chapter 5 - home.konkuk.ac.krhome.konkuk.ac.kr/~parkyong/classes/ch05.pdf · professor william tam...

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Created byProfessor William Tam & Dr. Phillis Chang

Chapter 5

StereochemistryChiral Molecules

Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

1. Chirality & Stereochemistry

v An object is achiral (not chiral) if the object and its mirror image are identical


v A chiral object is one that cannot be superposed on its mirror image

Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved. Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

2

2. Isomerisom: ConstitutionalIsomers & Stereoisomers

v Isomers: different compounds that have the same molecular formula● Constitutional isomers: isomers

that have the same molecular formula but different connectivity –their atoms are connected in a different order

2A. Constitutional Isomers


v Examples

andButane 2-Methylpropane

MolecularFormula

ClCl

and1-Chloropropane 2-Chloropropane

ConstitutionalIsomers

C4H10

C3H7Cl


v ExamplesMolecularFormula

and

Butanoic acid Methyl propanoate

OH OCH3

O

O

ConstitutionalIsomers

C2H6O

C4H8O2

OH CH3 O CH3andEthanol Methoxymethane


2B. Stereoisomers

v Stereoisomers are NOT constitutional isomers

v Stereoisomers have their atoms connected in the same sequence but they differ in the arrangement of their atoms in space. The consideration of such spatial aspects of molecular structure is called stereochemistry


3

2C. Enantiomers & Diastereomersv Stereoisomers can be subdivided into

two general categories:enantiomers & diasteromers● Enantiomers – stereoisomers

whose molecules are nonsuperimposable mirror images of each other

● Diastereomers – stereoisomers whose molecules are not mirror images of each other


v Geometrical isomers (cis & trans isomers) are:● Diastereomers

e.g.

(trans)Ph PhPh Ph

(cis)and

Cl

H

Cl

H

H

Cl

Cl

H(trans)(cis)

and


Subdivision of IsomersIsomers

(different compounds with same molecular formula)

Constitutional Isomers(isomers whose atoms

have a different connectivity)

Stereoisomers(isomers that have the same

connectivity but differ in spatial arrangement of their atoms)

Enantiomers(stereoisomers that are

nonsuperimposable mirrorimages of each other)

Diastereomers(stereoisomers that areNOT mirror images of

each other)


3. Enantiomers and Chiral Molecules

v Enantiomers occur only with compounds whose molecules are chiral

v A chiral molecule is one that is NOTsuperimposable on its mirror image

v The relationship between a chiral molecule and its mirror image is one that is enantiomeric. A chiral molecule and its mirror image are said to be enantiomers of each other


4

OH (2-Butanol)

OHH

(I)

HO H

(II)

(I) and (II) arenonsuperimposablemirror images ofeach other


© 2014 Pearson Education, Inc.

Different Conformations

Compounds with different conformations (conformers) cannot be separated.


Different Configurations

Compounds with different configurations can be separated.

Cis–trans isomers have different configurations.

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4. Molecules Having One ChiralityCenter Are Chiral

v A chirality center is a tetrahedral carbon atom that is bonded to four different groups

v A molecule that contains one chirality center is chiral and can exist as a pair of enantiomers


v The presence of a single chirality center in a molecule guarantees that the molecule is chiral and that enantiomeric forms are possible

v An important property of enantiomers with a single chirality center is that interchanging any two groups at the chirality center converts one enantiomer into the other


v Any atom at which an interchange of groups produces a stereoisomer is called a stereogenic center (if the atom is a carbon atom it is usually called a stereogenic carbon)

v If all of the tetrahedral atoms in a molecule have two or more groups attached that are the same, the molecule does not have a chirality center. The molecule is superimposable on its mirror image and is achiral

Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved. © 2014 Pearson Education, Inc.

