ORGANIC CHEMISTRY

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ORGANIC CHEMISTRY
HYDROCARBON COMPOUNDS FUNCTIONAL GROUPS
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Alkanes (Saturated Hydrocarbons)

• Hydrocarbons with only single bonds
• (The carbons are saturated with hydrogens)
• Prefixes 1- meth 6 - hex 2 - eth 7 -
  hept 3 - prop 8 - oct 4 - but 9 -
  non 5 - pent 10 - dec
• General Formula - CnH2n2

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Straight-Chain Alkanes

• IUPAC - International Union of Pure and Applied
  Chemistry nomenclature (rules)
• Straight chains (un-branched chains)
• Use a prefix for number of carbons in backbone
• Ending tells the type of hydrocarbon
• Alkanes end in -ane
• Propane, Butane, Heptane

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Branched-Chain Nomenclature

• Alkyl Groups groups of atoms that are formed
  when one hydrogen is removed from an alkane
  molecule
• Replace the suffix with -yl
• Used in naming branched molecules
• Locate name the parent chain (longest straight
  chain)
• name the alkyl groups in alphabetical order
  giving them the lowest number possible (Read the
  summary on page 698)
• 2-methylpropane
• 2,4-dimethylheptane
• 3-ethyl-2-methylhexane

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Properties Uses of Alkanes

• C-H is a nonpolar bond
• London Dispersion forces are the only
  intermolecular forces
• Strength of London dispersion forces increases as
  mass increases
• Physical States
• 1 to 4 Carbons gas (natural gases)
• 5 to 10 Carbons Liquids (gasoline, kerosene)
• 17 Carbons Solids (paraffin wax)

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Properties Cont.

• Boiling Points increase as mass increases
• Petroleum - mixture of different hydrocarbons
  that varies greatly in composition
• Fractional Distillation - components of a mixture
  are separated on the basis of boiling point, by
  condensation of vapor in a fractionating column
  (p. 713)

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Alkane Nomenclature - Draw the Structure for the
Following

• Hexane
• 2,3-Dimethylbutane
• 2-Methylpentane
• 3-Methylpentane
• 3,3,4-trimethyloctane
• n-propylcyclopentane
• 3-ethyl-2-methylhexane

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Alkenes

• One or more double bonds present between carbon
  atoms (Unsaturated compound)
• Number the parent chain so the double bond gets
  the lowest number
• If more than one double bond is present, use the
  prefix di- before the ene ending.
• 4-ethyl-2-methyl-1-nonene
• 6-methyl-2,3-octadiene

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Alkynes

• At least one Carbon-Carbon triple bond is present
• Unsaturated Compounds
• The same rules apply as for alkenes.

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Structural Isomers

• Compounds that have the same molecular formula
  but different structural formulas (connected
  differently)
• Differ in physical properties and chemical
  reactivity

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Stereoisomers Geometric (Cis-trans) isomers

• For Alkenes only
• because of restricted rotation about a
  carbon-carbon double bond, an alkene with two
  different groups on each carbon of the double
  bond shows cis-trans isomerism

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Stereoisomers Optical isomers

• Pairs of molecules that differ only in the way
  that four different groups are arranged around a
  central C atom.
• They look like mirror images of each other
• They cannot be superimposed on top of each other
• Asymetric carbon A carbon that has four
  different atoms or groups attached to it
• http//www.elmhurst.edu/chm/vchembook/209optical.
  html

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Hydrocarbon Rings

• Cycloalkanes (cyclic hydrocarbons) - carbon atoms
  are arranged in a ring
• General Formula - CnH2n
• Aromatic compounds (arenes) bonding e- between
  Carbons are shared equally around the ring (ex.
  benzene)

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Cycloalkane Nomenclature

• Add the prefix cyclo to the parent chain
• Add the names of the alkyl groups
• the carbon atoms so that the lowest number goes
  to the alkyl group that comes first in
  alphabetical order
• Insert position numbers
• Punctuate the Name
• 1-ethylcyclopentane
• 1-n-butyl-4-ethylcyclohexane

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Functional Groups - Chapter 23

• Sites of chemical reactivity
• See Text for Nomenclature Rules for each type of
  functional group
• See Text for General Uses for each type of
  compound.
• http//michele.usc.edu/105b/organic/funcgroups.htm
  l
• http//chemed.chem.purdue.edu/genchem/topicreview/
  bp/2organic/2org_frame.html
• http//en.wikipedia.org/wiki/Functional_group

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alcohols R OH amines R NH2
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Ethers

• R-O-R

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REVIEW MATERIAL

• Electron Configurations - 133
• Molecular Geometry - 232
• Hybridization 234
• Intermolecular Forces - 240
• Electronegativity - 177, 238
• Lewis Dot Structures 188, 218

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Electronegativity Differences

• Nonpolar 0 - 0.4
• Polar Covalent 0.4 2.0
• Ionic Bonds 2.0