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Unit 3 Organic Chemistry

Unit 3 Organic Chemistry. Chemistry 2202. Introduction. Organic Chemistry is the study of the molecular compounds of carbon. eg. CH 4 CH 3 OH CH 3 NH 2 Organic compounds exclude oxides of carbon and ions containing carbon. ie. CO, CO 2 , KCN, CaCO 3

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Unit 3 Organic Chemistry

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  1. Unit 3 Organic Chemistry Chemistry 2202

  2. Introduction • Organic Chemistry is the study of the molecular compounds of carbon. eg. CH4 CH3OH CH3NH2 • Organic compounds exclude oxides of carbon and ions containing carbon. ie. CO, CO2, KCN, CaCO3 are NOT organic compounds!!

  3. History of Organic Chemistry • Organic chemistry can be traced back to ancient times when medicine men extracted chemicals from plants and animals to treat members of their tribes • Organic chemistry was first defined as a branch of modern science in the early 1800's by Jon Jacob Berzelius

  4. Berzelius believed in Vitalism - organic compounds could only originate from living organisms through the action of some vital force • organic compounds originate in living or once-living matter • inorganic compounds come from "mineral" or non-living matter

  5. In 1828, Friedrich Wöhler discovered that urea - an organic compound - could be made by heating ammonium cyanate (an inorganic compound). NH4OCN(aq) (NH2)2CO(s) organic inorganic

  6. organic chemistry branched into disciplines such as polymer chemistry, pharmacology, bioengineering and petro-chemistry • 98% of all known compounds are organic

  7. The huge number of organic compounds is due mainly to the ability of carbon atoms to form stable chains, branched chains, rings, branched rings, multiple rings, and multiple bonds (double and triple bonds) to itself and to many other non-metal atoms.

  8. Sources of Organic Compounds 1. Carbonized Organic Matter - fossil fuels such as coal, oil, and natural gas - basis for the petrochemical industry 2. Living Organisms eg: - penicillin from mold - ASA from the bark of a willow tree

  9. 3. Invention - antibiotics, aspirin, vanilla flavoring, and heart drugs are manufactured from organic starting materials - plastics

  10. Structural Isomers • Structures that have the same molecular formula but different structural formulas are called structural isomers eg. C4H10 Practice: Draw all structural isomers of C5H12 and C6H14

  11. Structural Isomers • structural isomers have the same chemical formula but have different chemical and physical properties.

  12. Hydrocarbons Hydrocarbon Derivatives Classifying Organic Compounds Organic Compounds

  13. hydrocarbons consist of carbon and hydrogen atoms only eg. Methane - CH4 • hydrocarbon derivatives have one or more hydrogen atoms replaced by another nonmetallic atom eg. bromomethane - CH3Br methanol - CH3OH

  14. Aliphatic Hydrocarbons Aromatic Hydrocarbons (benzene based) Hydrocarbons AlkAnes AlkEnes AlkYnes

  15. aliphatic hydrocarbons have carbon atoms bonded in chains or rings with only single, double, or triple bonds • aromatic hydrocarbons contain at least one 6 carbon benzene ring

  16. Aliphatic Hydrocarbons 1. Alkanes • Alkanes are hydrocarbons that have only single bonds between carbon atoms • general formula CnH2n+2 eg. C3H8 C6H14

  17. IUPAC prefixes

  18. Complete this table for the first 10 alkanes

  19. A series of compounds which differ by the same structural unit is called a homologous series eg. each successive member of the alkanes increases by CH2

  20. H – C – C – C – H H H H H H H Representing Alkanes (4 ways) 1. Structural formulas eg. propane

  21. – C – C – C – • Hydrogen atoms may be omitted from structural formulas eg. propane

  22. 2. Condensed Structural Formula eg. propane CH3-CH2-CH3

  23. 3. Line Structural Diagrams eg: propane (the endpoint of each segment is a carbon atom)

