Structural isomerism

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Structural isomerism

  1. 1. Structural Isomerism Exclusively Developed by K. Chandana For my sincere online students. For further enquiry write to chandanakota1@gmail.com
  2. 2. Isomers <ul><li>Structural Isomers: Isomers ,which have same molecular formula, but different structural formula are called structural isomers. </li></ul><ul><li>Different Structural formula means </li></ul><ul><ul><li>Different bond pattern or </li></ul></ul><ul><ul><li>Different arrangement of  bonds or </li></ul></ul><ul><ul><li>Different connectivity of atoms. </li></ul></ul><ul><li>The key to organic chemistry is crystal clear understanding of different terms used. </li></ul>
  3. 3. Isomers <ul><li>Example </li></ul><ul><li>1-chloropropane and 2-chloropropane has different structural formula. </li></ul>
  4. 4. Isomers <ul><li>Example </li></ul><ul><li>cis -2-butene and trans -2-butene has same structural formula. </li></ul>
  5. 5. Isomers <ul><li>Type of Structural Isomers. </li></ul><ul><ul><li>1. Chain Isomerism </li></ul></ul><ul><ul><li>2. Positional Isomerism </li></ul></ul><ul><ul><li>3. Functional Isomerism </li></ul></ul><ul><ul><li>4. Metamerism. </li></ul></ul><ul><ul><li>5. Tautomerism </li></ul></ul>
  6. 6. Isomers <ul><li>Chain Isomerism: Isomers which have same functional groups but different arrangement of carbon skeleton in principal chain or side chains are chain isomers. </li></ul><ul><li>Note 1. No of atoms same </li></ul><ul><ul><ul><ul><li>2.No. of D.U same. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>3. Functional groups Same. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>4. Carbon skeleton different </li></ul></ul></ul></ul>
  7. 7. Isomers <ul><li>Example1.Ethylbenzene and o-Xylene. </li></ul><ul><ul><ul><ul><ul><li>2. Butanoicacid and 2-methylpropanoicacid, </li></ul></ul></ul></ul></ul>
  8. 8. Isomers <ul><li>Positional Isomerism: Isomers which have same functional groups ,same arrangement of carbon skeleton but different position of functional groups or substituents. </li></ul><ul><li>Note 1. No of atoms same </li></ul><ul><ul><ul><ul><li>2.No. of D.U same. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>3. Functional groups Same. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>4. Carbon skeleton Same </li></ul></ul></ul></ul><ul><ul><ul><ul><li>5.Position of F.G, differs </li></ul></ul></ul></ul>
  9. 9. Isomers <ul><li>Example 1. 1-butanol & 2-butanol </li></ul><ul><ul><ul><ul><ul><li>2. O-Xylene & m-Xylene. </li></ul></ul></ul></ul></ul>
  10. 10. Isomers <ul><li>Functional Isomers: Isomers which have different functional group. </li></ul><ul><li>Note 1. No of atoms same </li></ul><ul><ul><ul><ul><li>2. No. of D.U same. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>3. Functional groups differs </li></ul></ul></ul></ul>
  11. 11. Isomers <ul><li>Example 1. 1-butanol & Ethoxyethane </li></ul><ul><ul><ul><ul><ul><li>2. Ethanal and Oxirane. </li></ul></ul></ul></ul></ul>
  12. 12. Isomers <ul><li>Metamers: Isomers which have different carbonchain lenth along a functional group withhetro atom (Ex- Ethers, Esters, secondary amines, tertiary amines , Secondary amides etc. </li></ul><ul><li>Note 1. No of atoms same </li></ul><ul><ul><ul><ul><li>2. No. of D.U same. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>3. Functional groups same. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>4. Number of carbon differs along hetro atoms. </li></ul></ul></ul></ul>
  13. 13. Isomers <ul><li>Example 1. Methoxypropane & Ethoxyethane </li></ul><ul><ul><ul><ul><ul><li>2. Ethylethanoate and Methylpropanoate. </li></ul></ul></ul></ul></ul>
