有机化学-手性分子
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Chirality
Optical activity* (旋光性)
• Clockwise, (+) or (d) • Counterclockwise, (-) or (l)
[] D t l c specific rotation wavelength (589nm) temperature optical rotation in degress length of sample container (dm) concerntration g/ml
Chiral molecules that do not possess chirality center
(1R,2R)-1,2-dibromo cyclopropane
(1S,2S)-1,2-dibromo cyclopropane
meso-1,2-dibromo cyclopropane
Prepared by Yang R. L. Prepared by Yang R. L.
The S-image of limonene is present in the cones of fir trees and has a turpentinelike odor; the R-mirror image gives oranges their characteristic fragrance
Enantiomers* Image and mirror image are not superimposable
Diastereomers* Not related as image and mirror image
(苏式)
Prepared by Yang R. L. Prepared by Yang R. L.
Molecules with two stereocentres
Morphine
Prepared by Yang R. L. Prepared by Yang R. L.
Molecules with two stereocentres
Meso* forms (内消旋体)
Prepared by Yang R. L.
Fisher projection* COOH COOH H C OH H OH chiral CH3 CH3
carbon
横前 竖后
Prepared by Yang R. L.
Prepared by Yang R. L.
2
Fisher projection*
4
Nomenclature: R, S
4
Thalidomide (沙利度胺)
S
R
Newborn male infant showing typically malformed limbs caused by thalidomide ingested by the mother during early pregnancy
Prepared by Yang R. L.
Question-3
• 含有手性碳的分子是手性分子 • 含有一个手性碳的分子一定是手性分子 • 不能与其镜像重合的分子是手性分子 • 手性分子与其镜像互为对映体
Prepared by Yang R. L.
Prepared by Yang R. L.
Question-1
Indicate whether there is plane of symmetry in the molecules below
Prepared by Yang R. L.
Optical activity* (旋光性)
Rotation
Enantiotropy* (对映)
enantiomer chiral carbon
Plane-polarized light
Sample cell
Analyzer
与镜像不能重合的分子具有旋光性
t= []D
lc
wenku.baidu.com
Prepared by Yang R. L.
Plane polarized light (平面偏振光 )
Beam of light
Enantiotropy* (对映)
Normal light
Polarizer
Plane-polarized light
Prepared by Yang R. L.
Epimers (差向异构体)
Chiral molecules that do not possess chirality center
Ephedrine (麻黄碱)
Pseudoephedrine (伪麻黄碱)
Hexahelicene Top view
Side view
Prepared by Yang R. L.
Prepared by Yang R. L.
6
Isomers
Isomers
＃ Stereochemistry
of electrophilic addition reactions of alkenes
(赤式)
Constitutional isomers Differ in order of attachment Stereoisomers Differ in spatial orientation
Prepared by Yang R. L.
Caution
D, L and R, S has nothing to do with direction of light rotation! Just rules of nomenclature
Propanolol (心得安)
R
S
男性避孕
治心脏病
D-(-)-Lactic acid
The centaur Chiron taught young Askelpios the art of healing
• 3-甲基环己烯
Prepared by Yang R. L.
Prepared by Yang R. L.
Chiral* molecules (手性分子)
True or false
Stereochemistry of electrophilic addition reactions of alkenes
#Separating
enantiomers
Prepared by Yang R. L.
Prepared by Yang R. L.
Stereochemistry of electrophilic addition reactions of alkenes
Prepared by Yang R. L. Prepared by Yang R. L.
Molecules with several stereocentres
• Molecules with n stereocenters can have 2n stereoisomers • Morphine 25 = 32 • Nature makes only 1
S
S R
Prepared by Yang R. L.
R
S
D-葡萄糖
Prepared by Yang R. L.
Nomenclature: D, L
R, S- in Fisher projection
S L-甘油醛 L-丙氨酸
changes into
R
R
Prepared by Yang R. L. Prepared by Yang R. L.
(+) (-) Meso ()
168-170 168-170 146-168 206
+12 -12 0 0
1.7598 1.7598 1.6660 1.7880
139.0 139.0 125.0 20.6
Prepared by Yang R. L.
Prepared by Yang R. L.
Molecules with two stereocentres
Prepared by Yang R. L.
7
Prepared by Yang R. L.
D-(+)-Alamine
Prepared by Yang R. L.
4
Enantiomers in nature
Racemic mixtures (外消旋体)
• Equal quantities of d- and l- enantiomers • Notation: (d,l) or () • No optical activity • The mixture may have different b.p. & m.p. from the enantiomers
3 2
1
3 1
2
S-lactic acid
R-lactic acid
Prepared by Yang R. L.
Prepared by Yang R. L.
Nomenclature: D, L
CHO OH H OH * OH CH2OH
R
Nomenclature: R, S
R
D-甘油醛
H HO H H
changes back into
S
3
R, S- in Fisher projection
Biological discrimination
Prepared by Yang R. L.
Prepared by Yang R. L.
Properties of enantiomers
• Same boiling point, melting point & density • Same refractive index (折射率) • Different direction of rotation in polarimeter • Different interaction with other chiral molecules (enzymes)
Prepared by Yang R. L.
5
Physical properties of tartaric acid
Stereoisomer m.p. (C) []D Density (g/cm3) Solubility at 20C (g/100ml H2O)
Chiral molecules that do not possess chirality center
Prepared by Yang R. L. Prepared by Yang R. L.
