cwiwPwZ ‡gv: gvmyg web Inve cÖfvlK, imvqb wefvM XvKv †iwm‡Wbwmqvj g‡Wj K‡jR

cwiwPwZ

‡gv: gvmyg web InvecÖfvlK, imvqb wefvMXvKv †iwm‡Wbwmqvj g‡Wj K‡jR

AvR‡Ki cvV

mgvYyZv

Øv`k †kÖwY

wkLbdj

GB cvV †k‡l wkÿv_©xiv Rvb‡Z cvi‡e-mgvYyZv KxMvVwbK mgvYZv Kx I Zvi kZ© wÎgvwÎK mgvbyZv I Zvi kZ© - Rvb‡Z cvi‡e|

Isomerism/mgvYyZv

‡h mKj †hŠ‡Mi AvbweK ms‡KZ GKB wKš‘ MvVwbK ms‡KZ wfbœ nevi Kvi‡Y Kgc‡ÿ GKwU †fŠZ ev ivmvqwbK a‡g©i cv_©K¨ †`Lvq Zv‡ì †K ci¯ú‡ii Zv‡ì‡K ci¯ú‡ii mgvby e‡j |‡hmKj †hŠ‡Mi AvbweK I MvVwbK ms‡KZ GKB wKš‘ wÎgvwÎK web¨vm wfbœ nevi Kvi‡Y Kgc‡ÿ GKwU †fŠZ ev ivmvqwbK a‡g©i cv_©K¨ †`Lvq Zv‡ì †K ci¯ú‡ii mgvby e‡j |

‡hŠ‡Mi Giæc ag©‡K mgvYyZv(Isomerism) e‡j |

mgvYyZv

StereoisomersStereoisomers// wÎgvwÎK mgvYyZv wÎgvwÎK mgvYyZv

Structural isomerismStructural isomerism/MvVwbK mgvYyZv/MvVwbK mgvYyZv

DiastereomersDiastereomersnot mirror images

EnantiomersEnantiomersNon-superimposable mirror image

MvVwbK mgvYyZv

‡hŠ‡Mi Abyw¯’Z wewfbœ cigvYy ev g~j‡Ki m¤¢ve¨ GKvwaK Ae¯’vb web¨v‡mi cv_©K¨ †nZz‡h mgvYyZvi D™¢e nq Zv‡K MvVwbK mgvYyZv e‡j |

8

1. wkKj mgvYyZv1. wkKj mgvYyZvKve©b wkK‡ji wfbœZv‡nZz G mgvYyZvi D™¢e nq|

9

1. Chain isomerism1. Chain isomerism

C6H14p.2, Q.2

10

2. Ae¯’vb mgvYyZv2. Ae¯’vb mgvYyZv

GKB Kve©b KvVv‡gv Dcw¯’Z wKš‘ Kvh©Kix g~j‡Ki Ae¯’v‡bi wfbœZvi Kvi‡Y G ai‡bi mgvYyZvi D™¢e N‡U|

11

2. Ae¯’vb mgvYyZv2. Ae¯’vb mgvYyZve.g. Butan-1-ol and butan-2-ol

(molecular formula: C4H10O)

12

Wrong !

Q.15

Are they position isomers ?

Giv ci¯ú‡ii wkKj mgvYy

13

3.Kvh©Kix g~jK mgvYyZv3.Kvh©Kix g~jK mgvYyZv

wfbœ wfbœ Kvh©Kix g~j‡Ki &&&&&&&&&&&&&&Dcw¯’wZi Kvi‡Y &&G ai‡bi mgvYyZvi D™¢e nq|

14

Functional Group IsomerismFunctional Group Isomerism

C

H

H

H

C

H

H

O H C O C HH

H

H

H

H

Alcohol EtherVs

C2H6O

New Way Chemistry for Hong Kong A-Level Book 3A1515

Functional Group IsomerismFunctional Group Isomerism

H C

H

H

C

H

H

C

H

O

H C C C H

O H

H

H

H

Aldehyde KetoneVs

C3H6O


4.

‡gUvgvwiRg

4.

‡gUvgvwiRg

Kvh©Kix g~j‡Ki &&&&&&&&&&&Dfq cv‡k Kve©b cigvYyi msLvi wfbœZvi Kvi‡b G ai‡bi mgvYyZvi &&&&D™¢e nq|


4.

‡gUvgvwiRg

4.

‡gUvgvwiRge.g. Methoxypropane and ethoxyethane



4.

‡gUvgvwiRg

4.

‡gUvgvwiRge.g. Pentan-2-one and pentan-3-one


can also be considered as position isomers


OH

OHAe¯’vb mgvYyZv

OH

OHAe¯’vb mgvYyZv

wkKj mgvYyZv

C4H10O


5. U‡UvgvwiRg

5. U‡UvgvwiRg

`ywU wfbœ Kvh©Kix g~j‡Ki g‡a¨ GKwU MwZkxj mvg¨ve¯’v eRvq ZvK‡j G ai‡Yi mgvYyZvi m„wó nq|


