Introduction to Organic Chemistry and Alkanes

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Introduction to Organic Chemistry and Alkanes
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Organic Chemistry

• Molecules made up of carbon, hydrogen, and a few
  other elements (oxygen, nitrogen, sulfur, or
  halogens)
• Amazing array of organic molecules
• Many are essential to life (phospholipids and
  enzymes)
• Glucose and fructose
• Penicillin and aspirin
• Fossil fuels

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Why so many Organic Compounds?

• Carbon can form stable, covalent bonds with other
  carbon atoms.
• 3 allotropes of carbon (forms of an element
  that have the same physical state but different
  properties)
• 1. Diamond
• 2. Graphite
• 3. Buckminsterfullerene

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3 Allotropes of Carbon

• 1. Diamond
• A large 3-dimensional network
• of carbon-to-carbon bonds
• results in an extremely
• hard substance

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3 Allotropes of Carbon

• 2. Graphite
• -Planar layers of carbon-to-carbon bonds that
  extend in 2-dimensions
• -Planar units slide over one another

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3 Allotropes of Carbon

• 3. Buckminsterfullerene - Buckey Ball
• -60 Carbon atoms in the shape of a soccer ball
• -discovered in the 1980s

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Why so many Organic Compounds?

• II. Carbon can form stable bonds with other
  elements.
• -Several families of organic compounds contain
  oxygen atoms bonded to carbon. Others contain
  nitrogen, sulfur or halogens.
• -The presence of these elements allows for a
  wide variety of new chemical and physical
  properties on the organic compound.

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Why so many Organic Compounds?

• III. Carbon can form double or triple bonds with
  other Carbon atoms.
• This produces a variety of organic molecules
  with very different properties.

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Why so many Organic Compounds?

• IV. The structure of the compounds creates
  limitless possibilities.
• The number of ways in which carbon and other
  atoms can be arranged is nearly limitless. (Ex
  linear chains, ring structures, and branched
  chains).

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Isomers

• ISOMERS - same number and kinds of atoms but with
  different structures, therefore different
  properties
• STRUCTURE determines FUNCTION

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Comparison of Organic and Inorganic Compounds
Property Organic Inorganic
Bonding Covalent Ionic
Terms to describe Molecule Compound
Physical state Gas Solid
Boiling Point Low High
Melting Point Low High
Solubility in water Insoluble High
Solubility in organic solvents High Insoluble
Flammable Yes No
Conducts electricity No Yes (soln and liq)
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Families of Organic Compounds
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Families of Organic Compounds
Hydrocarbon contains only hydrogens and
carbon Substituted Hydrocarbon -
one or more hydrogen atoms is replaced by
another atom or group of atoms (functional
group)
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Families of Organic Compounds
Aliphatic Hydrocarbon - alkanes, alkenes,
alkynes Saturated Hydrocarbon -
alkanes contain only C and H have only single
bonds Unsaturated Hydrocarbon alkenes
alkynes contain only C and H have at least
one carbon to carbon double or triple bond
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Families of Organic Compounds
Cycloalkane carbon atoms bonded to one
another to produce a ring Aromatic Hydrocarbon
contains a benzene ring (6 carbon atoms
bonded to one another with alternating single
and double bonds to form a ring)
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Common Functional Groups
                                               
                    
Structure determines Function
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Three types of formulas

• Molecular formula gives the type and number of
  each atom present in a molecule but does not show
  bonding pattern
• EXAMPLE C3H8
• Structural formula shows each atom and bond in
  a molecule
• EXAMPLE
• Condensed formula shows all the atoms and
  places them in sequential order that indicates
  which atoms are bonded to which
• EXAMPLE CH3CH2CH3

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Another way to draw structures

• Line or skeletal structure
• Only the bonds and not the atoms are shown.
• A carbon atom is assumed to be at the ends and
  junctions of the lines
• Correct number of hydrogens is mentally supplied

Cl
3-methylpentane
3-chloropentane
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Alkyl Groups
Number of carbons Name
1 Methyl
2 Ethyl
3 Propyl
4 Butyl
5 Pentyl
6 Hexyl
7 Heptyl
8 Octyl
9 Nonyl
10 Decyl
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Carbons are classified according to the number of
other carbons to which they are attached.

