Introduction to Organic Chemistry

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Chapter 12

• Introduction to Organic Chemistry

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Organic Chemistry

• Organic Chemistry- the study of carbon compounds

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Organic Molecules

• Carbon is tetravalent always 4 bonds
• Comprised of covalent bonds
• Nonpolar
• Polar
• Polarized molecules
• Single, Double, Triple bonds
• Three dimensional shapes (VSEPR)
• Contain H, N, and O in addition to carbon

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Properties of Organic Molecules

• Low melting and boiling points
• Few are soluble in water

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Characterization of Organic Molecules

• Functional Groups
• Characteristic structural feature
• Responsible for chemical behavior
• Compounds with the same functional groups tend to
  undergo similar reactions

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Alkanes and Their Isomers

• Alkanes
• hydrocarbons containing only single bonds
• CnH2n2
• Simplest is methane CH4
• Ethane - C2H6
• Carbon forms the backbone
• Propane - C3H8

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Alkanes and Their Isomers

• C4H10

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Alkanes and Their Isomers

• Straight chain alkanes
• Branched chain alkanes
• Constitutional isomers same molecular formula
  but differing connectivity
• Are different compounds with different properties

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Alkanes and Their Isomers
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Drawing Organic Structures

• Structural Formula shows every atom and every
  bond
• Condensed Structures Shorthand way of drawing
  structures in which C-C bond and C-H bonds are
  understood
• Skeletal Structure (Line drawing) Shows the
  carbon backbone using lines
• The juncture of two lines C atom
• Since C has 4 bonds all Hs are left out as well

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Shapes of Organic Molecules

• Tetrahedral at each carbon with 4 bonds
• 3 carbon backbone yields only one possible
  arrangement 1 type of geometry
• 4 carbon straight-chain backbone infinite of
  geometries rotation around single bond
  conformers
• Primary conformation has the least crowded
  structure

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Naming Alkanes

• Use IUPAC naming
• Three parts
• Prefix specifies location of substituents
• Parent indicates the number of carbon atoms in
  the longest chain
• Suffix identifies what family the molecule
  belongs to.

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Straight Chain Alkanes

• Named according to the of carbon atoms with the
  suffix ane.

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Branched-Chain Alkanes

• Substituents that branch of the main chain are
  alkyl groups.

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Branched-Chain Alkanes

• Methyl and Ethyl groups have only one type of
  hydrogen.
• More complex for larger groups

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Branched-Chain Alkanes

• There are 4 possible substitution patterns

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Branched-Chain Alkanes

• Name the main chain
• Number the atoms in the main chain
• Identify the branching substituents, and number
  each
• If two substituents are on the same C then assign
  the same number to both
• Write the name as a single word
• If more than one substituent is present, cite
  them in alphabetical order
• If two or more identical substituents are
  present, use one of the prefixes di-, tri-,
  tetra-, and so forth, but do not use these
  prefixes for alphabetizing purposes.

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Properties of Alkanes

• Read Section 12.7, you will be asked a question
  on the exam.

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Reactions of Alkanes

• 2 types
• Combustion
• Halogenation

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Cycloalkanes

• Cycloalkanes contain a ring of carbons.

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Cycloalkanes

• Cyclopentane and cyclohexane

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Drawing and Naming Cycloalkanes

• Even condensed structures become awkward when we
  work with large molecules that contain rings.
• A more streamlined way of drawing structures is
  often used in which cycloalkanes are represented
  simply by polygons.

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Naming Cycloalkanes

• Use the cycloalkane name as the parent
• Identify and number the substituents
• Start numbering at the group with alphabetical
  priority
• Number the ring so that the substituents have the
  lowest possible numbers

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Homework

• 12.17, 12.18, 12.19, 12.20, 12.21, 12.23, 12.30,
  12.31, 12.32, 12.33, 12.39, 12.40, 12.41, 12.42,
  12.44, 12.45, 12.46, 12.47, 12.48, 12.49, 12.50,
  12.51, 12.52, 12.53, 12.54, 12.55, 12.56, 12.58,
  12.59, 12.60, 12.66, 12.67, 12.68, 12.70, 12.71,
  12.72