  24. 4. Expanded Molecular Formulas eg. propane CH3CH2CH3

  25. Alkyl Groups • An alkyl group has one less hydrogen than an alkane. • General Formula: CnH2n + 1 • To name an alkyl group, use the prefix to indicate the # of carbon atoms followed by the suffix –yl eg. -C7H15 heptyl

  26. Alkyl Groups methyl  -CH3 ethyl  -C2H5  or  -CH2CH3 propyl  -C3H7  or  -CH2CH2CH3

  27. Alkyl Groups • Branched alkanes are alkanes that contain one or more alkyl groups eg.

  28. Naming Branched Alkanes • Find the longest continuous chain of carbons and name it using the alkane name. This is the parent chain. • Number the carbons in the parent chain starting from the end closest to branching. These numbers will indicate the location of alkyl groups.

  29. Naming Branched Alkanes • List the alkyl groups in alphabetical order. Use Latin prefixes if an alkyl group occurs more than once. (di = 2, tri = 3, tetra = 4, etc.) • Use a number to show the location of each alkyl group on the parent.

  30. Naming Branched Alkanes • Use commas to separate numbers, and hyphens to separate numbers and letters. 

  31. Naming Branched Alkanes ethyl eg. 7 6 5 4 3 2 1 methyl 4-ethyl-3-methylheptane

  32. Naming Branched Alkanes Practice: • p. 336 - 339 #’s 5 - 11

  33. Alkenes and Alkynes • saturated compounds contain only single bonds between carbon atoms eg. alkanes • saturated compounds have the maximum number of hydrogen atoms bonded to carbon atoms

  34. Alkenes and Alkynes • unsaturated compounds contain double or triple bonds between carbon atoms eg. alkenes and alkynes

  35. Alkenes and Alkynes • General Formulas: • Alkenes CnH2n • Alkynes CnH2n - 2

  36. Naming Alkenes and Alkynes • Name the longest continuous chain that contains the double/triple bond. Use the smallest possible number to indicate the position of the double or triple bond.

  37. Naming Alkenes and Alkynes • Branches are named using the same rules for alkanes. Number the branches starting at the same end used to number the multiple bond.

  38. Naming Alkenes and Alkynes • p. 347 #’s 17 - 19 • p. 354 #’s 28 & 29

  39. Cyclic Hydrocarbons • Pp. 356 – 358 • questions 30 & 31

  40. 2 1 3 3-ethyl-1-methylcyclopentane cyclopentane ethyl methyl 1-ethyl-3-methylcyclopentane

  41. methyl 1,2,3,4-tetramethylcyclohexane

  42. Aromatic Compounds • Aromatic hydrocarbons contain at least one benzene ring. • The chemical formula for benzene, C6H6 , was determined by Michael Faraday in 1825. • Structural formula was determined by August Kekulé in 1865.

  43. Aromatic Compounds • benzene ring consists of six carbon atoms, each of which is bonded to a hydrogen atom (Try to draw this!!) • C6H6 can be drawn with alternating single and double bonds.

  44. Aromatic Compounds • While C=C double bonds are shorter than C-C single carbon bonds, x-ray crystallography shows that all six C-C bonds in benzene are the same length. • Benzene molecules behave like alkanes in chemical reactions, not like the alkenes

  45. Aromatic Compounds • Kekulé thought benzene could exist in two forms and used the idea of resonance to explain its structure. • The resonance structure is an average of the electron distributions.

  46. or Aromatic Compounds

  47. Aromatic Compounds • bonding electrons that were thought to be in the double bonds are delocalized and shared equally over the 6 carbon atoms • the bonds in benzene are like “1 ½” bonds – somewhere between single and double.

  48. Naming Aromatic Compounds • an alkyl benzene has one or more H atoms replaced by an alkyl group. • name the alkyl groups, using numbers where necessary, followed by the word benzene.

  49. Aromatic Compounds methylbenzene ethylbenzene propylbenzene

  50. Aromatic Compounds 1,3-dimethylbenzene 1,4-dimethylbenzene 1,2-dimethylbenzene

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