1
#Chiral,
cheir & chiron
• 3-氯戊烷 • 3-氯丁烯
Question-2
Point out the chiral carbon in the molecules below
• 2-甲基-3-氯戊烷
Optical activity* (旋光性)
• Clockwise, (+) or (d) • Counterclockwise, (-) or (l)
[] D t l c specific rotation wavelength (589nm) temperature optical rotation in degress length of sample container (dm) concerntration g/ml
Chiral molecules that do not possess chirality center
(1R,2R)-1,2-dibromo cyclopropane
(1S,2S)-1,2-dibromo cyclopropane
meso-1,2-dibromo cyclopropane
Prepared by Yang R. L. Prepared by Yang R. L.
The S-image of limonene is present in the cones of fir trees and has a turpentinelike odor; the R-mirror image gives oranges their characteristic fragrance
Enantiomers* Image and mirror image are not superimposable
Diastereomers* Not related as image and mirror image
(苏式)
Prepared by Yang R. L. Prepared by Yang R. L.
Molecules with two stereocentres
Morphine
Prepared by Yang R. L. Prepared by Yang R. L.
Molecules with two stereocentres
Meso* forms (内消旋体)
Prepared by Yang R. L.
Fisher projection* COOH COOH H C OH H OH chiral CH3 CH3
carbon
横前 竖后
Prepared by Yang R. L.
Prepared by Yang R. L.
2
Fisher projection*
4
Nomenclature: R, S
4
Thalidomide (沙利度胺)
S
R
Newborn male infant showing typically malformed limbs caused by thalidomide ingested by the mother during early pregnancy
Prepared by Yang R. L.
Question-3
• 含有手性碳的分子是手性分子 • 含有一个手性碳的分子一定是手性分子 • 不能与其镜像重合的分子是手性分子 • 手性分子与其镜像互为对映体
Prepared by Yang R. L.
Prepared by Yang R. L.
Question-1
Indicate whether there is plane of symmetry in the molecules below
Prepared by Yang R. L.
Optical activity* (旋光性)
Rotation
Enantiotropy* (对映)
enantiomer chiral carbon
Plane-polarized light
Sample cell
Analyzer
与镜像不能重合的分子具有旋光性
t= []D
lc
wenku.baidu.com
Prepared by Yang R. L.
Plane polarized light (平面偏振光 )
Beam of light
Enantiotropy* (对映)
Normal light
Polarizer
Plane-polarized light
Prepared by Yang R. L.
Epimers (差向异构体)
Chiral molecules that do not possess chirality center
Ephedrine (麻黄碱)
Pseudoephedrine (伪麻黄碱)
Hexahelicene Top view
Side view
Prepared by Yang R. L.
Prepared by Yang R. L.
6
Isomers
Isomers
＃ Stereochemistry
of electrophilic addition reactions of alkenes
(赤式)
Constitutional isomers Differ in order of attachment Stereoisomers Differ in spatial orientation
Prepared by Yang R. L.
Caution
D, L and R, S has nothing to do with direction of light rotation! Just rules of nomenclature
Propanolol (心得安)
R
S
男性避孕
治心脏病
D-(-)-Lactic acid
The centaur Chiron taught young Askelpios the art of healing
• 3-甲基环己烯
Prepared by Yang R. L.
Prepared by Yang R. L.
Chiral* molecules (手性分子)
True or false
Stereochemistry of electrophilic addition reactions of alkenes
#Separating
enantiomers
Prepared by Yang R. L.
Prepared by Yang R. L.
Stereochemistry of electrophilic addition reactions of alkenes
Prepared by Yang R. L. Prepared by Yang R. L.
Molecules with several stereocentres
• Molecules with n stereocenters can have 2n stereoisomers • Morphine 25 = 32 • Nature makes only 1
S
S R
Prepared by Yang R. L.
R
S
D-葡萄糖
Prepared by Yang R. L.
Nomenclature: D, L
R, S- in Fisher projection
S L-甘油醛 L-丙氨酸
changes into
R
R
Prepared by Yang R. L. Prepared by Yang R. L.
(+) (-) Meso ()
168-170 168-170 146-168 206
+12 -12 0 0
1.7598 1.7598 1.6660 1.7880
139.0 139.0 125.0 20.6
Prepared by Yang R. L.
Prepared by Yang R. L.
Molecules with two stereocentres
Prepared by Yang R. L.
7
Prepared by Yang R. L.
D-(+)-Alamine
Prepared by Yang R. L.
4
Enantiomers in nature
Racemic mixtures (外消旋体)
• Equal quantities of d- and l- enantiomers • Notation: (d,l) or () • No optical activity • The mixture may have different b.p. & m.p. from the enantiomers
3 2
1
3 1
2
S-lactic acid
R-lactic acid
Prepared by Yang R. L.
Prepared by Yang R. L.
Nomenclature: D, L
CHO OH H OH * OH CH2OH
R
Nomenclature: R, S
R
D-甘油醛
H HO H H
changes back into
S
3
R, S- in Fisher projection
Biological discrimination
Prepared by Yang R. L.
Prepared by Yang R. L.
Properties of enantiomers
• Same boiling point, melting point & density • Same refractive index (折射率) • Different direction of rotation in polarimeter • Different interaction with other chiral molecules (enzymes)
Prepared by Yang R. L.
5
Physical properties of tartaric acid
Stereoisomer m.p. (C) []D Density (g/cm3) Solubility at 20C (g/100ml H2O)
Chiral molecules that do not possess chirality center
Prepared by Yang R. L. Prepared by Yang R. L.
1
#Chiral,
cheir & chiron
• 3-氯戊烷 • 3-氯丁烯
Question-2
Point out the chiral carbon in the molecules below
• 2-甲基-3-氯戊烷