Asymmetric Center versusStereocenter

Asymmetric (chiral) center: an atom attached to four different groups

Stereocenter: an atom at which the interchange of two groups produces a stereoisomer

6

Me EtClH

(III)

CH

EtMeCl*

mirror

MeEtCl H

(IV)

(III) and (IV) are nonsuperimposablemirror images of each other

sameas


CH

MeMeCl

mirror

sameas

(V) and (VI) are superimposable⇒ not enantiomers ⇒ achiral


4A. Tetrahedral vs. TrigonalStereogenic Centers

v Chirality centers are tetrahedral stereogenic centers

Me EtOHH

*(A)

mirror

MeEtHO H

*(B)

Tetrahedral stereogenic center⇒ chiral

(A) & (B) areenantiomers


(C)H

Ph

Ph

H

mirror(D)

Ph

H

H

Ph

Trigonal stereogenic center⇒ achiral (C) & (D) are identical

v Cis and trans alkene isomers contain trigonal stereogenic centers


7

5. More about the BiologicalImportance of Chirality


(R)-ibuprofen (S)-ibuprofen

Inactive Active analgesic & anti-inflammatory agent

v The activity of drugs containing chirality centers can vary between enantiomers, sometimes with serious or even tragic consequences

v For several years before 1963 thalidomide was used to alleviate the symptoms of morning sickness in pregnant women

Thalidomide


8

v In 1963 it was discovered that thalidomide (sold as a mixture of both enantiomers) was the cause of horrible birth defects in many children born subsequent to the use of the drug

Thalidomide

NNH

O

OO

O

NNH

O

OO

Oenantiomer ofThalidomide

(causes birth defects)(cures morning sickness)


Thalidomide

N

O

O

N

O

O

H

HN

O

O

N

O

O

H

H

(R) -ThalidomideSedative and Hypnotic

(S)-ThalidomideTeratogen

Birth Defects

● One enantiomer is a bronchodilator, the other inhibits platelet aggregation

NH

OMe

OMeOMe

HO

HO

Tretoquinol


v 66% of all drugs in development are chiral, 51% are being studied as a single enantiomer

v Of the $475 billion in world-wide sales of formulated pharmaceutical products in 2008, $205 billion was attributable to single enantiomer drugs


9

Biological MoleculesRULE - Enzymes are chiral reagents because their binding site is chiral

Biological Discrimination

6. How to Test for Chirality:Planes of Symmetry

v A molecule will not be chiral if it possesses a plane of symmetry

v A plane of symmetry (mirror plane) is an imaginary plane that bisects a molecule such that the two halves of the molecule are mirror images of each other

v All molecules with a plane of symmetry in their most symmetric conformation are achiral


Me Me

Cl

H

Me Et

Cl

H

Plane of symmetry

No plane of symmetry

achiral

chiralCopyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

10

Symmetry tests for achiral structures

Any molecule with a plane or center of symmetrymust be achiral.

Plane of symmetry Center of symmetry

7. Naming Enantiomers:The R,S -System

v Using only the IUPAC naming that we have learned so far, these two enantiomers will have the same name:● 2-Butanol

v This is undesirable because each compound must have its own distinct name

OHH

(I)

HO H

(II)

OHRecall:


11

v Rule 1● Assign priorities to the four different

groups on the stereocenter from highest to lowest (priority bases on atomic number, the higher the atomic number, the higher the priority)

7A. How to Assign (R) and (S)Configurations


v Rule 2● When a priority cannot be assigned

on the basis of the atomic number of the atoms that are directly attached to the chirality center, then the next set of atoms in the unassigned groups is examined. This process is continued until a decision can be made.


v Rule 3● Visualize the molecule so that the

lowest priority group is directed away from you, then trace a path from highest to lowest priority. If the path is a clockwise motion, then the configuration at the asymmetric carbon is (R). If the path is a counter-clockwise motion, then the configuration is (S)


12

CH2

CH3C

O HStep 2: CH3

v Example HO H (2-Butanol)

①

③

④

② or ③ ② or ③CC

O HStep 1:

① ④

②

(H, H, H) (C, H, H)


OH

EtMe

①

④

②③

OH

EtMe

H

OH

EtMe EtMe

HO H=

OH

EtMe

H

Arrows are clockwise

(R)-2-ButanolCopyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

13

OCH3

H3C CH2CH3Br

v Other examples①

④

②

③

Cl

H CH3HO

Cl

CH3HO

Counter-clockwise

(S)

①

④

②

③

OCH3

CH2CH3Br

Clockwise

(R)


Cl

H OHBr

Cl

Br HHO

v Other examples

①

④

②

③

Cl

OHBr

Clockwise

(R)

