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Organic chem

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  • 1. 10 Organic Chemistry Semester 1
  • 2. Introduction to Hydrocarbons
    • The study of carbon compounds is called organic chemistry.
    • The study of organic chemistry of biological systems is called biochemistry.
    • Most organic compounds consist of carbon and hydrogen, but may contain other elements such as oxygen, nitrogen or halogens.
    • Hydrocarbons are compounds with only C and H.
  • 3. Organic Chemistry and Hydrocarbons
    • Organic originally meant chemicals that came from organisms
    • Today, organic chemistry is the chemistry of virtually all compounds containing the element carbon
    • Over a million organic compounds, with a dazzling array of properties
  • 4. Introduction to Hydrocarbons
    • Hydrocarbon: a compound composed of only carbon and hydrogen
    H - C C - H H - C - C - H H H H H H C C H H H H y d r o c a r b o n s A l k a n e s A l k e n e s A l k y n e s A r e n e s O n l y c a r b o n - c a r b o n s i n g l e b o n d s O n e o r m o r e c a r b o n - c a r b o n d o u b l e b o n d s O n e o r m o r e c a r b o n - c a r b o n t r i p l e b o n d s O n e o r m o r e b e n z e n e - l i k e r i n g s E t h a n e E t h e n e ( E t h y l e n e ) E t h y n e ( A c e t y l e n e ) B e n z e n e
  • 5. Introduction to Hydrocarbons
    • Carbon has 4 valence electrons, thus forms 4 covalent bonds not only with other elements, but also forms bonds WITH OTHER CARBON ATOMS.
  • 6. Introduction to Hydrocarbons
    • Saturated compounds have only single bonds.
    • Unsaturated compounds have both single and double bonds/triple bonds.
    • Saturated means that no more H atoms can be added to the chain.
  • 7. Introduction to Hydrocarbons
  • 8.
    • Alkanes -
    • What they are
    • Structure
    • Naming
  • 9. What are they?
    • Alkanes : hydrocarbons containing only carbon-carbon single bonds
      • the first two alkanes are methane and ethane
  • 10. Alkanes
    • Physical Properties
      • Gases – liquids – solids
  • 11. Alkanes
    • Many alkanes are used for fuels:
      • methane, propane, butane, octane
    • As the number of carbons increases,
      • so does the boiling and melting pt.
    • The first 4 are gases;
      • Next ten are liquids;
      • higher alkanes are solids
  • 12. Structures of Alkanes
  • 13. Structure
    • Combined with the -ane ending is a prefix for the number of carbons
    • Homologous series-
      • In alkanes, it is: -CH 2 -
      • Alkanes can be straight chain or branched chain structures
  • 14. Structure
    • A straight chain looks like this:
    • Any smaller chain that takes the place of a hydrogen on a parent hydrocarbon is called, a substituent, or the branched part
    CH 3 – CH 2 – CH 2 – CH 2 – CH 3
  • 15. Showing structure
    • You can show structure in three ways:
    • a) the condensed structural formula
    • b) the full structure
    • c) the line-angle formula:
      • a line represents a carbon-carbon bond and an angle represents a carbon atom
      • a line ending in space represents a -CH 3 group
      • hydrogen atoms are not shown in line-angle formulas
    C H 3 C H 2 C H 2 C H 3 C H 3 C H 2 C H 3 C H 3 C H 2 C H 2 C H 2 C H 3 C H 3 C H 2 C H 2 C H 3 C H 3 C H 2 C H 3 C H 3 C H 2 C H 2 C H 2 C H 3 P e n t a n e B u t a n e P r o p a n e P e n t a n e B u t a n e P r o p a n e C o n d e n s e d s t r u c t u r a l f o r m u l a
  • 16. Naming
    • The name of the alkane varies according to the number of C atoms present in the chain.
  • 17. Naming Straight-Chain Alkanes
    • Names recommended by IUPAC (the International Union of Pure and Applied Chemistry)
        • end with -ane, the root part of the name indicates the # of carbons
    • We sometimes still rely on common names,
      • some of which are well-known
      • (ie polyethylene instead of polyethene)
      • (ie Acetic acid instead of ethanoic acid)
  • 18. Branched-Chain Alkanes
    • A hydrocarbon substituent is called an alkyl group .