5. U‡UvgvwiRg

5. U‡UvgvwiRg

ethenol ethanal

Bbj – wK‡Uv

U‡UvgvwiR

g

C C

H

H

H

OH

C C

H

H

H

H

O


5. U‡UvgvwiRg

5. U‡UvgvwiRg

ethenol ethanal

B‡bvj KvVv‡gv‡Z -OH MÖæcwU mivmwi wØeÜb hy³ Kve©‡bi mv‡_ hy³ _v‡K

C C

H

H

H

OH

C C

H

H

H

H

O


StereoisomerismStereoisomerism

wÎgvwÎK mgvYyZvwÎgvwÎK mgvYyZv


StereoisomerisStereoisomerismm†hŠ‡Mi AvbweK I MvVwbK ms‡KZ GKB wKš‘ wÎgvwÎK web¨vm wfbœ nevi Kvi‡Y G ai‡bi mgvYyZvi m„wó nq|


StereoisomerisStereoisomerismm

wÎgvwÎK mgvYyZv `yB ai‡bi :

1. Geometrical isomerism

2. Optical isomerism


Geometrical IsomerismGeometrical IsomerismC=C double bond.N~Y©b cÖwZeÜKZvB G mgvYyZvi KviY............................

StereoisomerisStereoisomerismm


Rotation about the axis of a double bond through an angle of 90o results in the breaking of the π

bond

maximum overlap of pz orbitals

minimum overlap of pz orbitals


Geometrical Isomerism - CriteriaGeometrical Isomerism - Criteria

d

c

b

a

where a b and c d


wmm- UªvÝ mgvYyZv

C=C double bond Gi mv‡_ hy³ GKB ai‡bi MÖæc ¸‡jv GKB w`‡K _vK‡j Zv‡K wmm/cis mgvYy e‡j|

C=C double bond Gi mv‡_ hy³ GKB ai‡bi MÖæc ¸‡jv wfbœ w`‡K _vK‡j Zv‡K UªvÝ/trans mgvYy e‡j|


Geometrical Isomers Geometrical Isomers

H

Cl

H

Cl

H

H

Cl

Cl

1,2 dichloro 1,2 dichloro

cis-butene-2 trans-butene-2

m.p. 80C 50C

b.p. 60C 48C

1.

Isomers ?

C CBr

CH3

Br

H3CC C

CH3

Br

Br

H3Cand

Cis - same side Trans - across

Cis-trans isomers are also called geometric isomers.There must be two different groups on the sp2 carbon.

C CH3C

H H

HNo cis-trans isomers possible


wKQz geometric isomers mg~‡ni ¸iyZ¡c~Y© chemical properties Gi difference _v‡K1. H COOH

H COOH

H COOH

HOOC H

K1 1.4102 mol dm3 >> 9.3105 mol dm3

K2 8.0107 mol dm3 < 3.6105 mol dm3


O

O

H

OH

O

Formation of intra-molecular hydrogen bond helps to draw electrons from the –OH Weakening O – H

Ease of release of H+

H+

K1 : cis > trans

Geometric Isomers in Cycloalkanes Ring structures like C=C restrict

rotation and therefore can result in cis and trans isomers

34


Optical Isomerism/Av‡jvK mgvYyZv

35


Av‡jvK mgvYyZv

‡h mKj †hŠ‡Mi AvbweK I MvVwbK ms‡KZ GKB wKš‘ wÎgvwÎK web¨vm wfbœ nevi Kvi‡Y GK mgZjxq Av‡jvi cÖwZ wfbœ iæc AvPib K‡i Zv‡ì‡K ci¯ú‡ii Av‡jvK mwµq mgvYy e‡j|

36


Av‡jv mwµq mgvYyZvi kZ©

AcÖwZmg Kve©b cigvYy _vK‡Z n‡e A_©vr KvBivj Kve©b _vK‡Z n‡e |

‡Kvb Sp3 carbon atom Gi mv‡_ PviwU wfbœ wfbœ cigvYy ev MÖæc hy³ _vK‡j H Kve©b cigvYywU AcÖwZmg nq|


KvBivj Kve©b


It is not superimposable with its mirror image

A_©vr cimec‡ii Dci AmgcvwZZ n‡Z n‡e

mirror



plane-polarized light

Light vibrating in ALL possible planes Light vibrating in

only ONE plane


Optically active

Optically active substance can rotate the plane of polarization of plane-polarized light

Measured by a polarimeter.


Optically active

Dextrorotatory(+) : Nwoi KuvUvi w`‡K N~Y©Y (to the right)

Laevorotatory(-): Nwoi KuvUvi wecixZ w`‡K N~Y©Y (to the left)

Dc‡ii bg~bvwU Kx Dextrorotatory ?

No. It is laevorotatory


C

OH

H CH3

C2H5 C

OH

HH3C

C2H5

Enantiomers (對映異構體 )

Giv G‡K Ac‡ii `c©Y cÖwZwe¤^

Giv G‡K Ac‡ii Dci Dc¯’vbxq bq

Giv GK mgZjxq Av‡jvi Zj‡K GKB cwigv‡Y wKš‘ wecixZ w`‡K †Nvivq


g~j¨vqY

UviUvwiK Gwm‡Wi KqwU Av‡jvK mwK&ªq mgvYy m¤¢e?

Maleic acid I Fumaric acidGi g‡a¨ †KvbwUi MjYvsK I ùzUYvsK †ewk

v‡es †Kb?

45


THANKYOU

46

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cwiwPwZ ‡gv: gvmyg web Inve cÖfvlK, imvqb wefvM XvKv †iwm‡Wbwmqvj g‡Wj K‡jR