● Rotate C–Cl bond such that H is pointed to the back


OCH3

H IH3C

H

I OCH3H3C

v Other examples

①④

②

③

OCH3

IH3C

● Rotate C–CH3 bond such that H is pointed to the back

Counter-clockwise

(S)Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

14

1

23

4

S-configuration

v Rule 4● For groups containing double or

triple bonds, assign priorities as if both atoms were duplicated or triplicatede.g. C O C

OOC

as

C C CC

CC

as

C C CC

CCC

asC


v Example CH3

H CH=CH2HO①

④ ②

③

(S)

CH3 CH CH2

CH

CCC

HH

CH3

CH CH2

Compare & :

equivalent to

Thus, Þ (H, H, H)

Þ (C, C, H)CH CH2


v Other examplesOH

HCl

CH3

O①

④

②

③

(R)

H2C

HCl

CH3

O

OH

①

④②

③

(S)

C Þ (O, O, C)

C Þ (O, H, H)

②

③


15


Quiz 1 Quiz 2

Quiz 3


Quiz 4

Which one is (S)-enantiomer?

A B

16

8. Properties of Enantiomers:Optical Activity

v Enantiomers● Mirror images that are not

superimposable

mirror

H3CH2C

*CH3

H

ClCH2CH3

*H3C

H

Cl


v Enantiomers have identical physical properties (e.g. melting point, boiling point, refractive index, solubility etc.)

Compound bp (oC) mp (oC)(R)-2-Butanol 99.5(S)-2-Butanol 99.5(+)-(R,R)-Tartaric Acid 168 – 170(–)-(S,S)-Tartaric Acid 168 – 170(+/–)-Tartaric Acid 210 – 212


v Enantiomers● Have the same chemical properties

(except reaction/interactions with chiral substances)

● Show different behavior only when they interact with other chiral substances

● Rotate plane-polarized light in opposite direction


v Optical activity● The property possessed by chiral

substances of rotating the plane of polarization of plane-polarized light


17

v The electric field (like the magnetic field) of light is oscillating in all possible planes

v When this light passes through a polarizer (Polaroid lens), we get plane-polarized light (oscillating in only one plane)

Polaroidlens

8A. Plane-Polarized Light


v A device for measuring the optical activity of a chiral compound

8B. The Polarimeter

a =observed optical rotation


8C. Specific Rotation

D[a] =

25 ac x

temperatureobserved rotation

wavelength of light(e.g. D-line of Na lamp,l=589.6 nm)

concentration of sample solutionin g/mL

length of cellin dm(1 dm = 10 cm)

ℓ

Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved. 68

Calculate [a]Dv A 1.00-g sample is dissolved in 20.0 mL ethanol. 5.00 mL of this

solution is placed in a 20.0-cm polarimeter tube at 25°C. The observed rotation is 1.25° counterclockwise.

Concentration ing/mL.

Length in decimeter

oo

c5.12

0.100.20

0.2000.1

25.1 l

(observed) ][ 25D -=

·÷øö

çèæ

-=

·=aa

18

v The value of a depends on the particular experiment (since there are different concentrations with each run) ● But specific rotation [a] should be

the same regardless of the concentration


v Two enantiomers should have the same value of specific rotation, but the signs are opposite

mirror

HO

*CH2CH3

CH3

H

[a] = + 13.5o25

D

OH

*H3CH2C

CH3

H

[a] = - 13.5o25

D


9. The Origin of Optical Activity


v An equimolar mixture of two enantiomers is called a racemic mixture (or racemateor racemic form)

v A racemic mixture causes no net rotation of plane-polarized light

9A. Racemic Forms

HC2H5

CH3OH

(R)-2-Butanol

HC2H5

H3CHO

(S)-2-Butanol(if present)

rotation

equal & opposite rotation by the enantiomer


19

v A sample of an optically active substance that consists of a single enantiomer is said to be enantiomerically pure or to have an enantiomeric excess of 100%

9B. Racemic Forms and EnantiomericExcess


v An enantiomerically pure sample of (S)-(+)-2-butanol shows a specific rotation of +13.52