      • use the same prefixes to indicate the number of carbons,
        • but the -ane ending is now -yl
        • methyl, ethyl, propyl, etc.
    • Gives much more variety to the organic compounds
  • 19. Branched-Chain Alkanes
    • 1. Count the number of Carbons in the main (parent) chain.
    • 2. Number so branches have low #
    • 3. Give position number to branch
    • 4. Prefix more than one branch (di, tri)
    • 5. Use proper punctuation ( - , )
    • longest chain is Heptane
    • side group is methyl
    • Position is #3 carbon
    • name is 3-methyl heptane
    • is an isomer of
    • octane C 8 H 18
  • 20. Branched-Chain Alkanes
    • From the name, draw the structure:
    • 1. Find the parent, with the -ane
    • 2. Number carbons on parent
    • 3. Identify substituent groups; attach
    • 4. Add remaining hydrogens
  • 21. Review of alkanes
    • What elements are present in an alkane
    • What is the prefix that means 4? 6? 1?
    • What types of alkane are there
    • Draw a) line angle, b) condensed structure c) structural formulae for
    • i)propane ii)3methyl octane iii) 2ethyl butane
    • For iii) what is this more correctly named as.
  • 22. Alkenes
    • Multiple bonds can also exist between the carbon atoms
    • Hydrocarbons containing carbon to carbon double bonds are called alkenes C=C C-C=C
    • Called “unsaturated” if they contain double or triple bonds
  • 23. Naming Alkenes
    • Find longest parent that has the double bond in it
    • New ending: -ene
    • Number the chain, so that the double bond gets the lower number
    • Name and number the substituents
  • 24. Alkynes
    • Hydrocarbons containing carbon to carbon triple bonds called alkynes
    • -C C-
    • Alkynes are not plentiful in nature
    • Simplest is ethyne- common name acetylene (fuel for torches)
  • 25. Questions
    • Draw a) line angle, b) condensed structure c) structural formulae for
    • 3 methyl pent-2-ene
    • 1 bromo 3 ethyl hexane
    • Hept-4-yne
    • 2,4 di methyl nonane
  • 26. Cyclic Hydrocarbons (not assessed)
    • The two ends of the carbon chain are attached in a ring in a cyclic hydrocarbon
      • named as “cyclo- ____”
    • hydrocarbon compounds that do NOT contain rings are known as;
      • aliphatic compounds
    • Rings less than 5 are unstable as the bonds are stressed and will tend to easily break.
  • 27. Aromatic Hydrocarbons (not assessed)
    • A special group of unsaturated cyclic hydrocarbons is known as arenes
      • contain single rings, or groups of rings
      • originally called “aromatic hydrocarbons”, because of pleasant odour
      • simplest arene is benzene (C 6 H 6 )
      • Term “aromatic” applies to materials with bonding like that of benzene
  • 28. Aromatic Hydrocarbons
    • Benzene is a six-carbon ring, with alternating double and single bonds
    • Benzene derivatives possible:
      • methylbenzene, 3-phenylhexane, ethylbenzene
      • Other commonly known aromatics are: napthalene, toluene, xylene, phenol.
      • Many aromatics are known carcinogens.
  • 29. General formulae
    • Alkane C n H 2n+2
    • Alkene C n H 2n
    • Alkyne C n H 2n-2
  • 30. Combustion of hydrocarbons
    • Complete combustion (excess air)
    • C n H 2n+2 + O 2 -> CO 2 + H 2 0
    • To balance:
      • Add 1 x O 2 for every C
      • Add ½ O 2 for every H 2
      • Check!
      • Try a few: CH 4 ; C 8 H 18 ; C 4 H 8 ;
  • 31. Summary – carbon chemistry
    • Hydrocarbons
    • Saturated – the alkanes – learn to C 10
    • Structure, naming, branching
    • Unsaturated – alkenes & - kynes
    • Cyclic and aromatic hydrocarbons
    • combustion

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