1 sch4u - introduction to organic chemistry...
TRANSCRIPT
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SCH4U - Introduction to
Organic Chemistry*S*T*A*R*R*I*N*G*
The ALKANESThe ALKENES
The ALKYL GroupsThe Aromatic Compounds
And all Their Little ISOMERS !
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And Co-Starring
*S T R U C T U R E S*and
F o r m u l a s
With special mention toThe International Union of Pure
and Applied Chemistry
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Structural Features of Carbon Compounds
• The compound may be open-chained or cyclic.• Chains may be straight or branched.• May be saturated or unsaturated.• Rings can be carbocyclic or heterocyclic.
• You will be dealing with ALL these cases at one time or another in this class!
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Structures and Chemical Formulas • Molecular formulas are only useful for the very
simplest compounds such as CH4 or C2H6, since they give no information on how atoms connect.
• There is usually more than one way to arrange the atoms listed in the molecular formula
• Expanded molecular formulas show atoms in the order that they appear, with brackets to indicate groups attached to chains.
– ie) CH3C(CH3)2CH2CH3
More ways to represent...
Organic compounds can be very complex! • A system is needed that shows structure.
Skeleton structuresExpanded structures (full structural formulas)Condensed structural formulasLine representations
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Skeleton Structures• Skeleton structure or skeleton formula
• Leaves out the hydrogen atoms.• For hydrocarbons, only the carbon skeleton and connecting bonds are
shown.• Bonds are represented as lines. .
• C – Example: Isobutane C-C-C
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Expanded Structural Formulas
• Expanded structural formula• Shows all atoms with bonds.• Bonds are represented as lines
– Example Isobutane
• Also called a full structural formula.
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Condensed Formulas
• Condensed formula• Shorthand way of writing formula.• Lists all atoms in order and tells how they are bound together.• C-H bonds are assumed, not shown– Example: Isobutane
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Line Structural Diagrams
• Line formula or line representation• The end of each line or meeting point represents a carbon atom• Hydrogen not shown, assumed• Zig zag pattern for single and double bonds, triple bonds are in
straight line• Example: Isobutane
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Isomers• Structural Isomers: Compounds with the same
number of atoms and bonds but with different arrangements.– CH3CH2CH2CH2CH3 CH3CH(CH3)CH2CH3 (CH3)4C
Geometric IsomersCompounds which have the SAME molecular formula, but different arrangements of atoms around a double carbon-carbon bond
• These exist when two or more arrangements are possible due to the type of bond.
• Alkanes - can rotate about all bonds– no geometric isomers
• Alkenes - rigid bond– can have geometric isomers
• Alkynes - rigid bond but linear– no geometric isomers
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Geometric Isomers (continued)
There are two possible arrangements
Example 2-butene
C=CH
CH3
H3C
HC=C
CH3
HH
H3C
cis Two methyl groups areon the same side (and
so are the two H’s.
transTwo methyl groups
are on opposite sides.