Organic Chemistry


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Organic Chemistry

  1. 1. HydrocarbonsThose compounds which contain only carbonand hydrogen.There are two types of hydrocarbons:1- saturated hydrocarbons: in which allcarbon bonds are sigma (σ)bonds,include alkanes and cycloalkanes.
  2. 2. 2- unsaturated hydrocarbons: which contain sigmaas well as pi-bonds, include alkenes (paraffin) andAlkynes (acetylenes).
  3. 3. Nomenclature of organic :compoundsThe IUPAC rules for alkanes3. The general name for acyclic saturated hydrocarbon is Alkanes. The – ane ending is used for all saturated hydrocarbons
  4. 4. 2: alkanes without branches arenamed according to the number ofcarbon atoms.
  5. 5. CH4 MethaneCH3CH3 EthaneCH3CH2CH3 PropaneCH3(CH2)2CH3 n- butaneCH3(CH2)3CH3 n- pentaneCH3(CH2)4CH3 n- hexaneCH3(CH2)5CH3 n- heptaneCH3(CH2)6CH3 n- octaneCH3(CH2)7CH3 n- None
  6. 6. 3: for alkanes with branchedchains, the root nameIs that of the longest continuouschain of carbon atoms, forexample CH3CH CHCH2CH3 CH3CH3
  7. 7. The longest continuous chain(colored C’s) has five carbonatoms .the compound is thereforenamed as substituted pentane.
  8. 8. 4: Groups attached to themain chain are calledsubstituents. Saturatedsubstituens that containonly carbon and hydrogencalled alkyl groups
  9. 9. Alkyl groups- CH3 Methyl- CH2CH3 Ethyl- CH2CH2CH3 n-Propyl CH3CHCH3 isopropyl
  10. 10. Other substituent• -OH • Hydroxy• -NO2 • Nitro• -OCH3 • Methoxy• -CN • Cyano• -Cl • Chloro• -Br • Bromo• -F • Flouro• -I • Iodo• -NH2 • Amino
  11. 11. In the example, each branch has onlyone carbon. derived from thehydrocarbon methane by removingone of the hydrogens, it is called themethyl group.CH3- or Me-
  12. 12. 5: groups are located by a name andnumber.The main chain is numbered in such a waythat the first substituent receive the lowestpossible number.` 1 2 3 4 5 CH3 CH CH CH2 CH3 CH3 CH3
  13. 13. When two identical groups areattach to the main chain, prefixessuch as di, tri, and tetra- are used.The previous compound is correctlynamed as 2,3 - dimethylpentane
  14. 14. 6: Punctuation is important inwriting IUPAC names .Thenames are written as one word.Numbers are separated fromeach other by commas andfrom letters by hyphens.
  15. 15. If two or more different types ofsubstituents are present, they arelisted alphabetically, except thatprefixes such as di- and tri- are notcounted for alphabetizing.
  16. 16. Examples:Give the IUPAC name for the followingcompounds.A: CH3 CH CH2 CH3 CH3 CH3B: CH3 CH2 CH CH3 C: CH3– C-CH3 NO2 CH3
  17. 17. D) CH3C(CH3)3 E) BrCH2CH2CHCl2
  18. 18. CycloalkanesCarbocyclic hydrocarbons that arenamed by placing the prefix cyclo-before the alkane name correspondingto the number of carbon atoms in thering.