D[a] = +13.52

25

v A sample of (S)-(+)-2-butanol that contains less than an equimolar amount of (R)-(–)-2-butanol will show a specific rotation that is less than 13.52 but greater than zero

v Such a sample is said to have an enantiomeric excess less than 100%


v Enantiomeric excess (ee)● Also known as the optical purity

% enantiomericexcess *

observed specific rotationspecific rotation of the

pure enantiomers

= x 100

● Can be calculated from optical rotations


20

v Example● A mixture of the 2-butanol

enantiomers showed a specific rotation of +6.76. The enantiomeric excess of the (S)-(+)-2-butanol is 50%

% enantiomericexcess *

+6.76+13.52= x 100 = 50%


10. The Synthesis of Chiral Molecules

10A. Racemic Forms

O

CH3CH2CCH3 H H ( )-CH3CH2CHCH3+-

OH

+ Ni

Butanone(achiral

molecules)

Hydrogen(achiral

molecules)

( )-2-Butanol(chiral

molecules; but50:50 mixture

(R) & (S))

+-


21

10B. Stereoselective Synthesesv Stereoselective reactions are reactions

that lead to a preferential formation of one stereoisomer over other stereoisomers that could possibly be formed● enantioselective – if a reaction

produces preferentially one enantiomer over its mirror image

● diastereoselective – if a reaction leads preferentially to one diastereomer over others that are possible


+-

OEt

O

FOH

O

F+ EtOH

H+, H2Oheat

racemate ( ) +-racemate ( )

+-

OEt

O

FOH

O

F

+ EtOH

H2Olipase

racemate ( ) (-)(> 69% ee)

OEt

O

F(+)

(> 99% ee)

+


11. Chiral Drugsv Of the $475 billion in world-wide sales of

formulated pharmaceutical products in 2008, $205 billion was attributable to single enantiomer drugs


Singulair(asthma and allergy treatment)

Naproxen(anti-inflammatory drug)

MeO

CH3

CO2H

N

HO CH3

CH3S

NaO2C

Cl


22

Through The Looking-Glass (1872)

v Lewis Carrollv His work may have been affected

by Louis Pasteur

“Maybe Looking-glass milk isn’t good to drink.” Alice



What if Alice had a headache? If she found bottles of acetylsalicylic acid (Aspirin), acetaminophen (Tylenol), naproxen (Aleve), and ibuprofen (Advil, racemic), which pills shouldn’t she take?

12. Molecules with More than OneChirality Center

v In compounds with n tetrahedral stereocenters, the maximum number of stereoisomers is 2n


23

FINDING STEREOCENTERS (CHIRAL CARBONS)

CH3

CH3

HO

H

CH3

CH3

CH3

**

**

*

* *

*

n = 8

28 = 256

12A. How to Draw Stereoisomers forMolecules Having More than OneChirality Center


v Start by drawing the portion of the carbon skeleton that contains the chirality centers in such a way that as many of the chirality centers are placed in the plane of the paper as possible, and as symmetrically as possible


v Next we add the remaining groups that are bonded at the chirality centers in such a way as to maximize the symmetry between the chirality centers


24

v To draw the enantiomer of the first stereoisomer, we simply draw its mirror image


v To draw another stereoisomer, we interchange two groups at any one of the chirality centers• All of the possible stereoisomers for a

compound can be drawn by successively interchanging two groups at each chirality center


v Next we examine the relationship between all of the possible pairings of formulas to determine which are pairs of enantiomers, which are diastereomers


v Structures 1 and 2 are enantiomers; structures 3 and 4 are also enantiomers

v Structures 1 and 3 are stereoisomers and they are not mirror images of each other. They are diastereomers• Diastereomers have different physical

properties - different melting points and boiling points, different solubilities, and so forth


25

v Diastereomers● Stereoisomers that are not

enantiomers

● Unlike enantiomers, diastereomersusually have substantially different chemical and physical properties


C HC H

CH3

ClBr

HOCHCH

CH3

ClBr

OH(I) (II)

C HC H

HO

ClBr

CH3

CHCH

OH

ClBr

CH3(III) (IV)

v (I) & (II) are enantiomers of each otherv (III) & (IV) are enantiomers of each

otherCopyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

C HC H

CH3

ClBr

HOCHCH

CH3

ClBr

OH(I) (II)

