Structural isomerism

1. 11
Structural IsomerismStructural Isomerism
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2. 22IsomersIsomers
uStructural Isomers:Structural Isomers: Isomers ,which have
same molecular formula, but different
structural formula are called structural
isomers.
uDifferent Structural formula means
Different bond pattern or
Different arrangement of s bonds or
Different connectivity of atoms.
uThe key to organic chemistry is crystal
clear understanding of different terms
used.

3. 33IsomersIsomers
uExample
u1-chloropropane and 2-chloropropane
has different structural formula.

4. 44IsomersIsomers
uExample
ucis-2-butene and trans-2-butene has
same structural formula.

5. 55IsomersIsomers
uType of Structural Isomers.
1. Chain Isomerism
2. Positional Isomerism
3. Functional Isomerism
4. Metamerism.
5. Tautomerism

6. 66IsomersIsomers
uChain Isomerism: Isomers which have
same functional groups but different
arrangement of carbon skeleton in
principal chain or side chains are chain
isomers.
Note 1. No of atoms same
2.No. of D.U same.
3. Functional groups
Same.
4. Carbon skeleton
different

7. 77IsomersIsomers
Example1.Ethylbenzene and o-Xylene.
2. Butanoicacid and
2-methylpropanoicacid,

8. 88IsomersIsomers
uPositional Isomerism: Isomers which
have same functional groups ,same
arrangement of carbon skeleton but
different position of functional groups
or substituents.
Note 1. No of atoms same
2.No. of D.U same.
3. Functional groups
Same.
4. Carbon skeleton Same
5.Position of F.G, differs

9. 99IsomersIsomers
Example 1. 1-butanol & 2-butanol
2. O-Xylene & m-Xylene.

10. 1010IsomersIsomers
uFunctional Isomers: Isomers which
have different functional group.
Note 1. No of atoms same
2. No. of D.U same.
3. Functional groups
differs

11. 1111IsomersIsomers
Example 1. 1-butanol &
Ethoxyethane
2. Ethanal and Oxirane.

12. 1212IsomersIsomers
uMetamers: Isomers which have
different carbonchain lenth along a
functional group withhetro atom (Ex-
Ethers, Esters, secondary amines,
tertiary amines , Secondary amides etc.
Note 1. No of atoms same
2. No. of D.U same.
3. Functional groups
same.
4. Number of carbon
differs along hetro atoms.

13. 1313IsomersIsomers
Example 1. Methoxypropane &
Ethoxyethane
2. Ethylethanoate and
Methylpropanoate.

14. 1414IsomersIsomers
uTautomers: A type of functional
Isomers which exist in rapid equilibrium
in solution are called functional
isomers.
uTautomers are interconvertable in
solution
uTautomers usually differs in position of
H atom at a carbon.
uInterconversion of tautomers can be
catalysed.
uTautomers can’t be seperated in
solution at normal temperature.
uThe more stable form dominates in
equillibrium.

15. 1515IsomersIsomers
uOnly the stable tautomeric form is
counted while counting isomers.
uType-1 Keto- Enol tautomerism.
uExample Cyclohexanone and
cyclohexenol

16. 1616IsomersIsomers
uType-2 Nitro-Acinitro
uExample nitrocyclohexane and
acinitrocyclohexene

17. 1717IsomersIsomers
uType-3 Imine - En-amine
uExample cyclohex-1-en-1-amine
and cyclohexanimine

18. 1818IsomersIsomers
uType-4 Cyano - isocyano
uExample Cyanicacid and isocyanicacid.

19. 1919IsomersIsomers
uType-4 Cyano - isocyano
uExample Cyanicacid and isocyanicacid.

20. 2020IsomersIsomers
uThere are several types of tautomerism, There are several types of tautomerism,
which will be discussed in details in which will be discussed in details in
carbanion section of reaction carbanion section of reaction
mechanism.mechanism.

21. 2121Exercise-1Exercise-1
uIdentify the relationship between given
pair of compounds.

22. 2222Exercise-1Exercise-1
uAnswer:- Functional isomers.

23. 2323Exercise-2Exercise-2
uIdentify the relationship between given pair of
compounds.

24. 2424Exercise-2Exercise-2
uAnswer- Chain isomerism.

25. 2525Exercise-3Exercise-3
uIdentify the relationship between given
pair of compounds.

26. 2626Exercise-3Exercise-3
uAnswer :- Different compounds
uNumber of carbon as well as functional
group differs.

27. 2727Exercise-4Exercise-4
uIdentify the relationship between given
pair of compounds.

28. 2828Exercise-4Exercise-4
uAnswer :- Metamers.
uNumber of carbon along hetro atom
differs.

29. 2929Exercise-5Exercise-5
uIdentify the relationship between given pair of
compounds.

30. 3030Exercise-5Exercise-5
uAnswer :- Functional isomers
uA has Aldehydes group but B has
ketone.

31. 3131Exercise-6Exercise-6
uIdentify the relationship between given pair of
compounds.

32. 3232Exercise-6Exercise-6
uAnswer :- Positional isomers

33. 3333Exercise-7Exercise-7
uIdentify the relationship between given pair of
compounds.
uA .Hexane-2-ol
uB. Heptane-2-ol

34. 3434Exercise-7Exercise-7
uAnswer :- Homologous compounds.
uCompounds with different carbon but
with same functional groups are called
homologous compounds.

35. 3535Exercise-8Exercise-8
uIdentify the relationship between given
pair of compounds.
uA. Methylcyclopropane
uB. Cyclobutane

36. 3636Exercise-8Exercise-8
uAnswer :- Chain isomers

37. 3737Exercise-9Exercise-9
uIdentify the relationship between given
pair of compounds.
uA. 1-Butene
uB. cyclobutane

38. 3838Exercise-9Exercise-9
uAnswer :- Functional isomers (Some
literature also mention ring chain
isomerism.)

39. 3939Exercise-10Exercise-10
uIdentify the relationship between given pair of
compounds.

40. 4040Exercise-10Exercise-10
uAnswer :- Metamers.

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