  19. 19. Cyclopropane cyclobutane cyclopentaneCyclohexane cyclooctane
  20. 20. When the ring carry alkyl or halogen substituents, they are named in the usual way. CH3 CH3 CH3 CH3 CH3Methylcyclopropane 1,1-dimethylcyclopentane 1,2-dimethylcyclopentane
  21. 21. Alkenesare hydrocarbons that contain onedouble bond, When the molecule containtwo double bonds it is often called a diene
  22. 22. CH2=CH2 Ethene (ethylene)CH2=CH-CH3 PropeneCH2=CH-CH2-CH3 Butene-1CH3-CH=CH-CH3 Butene-2
  23. 23. CH3 CH3cyclopentene 1-methylcyclopentene 3-methylcyclohexene
  24. 24. Preparation of alkenesThe most used methods forpreparations of alkenes andalkynes are based onelimination reactions elimination C C C C Y Z alkene
  25. 25. 1- dehydrogenation This reaction includes removal of hydrogen from saturated hydrocarbons in presence of a catalyst and at high temperature e.gH3C Cr2O 3/Al 2O 3 H3C CH3 + CH3 H2C + H2 CH3
  26. 26. dehalogenation-2The reaction includes removal ofhalogen of 1,2- dihalogenderivatives of alkanes by meansof Zn dust and methanol H3C CHBr Zn CH3OH CH3-CH=CH2 + ZnBr2BrH2C
  27. 27. 3- Dehydration: Dehydration of secondary and tertiaryalcohol using dilute sulphuric acid CH3CH2CHOHCH3 CH3CH=CHCH3 + H2O
  28. 28. 4- DehydrohalogenationBy the action of ethanolic potassiumhydroxide on alkyl halides, eg propene frompropyl bromide KOHCH3CHBrCH3 CH2=CHCH3 KOHCH3CH2CHBrCH3 CH3CH=CHCH3
  29. 29. Chemical properties of alkenesOwing to the presence of the double bondthe alkenes undergo addition reactions C=C + E – Nu C+ CE CNu CE
  30. 30. 1-HydrogenationAlkenes are hydrogenated underpressure of hydrogen at the presenceof a catalyst catalystCH2 = CH2 + H2 CH3 - CH3
  31. 31. 2- HydrationAlkenes are catalytically hydratedin dilute acid solution givingalcohols H+CH3CH =CH2 + H2O CH3CHOHCH3
  32. 32. 3- HalogenationChlorine and bromine are readily addeto the double bond in the darkCH2 = CH2 + Br2 CH2Br – CH2Br
  33. 33. alkynes NomenclaturesAlkynesName Formula Structural FormulaEthyne C2 H 2 CH ≡ CH(Acetylene)Propyne C3 H 4 CH≡ C-CH31-Butyne C4 H 6 CH≡ C-CH2-CH32-Butyne C4 H 6 CH3-C≡ C-CH3
  34. 34. General methods for preparation of alkynes1- By the action of potassium hydroxideon gem or Vicinal dihalidethe reaction proceeds in two steps ethanolBrCH2CH2Br + KOH CH2=CHBr ethanolCH2= CHBr + KOH CH≡CH+2KBr+H2O Acetylene
  35. 35. 2- DehalogenationBy the action of zinc dust and heat ontetrahalogeno alkanesCH3CBr2-CHBr2 + 2 Zn Heat -2ZnBr2 CH3 – C≡ CH
  36. 36. Chemical properties of alkynes :Undergo the same reaction as alkenes butusing two moles of the reagent1- CH3C = CH 2H2/Pd CH3CH2CH3Propyne n- propane 2Cl22- CH = CH + Cl2CH-CHCl2 2HBr3- CH3C = CH CH3CBr2CH3
  37. 37. Aromatic hydrocarbonsAromatic are cyclic, they are unsaturated,usually have three conjugated double bonds foreach ring of carbon atoms , not all aromatic arehydrocarbon e.g pyridine N Pyridine
  38. 38. BenzeneBenzene is the an example for aromatichydrocarbons.Benzene has six pi electrons two from eachof the double bonds benzene
  39. 39. Fused ring systemThose are aromatic similar to benzene with morethan one benzene ring e.g naphthalein andanthracene anthracene naphthalene
  40. 40. Substituted benzeneThe benzene ring minus one hydrogen (C6H5-)is named as phenyl group. In general groupderived from aromatic compounds by removingOne hydrogen from carbon called aryl group.When one hydrogen replaced by other group iscalled monosubstituted
  41. 41. O OH O H Cl CH3chlorobenzene benzoic acid toluene benzaldehyde O NH2 NH2 OCH3 benzamide aniline anisole
  42. 42. Cl CH3 Cl CH31,2-dichlorobenzene o-xylene O OH OH 2-hydroxyben zoic acid
  43. 43. Reactions of Benzene•Benzene is always stable because of its delocalized (π) bonds.•Benzene is therefore chemically less reactivethan unsaturated aliphatic hydrocarbons.
  44. 44. (1) Halogenation: Br F e B r2 Br2 + HBr+
  45. 45. (2) Nitration: NO 2 H 2S O 4+ HNO3 + H2 O
  46. 46. (3) Sulphonation: SO3H+ H 2S O + H2O 4 Benzene sulphonic acid
  47. 47. (4) Alkylation: CH3+ CH3Cl + HCl