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Stereochemistry

2. Stereochemistry

3. “Samemolformulabutdifferinphysio-
chemicalpropertiesofcompound”

5. “differentialarrangementofatomwithin
molecule,withoutreferencetospace”

6. Metamerism
UnequaldistributionofC-atomsoneitherside
offunctionalgroup
Examples

7. Tatomerism
Isomersareindynamicequilibrium
Example:acetone

8. “thebranchofchemistryconcerned
with the three-dimensional
arrangementofatomsand
moleculesandtheeffectofthison
chemicalreactions”
1.Conformationalisomersdifferonly
byrotationaroundsinglebonds.
2.Configurationalisomersrequire
breakingandreformingbondsto
interconvert.

9. Geometric(cis/trans)isomers
“restrictioninrotationaboutdoublebondor
singlebondincycliccompounds”
Example:alkene;1,2-dimethylcyclopropane

11. Example: cis-3-Hexene and trans-3-Hexene

12. Rulesgoverninggeometric
isomerism
•mustcontainC=Cwithsp
2
hybridization.
•mustcontainbulkygroups
oneachdoublebonded
carbon.

13. •Conversionofcis/transortrans/cisisomers
•compoundheattohightemp.orabsorblight.

14. Geometric(cis/trans)isomerismincycliccompounds
•shownorotationaboutC-Cincycliccompounds
•atleasttwoothergroupsbesidehydrogenonthering
•bulkygroupsmustbeondifferentringcarbonatom

15. Geometric(cis/trans)isomerismincycliccompounds

16. Opticalisomerism
“they have same molecular formula but differin
the way of their arrangement in space”

17. Opticalactivity
“the ability to rotate plain polarized lighteither
to left or right”

18. Polarizedlight
“lightthathasbeenpassthroughapolarizingprism
(nicolprism).Asaresultlightvibratesinoneplane,

19. Polarizedlight
•Thepolarimetermeasurestherotationofplane
polarized-light,thathaspassedthroughasolution.
•Rotation,indegreeis,[α]
•Rightrotation=Clockwise[+]=dextrorotatory(d)
•Leftrotation=Anticlockwise[-]=levorotatory(l)

20. Opticalisomerism
“Aplanewhichdividesanobjectintotwosymmetrical
halvesiscalledplaneofsymmetry;thatobjectissaidbe
Achiral(symmetric)”
AnobjectlackingplaeofsymmettryiscalledChiral
(dissymmetric)orasymmetric.

21. Opticalisomerism
•non-superimposiblemirrorimagesarecalled
enantiomers.
•isomersthatarenotmirrorimagesarecalled
diastereomers.
•the bondedto
iscalledasymmetriccarbonatom.

22. Opticalisomerism

23. Opticalisomerism
Example:Lacticacid

24. Opticalisomerism
•Opticallyactivemoleculecannotbesuperimposed
onitsmirrorimage,alsocalledChiralmolecule.
•Recemisationistheconversionofopticallyacttive
compoundintoarecemicmixture.

25. Opticalisomerism
•Recemicmixtureismixtureofequalpartsof
enantiomers(50d:50l).Thistypeofmixtureis
opticallyinactive.

26. Opticalisomerism
•Mesocompoundshas
,andsuperimposibleonitsmirrorimage.
Opticallyinactive

27. Opticalisomerism
•Resolutionofrecemicmixtureisthesaperationof
enantiomers(dandlisomers)intoanopticallyactive
components(+and-).
•Recemicmixturecanberesolvedbytwomethods:
1.Chemical
2.Bio-chemical

28. Opticalisomerism
•Resolutionofrecemicmixture
1.Chemicalresolution
Recemicmixtureismadetocombinewithanother
opticallyactivecompound,differencesaresetup,
whichexploitsaperation.
Arecemicmixtureofopticallyactivebasecanbe
saperatedbytheuseofanopticallyactiveacid.

29. Opticalisomerism
•Resolutionofrecemicmixture
1.Chemicalresolutionexample:

30. Opticalisomerism
•Resolutionofrecemicmixture
2.Biochemicalresolution
Whencertainbacteriaormouldsareaddedtoa
solutionofarecemicmixturetheybringabout
decompositionofopticallyactiveformmorerapidly
thanothers.

31. Opticalisomerism
•Resolutionofrecemicmixture
2.Biochemicalresolutionexample:racemictartaric
acidcanberesolvedwiththeaidofcertainpenicillin
moldsthatconsumethedextrorotatoryenantiomer
fasterthanthelevorotatoryenantiomer;pure(-)-
tartaricacidcanberecoveredfromthemixture:

32. •TextbookofOrganicChemistrybyBSBhal
andArunBhal