• Primary (1) bonded to one other carbon
• Secondary (2) bonded to two other carbons
• Tertiary (3) bonded to three other carbons

H C-C- H
C H-C-C H
C C-C- C
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I.U.P.A.C. Nomenclature

• International Union of Pure and Applied Chemistry
  organization responsible for establishing and
  maintaining a standard, universal system for
  naming compounds
• All alkanes are the alkyl group name followed
  with the suffix ane.

Contains 3 carbons propyl group Add ane
Propane
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Nomenclature of Alkanes

• Find the parent chain.
• Find the longest continuous chain of carbon atoms
  present in the molecule, and use the name of that
  chain as the parent name.
• CH3CH2CH2CHCH3 CH2CH3
• CH2CH3 CH3CHCHCH2CH3
• CH2CH2CH3

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Nomenclature of Alkanes

• 1. Find the parent chain.
• B. If two different chains of equal length are
  present, choose the one with the larger number
  of branches.
• CH3
• CH3CHCHCH2CH2CH3
• CH2CH3

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Nomenclature of Alkanes

• Number the atoms in the main chain.
• Beginning at the end nearer the first branch
  point, number each carbon atom in the parent
  chain.
• CH2CH3
• CH3CHCHCH2CH3
• CH2CH2CH3

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Nomenclature of Alkanes

• Number the atoms in the main chain.
• B. If there is branching an equal distance
  away from both ends of the parent chain, begin
  numbering at the end nearer the second branch
  point.
• CH3CH2 CH3 CH2CH3
• CH3CHCH2CH2CHCHCH2CH3

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Nomenclature of Alkanes

• Identify and number the substituents.
• Assign a number to each substituent according to
  its point of attachment to the main chain.
• B. If there are two substituents on the same
  carbon, assign them both the same number.
  There must be as many numbers in the name as
  there are substituents.

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Nomenclature of Alkanes

• 3. Identify and number the substituents
• CH3
• CH3CH2CCH2CH2CH3
• CH2
• CH3

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Nomenclature of Alkanes

• Write the name as a single word, using hyphens to
  separate the different prefixes and using commas
  to separate numbers.
• If two or more different substituents are
  present, cite them in alphabetical order.
• If two or more identical substituents are
  present, use one of the prefixes di-, tri-,
  tetra-, etc but do NOT use these for
  alphabetizing purposes.

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Name These Alkanes!

• CH2CH3
• CH3CH2CH2CHCH3
• CH3
• CH3CHCHCH2CH2CH3
• CH2CH3

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Name These Alkanes!

• CH2CH3 CH3 CH2CH3
• CH3CHCH2CH2CHCHCH2CH3
• CH3
• CH2
• CH3CHCHCH2CH3
• CH2CH2CH3

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Name These Alkanes!

• CH3
• CH3CH2CCH2CHCH3
• CH2
• CH3

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Nomenclature for HALOGENATED ALKANES

• Step 1 name the parent chain
• CH3CHCH3
• Br
• propane
• Step 2 number the parent chain
• CH3CHCH3
• Br
• 1 2 3

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Nomenclature for HALOGENATED ALKANES

• Step 3 name number each ATOM or GROUP
  attached to the parent (the substituent)
• CH3CHCH3
• Br
• parent propane
• substituent 2-bromo

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Nomenclature for HALOGENATED ALKANES

• Step 4 If the same substituent occurs more than
  once, a separate number AND a prefix (di, tri,
  tetra-, etc.) are used
• Br Br
• CH3CHCH2CH2CHCH3
• Parent hexane
• Substituent 2,5-dibromo

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Nomenclature for HALOGENATED ALKANES

• Step 5 Place the names of the branches in
  alphabetical order before the parent name.
• Separate numbers with commas
• Separate names numbers with hyphens
• HALOGEN substituents are placed BEFORE alkyl
  substituents in the name

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Nomenclature for HALOGENATED ALKANES

• CH3
• CH3 CH C CH2CH3
• Br CH3
• Parent pentane
• Subs 2-bromo
• 3,3-dimethyl
• 2-bromo-3,3-dimethylpentane

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Practice

• 1) CH3CH2CH2CH2CHCH3
• Br
• 2) CH2CHCH2
• Br Br Br

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Practice

• 3) Br
• HCH
• CH3CCH2Br
• CH3
• 4) CH3CHCH2CH2CHCH2Br
• Cl CH3

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Practice

• 5) CH3CHCHCH2CH2CH2Cl
• CH3