  14. 14. Isomers <ul><li>Tautomers: A type of functional Isomers which exist in rapid equilibrium in solution are called functional isomers. </li></ul><ul><li>Tautomers are interconvertable in solution </li></ul><ul><li>Tautomers usually differs in position of H atom at  carbon. </li></ul><ul><li>Interconversion of tautomers can be catalysed. </li></ul><ul><li>Tautomers can’t be seperated in solution at normal temperature. </li></ul><ul><li>The more stable form dominates in equillibrium. </li></ul>
  15. 15. Isomers <ul><li>Only the stable tautomeric form is counted while counting isomers. </li></ul><ul><li>Type-1 Keto- Enol tautomerism. </li></ul><ul><li>Example Cyclohexanone and cyclohexenol </li></ul>
  16. 16. Isomers <ul><li>Type-2 Nitro-Acinitro </li></ul><ul><li>Example nitrocyclohexane and acinitrocyclohexene </li></ul>
  17. 17. Isomers <ul><li>Type-3 Imine - En-amine </li></ul><ul><li>Example cyclohex-1-en-1-amine </li></ul><ul><ul><ul><ul><ul><li>and cyclohexanimine </li></ul></ul></ul></ul></ul>
  18. 18. Isomers <ul><li>Type-4 Cyano - isocyano </li></ul><ul><li>Example Cyanicacid and isocyanicacid. </li></ul>
  19. 19. Isomers <ul><li>Type-4 Cyano - isocyano </li></ul><ul><li>Example Cyanicacid and isocyanicacid. </li></ul>
  20. 20. Isomers <ul><li>There are several types of tautomerism, which will be discussed in details in carbanion section of reaction mechanism. </li></ul>
  21. 21. Exercise-1 <ul><li>Identify the relationship between given pair of compounds. </li></ul>
  22. 22. Exercise-1 <ul><li>Answer:- Functional isomers. </li></ul>
  23. 23. Exercise-2 <ul><li>Identify the relationship between given pair of compounds. </li></ul>
  24. 24. Exercise-2 <ul><li>Answer- Chain isomerism. </li></ul>
  25. 25. Exercise-3 <ul><li>Identify the relationship between given pair of compounds. </li></ul>
  26. 26. Exercise-3 <ul><li>Answer :- Different compounds </li></ul><ul><li>Number of carbon as well as functional group differs. </li></ul>
  27. 27. Exercise-4 <ul><li>Identify the relationship between given pair of compounds. </li></ul>
  28. 28. Exercise-4 <ul><li>Answer :- Metamers. </li></ul><ul><li>Number of carbon along hetro atom differs. </li></ul>
  29. 29. Exercise-5 <ul><li>Identify the relationship between given pair of compounds. </li></ul>
  30. 30. Exercise-5 <ul><li>Answer :- Functional isomers </li></ul><ul><li>A has Aldehydes group but B has ketone. </li></ul>
  31. 31. Exercise-6 <ul><li>Identify the relationship between given pair of compounds. </li></ul>
  32. 32. Exercise-6 <ul><li>Answer :- Positional isomers </li></ul>
  33. 33. Exercise-7 <ul><li>Identify the relationship between given pair of compounds. </li></ul><ul><li>A .Hexane-2-ol </li></ul><ul><li>B. Heptane-2-ol </li></ul>
  34. 34. Exercise-7 <ul><li>Answer :- Homologous compounds. </li></ul><ul><li>Compounds with different carbon but with same functional groups are called homologous compounds. </li></ul>
  35. 35. Exercise-8 <ul><li>Identify the relationship between given pair of compounds. </li></ul><ul><li>A. Methylcyclopropane </li></ul><ul><li>B. Cyclobutane </li></ul>
  36. 36. Exercise-8 <ul><li>Answer :- Chain isomers </li></ul>
  37. 37. Exercise-9 <ul><li>Identify the relationship between given pair of compounds. </li></ul><ul><li>A. 1-Butene </li></ul><ul><li>B. cyclobutane </li></ul>
  38. 38. Exercise-9 <ul><li>Answer :- Functional isomers (Some literature also mention ring chain isomerism.) </li></ul>
  39. 39. Exercise-10 <ul><li>Identify the relationship between given pair of compounds. </li></ul>
  40. 40. Exercise-10 <ul><li>Answer :- Metamers. </li></ul>
  41. 41. Concept Developed by <ul><li>K.Chandana. </li></ul><ul><li>[email_address] </li></ul>
  42. 42. Concept Developed by <ul><li>Previous Presentation </li></ul><ul><li>DU and isomerism </li></ul><ul><li>Next Presentation. </li></ul><ul><li>How to find no of structural isomers </li></ul>

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