Organic Chemistry

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Organic Chemistry

• Topic 10

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Uniqueness of carbon

• Up to 4 bonds with other atoms
• Single, double and triple bonds
• Stable covalent bonds C-C or C-H
• Can form chains and rings
• Octet cannot expand so not as reactive

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Describe the features of an homologous series

• Organic means carbon based compounds
• Alkanes C, H all single bonds
• CnH2n2
• Alcohols have OH group bonded to C
• CnH2n1OH

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Features of an homologous series

• Same functional group
• Same general formula
• Successive members add CH2
• Gradation of physical properties
• Similar chemical properties
• Question 1 and 2

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Longer chains are stickier and have higher
boiling points (bp) Question 3
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Formulas

• ethane
• Empirical CH3
• Molecular C2H6
• Structural full and condensed

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• animation

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• Try ethanoic acid

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• Try glucose empirical formula CH2O Mr 180

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conventions

• R or R used for hydrocarbon part
• ROH
• Benzene ring

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• 4 single bonds is tetrahedral 109.5o not 90o,
  tetrahedral
• 3 bonds no lone pairs form 120o, triangular
  planer
• Sterochemical formula wedge forward of a page,
  dotted line behind

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nomenclature

• Learn names of 1-6 carbons
• Page 370 in your book
• Rule 1 Name the longest chain
• Build pentane and show how it rotates around a
  single bond

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• 2 Use the functional group ending as the suffix
  of the name page 371 in the book
• -ane, -ene, -anol,-anone, -anoic acid

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• Name the side chain
• Methyl, ethyl, propyl
• Build 2-methyl butane
• This is an isomer of pentane
• Use the lowest possible to number the carbon it
  is on
• What is 4-methyl pentane?

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• Use prefixes di-, tri-,tetra- to represent more
  than one side chain in alphabetical order
• 1,2 dichloropropane

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• 1-chloro-2-methylpropane (notice alphabetical
  order)

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• Propan-2-ol

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• But-1-ene

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• If a functional group can only be in one place
  leave off the number
• Like propene

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• Butanoic acid

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• Propanone

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• Name the following a) CH3CH2CH2COOH
• b) CHCl2CH2CH3
• c) CH3CH2COCH3

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• Draw the structural formulas of the following
  molecules a) hexanoic acid
• b) butanal

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• Do questions 4-6
• Handout on nomenclature
• Do questions 1-4 pages 374-5

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• Aromatic groups
• Para dichloro benzene

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Structural isomers

• Same molecular formula, different arrangement of
  atoms
• Different structural formula
• Butane and 2-methylpropane

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• Draw and name all the isomers of pentane
• Start with the straight chain and progressively
  pull off the ends

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• Draw and name all the isomers of C6H14

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Structural isomers in alkenes

• Draw and name the isomers of C4H8

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• Draw and name the straight chain isomers of C6H12

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Classes of compounds

• Primary, secondary, tertiary
• To how many carbons is the carbon attached to the
  functional group attached
• Ethanol
• Propan-2-ol
• 2-methylpropan-2-ol

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Trends in physical properties

• Volatility (how easily evaporated)
• Smaller less sticky
• Branched less sticky
• Animation 1
• Functional polar groups more sticky less volatile
• alkanegthalogenoalkane gtaldehyde gtketone
  gtalcohol gtacid

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Solubility in water

• More polar more soluble
• Alcohol, aldehyde, ketone and acid are all
  soluble

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Which compound has the lowest boiling point?
CH3CH2CH(CH3)CH3 (CH3)4C
CH3CH2CH2CH2CH3 CH3CH2OCH2CH3 Do
questions 8 and 9 Do questions 5-8 page 382 for HW
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102 Alkanes

• CnH2n2
• Saturated
• Hydrocarbons
• Strong bonds low reactivity
• However, they burn easily forming CO2 and H2O
• If not enough O2 they form CO or C (soot)

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• Show the equation for burning octane

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• Halogenation of alkanes page 384 in your book
• UV light and Cl2 yields 2 Cl. Radicals
• Called homolytic fission

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Propagation or chain reaction Show
termination step Do this all with molecular
models
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• Do question set 1 for homework
• Ready for a quiz???

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103 Alkenes

• Unsaturated hydrocarbons
• bond has a weak pi( )bond along with the sigma
  (s)

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Addition reactions

• Ni catalyst and H2
• Used in margarine to make saturated fats with
  higher melting points

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• Reaction with halogens
• Propene with Br2 (test for a bond)

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Hydrogen halides

• Produce halogenoalkanes
• Propene with HCl
• HI weaker bonds more reactive than HBr then HCl

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Reaction with water

• Called hydration
• Alkene to alcohol
• Use conc. H2SO4 as a catalyst and steam
• Ethene to ethanol (industrial use to get alcohol)

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polymerization

• Polyethylene
• Monomer is
• Polymer is

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• Polyvinylchloride (PVC)

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• Teflon (polytetrafluoroethene) what is the
  starting material?
• Do questions 10-12

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104 alcohols

• CnH2n1OH
• Nomenclature handout alcohols
• -OH (hydroxyl group) functional group
• Shorter chains soluble in water

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combustion

• Like alkanes
• Equation for burning of ethanol
• Longer chains give off more energy

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oxidation

• Alcohols with orange K2Cr2O7 reduce it to green
  Cr2O3 (breathalyzer test)
• Primary alcohols oxidize to aldehyde then to
  acids
• Ethanol with K2CrO7
• Distill to get ethanal (apple smell)

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• Reflux to get acid
• Lab activity distillation and refluxing

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• Secondary alcohols make ketones
• Propan-2-ol (reflux)

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• Tertiary alcohols do not readily oxidize
• Do questions 13-14
• Do question set 2 for homework

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105 Halogenoalkanes

• CnH2n1X X halogen
• Used as intermediaries in other reactions
• Polar Cd - Cld- C e- deficient
• Nucleophiles e- rich lone pairs attack the e-
  deficient area
• SN substitution nucleophile reactions

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• Examples of nucleophiles H2O OH- NH3 CN-
• SN2 (bimolecular) primary halogenoalkanes

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• SN1 tertiary halogenoalkanes
• Unimolecular
• Secondary halogenoalkanes can undergo either

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• Go to page 395 and draw the 2 mechanisms showing
  curly arrows
• Animation
• Do questions 15-17

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106 Reaction pathways

• see page 406 in the textbook fill in the reagents
  and conditions needed
• Convert 1-chlorobutane into butanoic acid

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• Do proponal from 1-bromopropane

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• 1,2,3 trichlorpropane from propene

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• Esters
• Formed when organic acids react with alcohols
• Fragrances and flavors
• RCOOR

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• Draw methyl methanoate from methanol and ethanoic
  acid

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• Ester from methanoic acid and propanol
• Name and draw the structure
• Nomenclature handout esters
• Do question 7
• Ester lab

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• Do questions 18-20
• Do questions 1-4,6-9,11 pages 416 and 417 in your
  textbook
• Do the SL questions (1-11) in your study guide on
  page 74
• Homework question set 3
• Quiz 103-6