Tang 01 organic chemistry and alkanes

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Tang 01 organic chemistry and alkanes

  1. 1. ORGANIC CHEMISTRY
  2. 2. ORGANIC CHEMISTRY-Organic moleculescontain only C, H, O, Nand sometimes S and P-56 204 570 organicsubstances have beenrecorded
  3. 3. ORGANIC CHEMISTRYWhat allows for the diversity of organic compounds? -Carbon can make 4 bonds -The 4 bonds can be a combination of single, double, and triple bonds methane, CH4 methanal, CH2O ethanenitrile, CH3CN
  4. 4. ORGANIC CHEMISTRYHydrocarbons:When an organic molecule is composed only of hydrogen andcarbon, it is called a hydrocarbon:Alkanes: Hydrocarbons with single bondsAlkenes: Hydrocarbons with double bond(s)Alkynes: Hydrocarbons with triple bond(s)
  5. 5. ALKANES
  6. 6. ALKANES-Characterized by C-C single bonds-Also known as saturated hydrocarbons-empirical formula = CnH2n+2  CnH2n+2, n=8 = C8H18
  7. 7. ALKANESProperties:-Hydrophobic (does not mix with water and other polarsubstances)-Generally low boiling points (due to weak London DispersionForces)- Longer alkane molecules have higher boiling points
  8. 8. ALKANESSome IUPAC* names of alkanes: ethane propane butane All alkanes have the suffix “ane” *International Union of Pure and Applied Chemistry
  9. 9. ALKANESIUPAC naming system:Each alkane also has a prefix based on the number ofcarbon atoms: meth = 1 eth = 2 prop = 3 but = 4 pent = 5 hex = 6 hept = 7 oct = 8 non = 9 dec = 10 undec = 11 dodec = 12
  10. 10. ALKANESIUPAC naming system: Molecular formula Condensed Structural Formula Name CH4 CH4 methane C2H6 CH3CH3 ethane C3H8 CH3CH2CH3 propane C4H10 CH3CH2CH2CH3 butane C5H12 CH3CH2CH2CH2CH3 pentane C6H14 CH3CH2CH2CH2CH2CH3 hexane C7H16 CH3CH2CH2CH2CH2CH2CH3 heptane C8H18 CH3CH2CH2CH2CH2CH2CH2CH3 octane C9H20 CH3CH2CH2CH2CH2CH2CH2CH2CH3 nonane C10H22 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 decane
  11. 11. ALKANESIUPAC naming system: prefix suffix family Number of carbons in the longest chain Ex: methane
  12. 12. ALKANESIUPAC naming system:Name the following alkanes: hexane nonane
  13. 13. ALKANESIUPAC naming system:Not all alkanes are straight chains. Some alkaneshave alkyl side groups (alkyl substituents) attached. -CH3 methyl Ex: -C2H5 ethyl methyl group -C3H7 propyl -C4H9 butyl -C5H11 pentyl -C6H13 hexyl -C7H15 heptyl -C8H17 octyl name: methylbutane
  14. 14. ALKANESIUPAC naming system:For alkanes with side groups… Substituent(s) prefix suffix family Side groups Number of carbons in the longest chain Ex: methylbutane
  15. 15. ALKANESIUPAC naming system:Name the following branched alkanes 1 2 3 4 5 1 2 3 4 5 2-methylpentane 3-methylpentane When there is ambiguity, the substituent must be numbered according to the carbon atom that it is attached to (aim to get the lowest possible number)
  16. 16. ALKANESIUPAC naming system:Which name is incorrect? 1 2 3 4 5 5 4 3 2 1 2-methylpentane 4-methylpentane Aim for the lowest possible number when counting
  17. 17. ALKANESIUPAC naming system:Name the following branched alkanes 1 2 3 4 5 1 2 3 4 5 6 2,3-dimethylhexane 3-ethylpentane