C HC H

HO

ClBr

CH3

CHCH

OH

ClBr

CH3(III) (IV)

v Diastereomers of each other:● (I) & (III), (I) & (IV), (II) & (III),

(II) & (IV) Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

12B. Meso Compoundsv Compounds with two stereocenters do

not always have four stereoisomers (22 = 4) since some molecules are achiral (not chiral), even though they contain stereocenters

v For example, 2,3-dichlorobutane has two stereocenters, but only has 3 stereoisomers (not 4)


26

C BrC Br

H

CH3

H

CH3

CBrCBr

H

CH3

H

CH3(I) (II)

C BrC Br

CH3

CH3

H

HCBrCBr

CH3

CH3

H

H(III) (IV)

Note: (III) contains a plane of symmetry, is a meso compound, and is achiral([a] = 0o).


C BrC Br

H

CH3

H

CH3

CBrCBr

H

CH3

H

CH3(I) (II)

C BrC Br

CH3

CH3

H

HCBrCBr

CH3

CH3

H

H(III) (IV)

v (I) & (II) are enantiomers of each other and chiral

v (III) & (IV) are identical and achiralCopyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

C BrC Br

H

CH3

H

CH3

CBrCBr

H

CH3

H

CH3(I) (II)

C BrC Br

CH3

CH3

H

HCBrCBr

CH3

CH3

H

H(III) (IV)

v (I) & (III), (II) & (III) are diastereomersv Only 3 stereoisomers:

● (I) & (II) {enantiomers}, (III) = (IV) {meso}


12C. How to Name Compounds withMore than One Chirality Center

v 2,3-Dibromobutane

● Look through C2–Ha bond

HbBrHa Br

1

2 3

4

C C

Br Ha

12

3

(H, H, H) (Br, C, H)

①④

②③C2: (R) configuration


27


C C

Br Hb

23

4

(H, H, H) (Br, C, H)

● Look through C3–Hb bond

CH3

Ha HbBr

CH3

Br1

23 4

①④

②③

C3: (R) configuration

● Full name:t (2R, 3R)-2,3-Dibromobutane


13. Fischer Projection Formulas13A. How To Draw and Use Fischer

Projections

H3C

Ph

COOH

HOEt Br

Et OH

Br Ph

CH3

COOH

Et OH

Br Ph

CH3

COOH

FischerProjection


Ph

H

COOH

HMe OH

Me H

HO H

Ph

COOH

Me H

HO H

Ph

COOH

FischerProjection

PhCOOH

H Me

OHH


28

H3C

Cl

CH3

HCl H

(I)(2S, 3S)-Dichlorobutane

Cl H

H Cl

CH3

CH3

CH3

Cl

H3C

HClH

(II)(2R, 3R)-Dichlorobutane

H Cl

Cl H

CH3

CH3

enantiomers

v (I) and (II) are both chiral and they are enantiomers of each other


H3C

Cl

CH3

ClH H

(III)(2S, 3R)-Dichlorobutane

H Cl

H Cl

CH3

CH3

v (III) is achiral (a meso compound)v (III) and (I) are diastereomers of each

other

Plane ofsymmetry


14. Stereoisomerism of CyclicCompounds

Me

H Me

H Me

H Me

H

mirror

enantiomers

H

Me Me

H

Plane ofsymmetry

a meso compoundachiral


14A. Cyclohexane Derivatives

Me

Me

Me

Me

v 1,4-DimethylcyclohexanePlane of

symmetry

HMe

MeH

HMe

HMe

cis-1,4-dimethylcyclohexane

trans-1,4-dimethylcyclohexane

• Both cis- & trans-1,4-dimethylcyclo-hexanes are achiral and optically inactive

• The cis & transforms are diastereomers


29

Me Me**


v 1,3-DimethylcyclohexanePlane of

symmetry

(meso)

H

Me

HMe

● cis-1,3-Dimethylcyclohexane has a plane of symmetry and is a meso compound


Me Me**


v 1,3-Dimethylcyclohexane

NO plane of symmetry

enantiomers

H

Me

MeH

H

Me

MeH

● trans-1,3-Dimethylcyclohexane exists as a pair of enantiomers


v 1,3-Dimethylcyclohexane● Has two chirality centers but only

three stereoisomers

(meso)

