旋HHCH3

CH3HHCl

ClBr

BrCH3CH3ClHHBrCH3CH3ClHHBrCH3

CH3赤式（erythro):

同側(cè)2-氯-3-溴丁烷蘇式

(threo):

異側(cè)2-氯-3-溴丁烷假手性碳：CH3CH3HHHClClClSRS(2S,3s,4R)-2,3,4-三氯戊烷With

two

chiral

carbons？41C2H5CH3HHOHClCH3C2H5HHOHClCH3C2H5HHOHClCH3C2H5HHOHCl構(gòu)象異構(gòu)體對映異構(gòu)體非對映異構(gòu)體？？Conformation and

Configuration:(構(gòu)象異構(gòu)和構(gòu)型異構(gòu))42434445對映異構(gòu)體的合成和化學(xué)：Formation

of

stereogenic

centers(手性中心的產(chǎn)生)：46非手性化合物外消旋體474849Resolution

of enantiomers(外消旋體的拆分):Rules：

Enantiomers

to

DiastereomersDiastereomers

之間physical

property

的差別Enantiomers

與手性化合物反應(yīng)速度的不同501.

化學(xué)分離法:H+(+)-acidH+(-)-acid(±)-acid

+

(-)-baseRacemic無旋光有旋光(+)-acid-(-)-base’salt(diastereomers)(-)-acid-(-)-base’salt(m.p.,or

s.有差別)常用的生物堿:(-)-番木鱉堿,(-)-奎寧,(-)-馬錢子堿,(+)-辛可寧Resolution

methods51522.

色譜分離法：手性柱拆分外消旋體：利用旋光性化合物對對映體的吸附速度不同進(jìn)行分離。3.生物分離法:Enzyme及細(xì)菌等具有旋光性,作用時(shí)具有較強(qiáng)的選擇性.4.播種結(jié)晶法:53對映異構(gòu)體與手性試劑及非手性試劑的反應(yīng)：1.

不斷裂與手性碳相連的鍵的反應(yīng)：CH2.C2H5HClCH3HClC2H5HC2H5ClCH2ClCl.Cl2(S)-2-氯丁烷(R)-1,2-二氯丁烷手性碳的構(gòu)型不變，但符號可能改變。54例：不斷裂與手性碳相連的鍵的反應(yīng)CH3CH3CH3HHHHHClHClHClClCl.+

ClCH3(S)-2-氯丁烷CH3內(nèi)消旋CH32S,3S-二-氯丁烷Diastereomers55HCH3CH3HHCH3CH3HHHCl2Cl2CH3HHCH3HClCH3HCH3HHClRacemate非手性化合物與非手性試劑反應(yīng)56CH3HHHCl

ClCH3HCH3CH3HCH3HCH3ClClHCH3CH3HClClCl2Cl2Diastereomers手性化合物與非手性試劑反應(yīng)57%

ee (

對映體過量百分率）

= R

%

- S

%% O.P

(光學(xué)純度百分率）= [a

]觀察

/

[

a

]純

·

100%2

斷裂與手性碳相連的鍵的反應(yīng)58Why

chiralityis

important?59Why

chiralityis