  18. 18. ALKANES IUPAC naming system: Name the following branched alkane 4 51. Find the longest continuous chain CH3 - CH - CH3 of C atoms 1 2 3| (parent chain) CH3 - CH - CH22. Identify any | substitutents CH3 2,4 -dimethylpentane
  19. 19. ALKANESIUPAC naming system: Name the following branched alkane 3 4 5 6 2 7The order ofsubstituents in the 1 8name is based onalphabetical order 9 4,5,5-triethyl-3,6,6-trimethylnonane
  20. 20. ALKANESDrawing alkanes:3 types of diagrams Structural diagram Condensed diagram CH3CH2CH2CH2CH2CH3 Line diagram
  21. 21. ALKANESDrawing alkanes:Line diagrams: 2 4 6 1 3 5 Every end or point on a line diagram represents a carbon atom. Hydrogen atoms are not shown.
  22. 22. ALKANESDrawing alkanes:Draw the following alkanes using line diagrams methylbutane 3-ethyl-3,4-dimethylheptane 2 4 2 4 6 1 3 1 3 5 7
  23. 23. ALKANESWhen two possible names exist: 3-ethyl-5-methylheptane or 5-ethyl-3-methylheptane? The ethyl has priority (and gets the lower number) because it comes before methyl in the alphabet.
  24. 24. ALKANESHomework:Page 175) a, d, f6) a, b7) a, b9) c
  25. 25. CYCLOALKANES
  26. 26. CYCLOALKANES-Ring-like structures of alkanes-empirical formula = CnH2n  CnH2n, n=6 = C6H12
  27. 27. CYCLOALKANESIUPAC naming system:Name the following alkanes:cyclobutane cyclooctane cyclopentane The prefix “cyclo” is added to the alkane name
  28. 28. CYCLOALKANESIUPAC naming system: Name the following alkanes: CH3CH2CH2 2 3 CH2 CH 1 4 6 5 CH2 CH2 4-ethyl-1,1,2-trimethylcyclohexanemethylcyclohexane propylcyclobutane
  29. 29. CYCLOALKANESIUPAC naming system:Draw the following alkanes using line structures:1,1-dipropylcyclopropane 1-ethyl-1,2,5-trimethylcyclopentane
  30. 30. CYCLOALKANESIUPAC naming system:Which name is correct? 1-ethyl-1,2,5-trimethylcyclopentane vs. 2-ethyl-1,2,3-trimethylcyclopentaneWhen two different substituents (ex. ethyl and methyl) can beassigned the same number, then the group that comes first inthe alphabet gets the lowest number.
  31. 31. HALOALKANES
  32. 32. HALOALKANES-Alkanes with halogen atoms-Also known as alkyl halides
  33. 33. HALOALKANESIUPAC naming system:Halogen groups: -F fluoro -Cl chloro -Br bromo -I iodo Just like alkyl substituents, the halogens are placed at the beginning of the name, and are ordered alphabetically.
  34. 34. HALOALKANES IUPAC naming system: Name the following haloalkanes:1,2-dibromo-1-chlorobutane 2-bromo-2-methylpropane 2-bromo-2-chloro-1,1,1-trifluoroethane
  35. 35. STRUCTURAL ISOMERS
  36. 36. STRUCTURAL ISOMERSCompounds with the same molecular formulabut with different bonding arrangements arestructural isomers. Butane isomers Pentane isomers
  37. 37. STRUCTURAL ISOMERSEx: Structural isomers of hexane + boiling points Changing the structure affects the boiling pointThis structure can easily stack and form more London Dispersion Forceswith neighbouring hexane molecules
  38. 38. STRUCTURAL ISOMERSDraw all of the structural isomers of heptane usingline structures:
  39. 39. STRUCTURAL ISOMERSThe longer the chain, the greater the number ofstructural isomers Number of Carbon Atoms Number of Isomers 4 2 5 3 6 5 7 9 8 18 9 35 10 75 12 355 15 4347

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