H

Me

HMe


enantiomers

H

Me

MeH

H

Me

MeH



v 1,2-Dimethylcyclohexane

enantiomers

H

HMe

MeH

HMe

Me

● trans-1,2-Dimethylcyclohexane exists as a pair of enantiomers

mirror


30

v 1,2-Dimethylcyclohexane● With cis-1,2-dimethylcyclohexane

the situation is quite complicated

Me

HMe

HMe

HMe

H

(I) (II)

● (I) and (II) are enantiomers to each other

mirror


v If equilibrium exists between two chiral conformers, molecule is not chiral.

v Judge chirality by looking at the most symmetrical conformer.

v Cyclohexane can be considered to be planar, on average.


Meso Compounds….but the boat conformation does have this plane of symmetry

RULE - as long as one conformation of a compound has a plane of symmetry, the compound will be achiral (meso if there are 2+ asymmetric centers):

In order to see the symmetry with 2,3-dibromobutane, we had to look at the eclipsed (unstable) conformation © 2014 Pearson Education, Inc.

31


15. Relating Configurations throughReactions in Which No Bonds tothe Chirality Center Are Broken

v A reaction is said to proceed with retention of configuration at a chirality center if no bonds to the chirality center are broken. This is true even if the R,S designation for the chirality center changes because the relative priorities of groups around it changes as a result of the reaction


H

O

Me H

HOH

Me H HNaBH4MeOH

Ph Br

NaCNDMSO

Me HPh CN

Me H

Same configuration

Same configurationCopyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

15A. Relative & Absolute Configurationsv Chirality centers in different molecules have

the same relative configuration if they share three groups in common and if these groups with the central carbon can be superimposed in a pyramidal arrangement


32


Reactions of Compounds that Contain an Asymmetric Carbon

The reactant and the product have the same relative configuration because the reaction does not break any of the bonds to the asymmetric carbon.


v The absolute configuration of a chirality center is its (R) or (S) designation, which can only be specified by knowledge of the actual arrangement of groups in space at the chirality center(R)-2-Butanol (S)-2-Butanol

HO H H OH

enantiomersCopyright © 2016 by John Wiley & Sons, Inc. All rights reserved. Copyright © 2016 by John Wiley & Sons, Inc. All rights reserved.

33

16. Separation of Enantiomers:Resolution

e.g.R R'

OH

*(racemic)

Cl OMeO

Ph CF3

(Mosher acidchloride)

R R'

O

OOMe

PhCF3

R R'

O

OOMe

PhCF3+

( 1 : 1 )diastereomers

usually separable either by flash column

chromatography or recrystallization etc.

v Resolution – separation of two enantiomers


v Kinetic Resolution

R2

R1R

OH

*R2

R1R

OH

*R2

R1R

OH

*O

+

(racemic)

● One enantiomer reacts “fast” and another enantiomer reacts “slow”


v e.g.Me3Si

C5H11

OH*

(racemic)

tBuOOH, Ti(OiPr)4

(-)-DET

Me3Si

C5H11

OH

Me3Si

C5H11

OHO+

42%(99%ee)

43%(99%ee)

Me3Si

OHR'

H

Me3Si

OHH

R'

´

S R

ü

* stop reaction at £ 50%* maximum yield = 50%

(-)-DET:COOEt

COOEtHO

HO

(D)-(-)-Diethyl Tartrate


17. Compounds with ChiralityCenters Other than Carbon

R1Si

R2

R4 R3

R1Ge

R2

H R3

R1N

R2

R4 R3X S

R2 R1

O


34


18. Chiral Molecules That Do NotPossess a Chirality Center


35


enantiomers

C CCl

HC

Cl

HCC

Cl

HC

Cl

H

mirror



The only definitive test for chirality is to take the mirror image of the molecule and check if it willsuperimpose :

chiral = mirror image doesnt superimposeachiral = mirror image does superimpose

It doesn’t matter if you recognize any stereocentersor not ! The entire molecule can be chiral !

TESTING FOR CHIRALITY

chapter 5 - home.konkuk.ac.krhome.konkuk.ac.kr/~parkyong/classes/ch05.pdf · professor william tam...

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