Hydrocarbons

1
Hydrocarbons

• The basis for organic chemistry

2
Organic Compounds

• Contain C bonded to other elements, commonly H,
  O, N, S, and halogens
• Carbon
• Can form many different compounds due to its
  hybrid orbitals
• Has intermediate electonegativity, so its most
  likely to form molecular compounds (Recall
  molecular compounds have diverse properties)
• Can make single, double, and triple bonds
• Can form isomers (same molecular formula but
  different arrangement of atoms)

3
Types of Hydrocarbons

• Saturated Contain the maximum number of
  hydrogens, single bonds between all carbons
• Unsaturated Contain 1 double or triple bonds

4
Types of Hydrocarbons

• Aliphatic Carbons are arranged in chains
• Cyclic Carbons are arranged in rings
• Aromatic Contain a benzene ring

5
Types of Hydrocarbons
6
Structural Shorthand
Explicit hydrogens (those required to complete
carbons valence) are usually left off of
drawings of hydrocarbons
C1
C2
C3
C4
C1
C3
C4
C2
Line intersections represent carbon atoms
7
Cyclic Alkanes
Cyclopropane, C3H6
Cyclobutane, C4H8
Cyclopentane, C5H10
Cyclohexane, C6H12
Cycloheptane, C7H14
Remember, explicit hydrogens are left out
8
Hydrocarbon Root Names
of Carbons Root Name
1 meth-
2 eth-
3 prop-
4 but-
5 pent-
6 hex-
7 hept-
8 oct-
9 non-
10 dec-
9
Naming Alkanes

• Based off the number of C atoms in the longest
  chain
• Count the number of Cs in the longest chain
• Determine the appropriate root
• Add the suffix ane

10
Rules for Naming Alkanes (Nomenclature)

• For a branched hydrocarbon, the longest
  continuous chain
• of carbon atoms gives the root name for the
  hydrocarbon

1
2
3
4
4 carbon chain butane
11
Naming Branched Alkanes

• Based off the number of C atoms in the longest
  chain
• Count the number of Cs in the longest chain
• Determine the appropriate root
• Use the numbered Cs to give the branches a
  position number add yl suffix
• Add the suffix ane

12
Naming Branched Alkanes

• Important Rules
• Start numbering from the end that will give you
  the lowest number of branches
• If there is more than one type of branch, name
  the branches in alphabetical order
• If there is more than two of the same type of
  branch, give the branch a position number and
  prefixes di, tri tetra etc.
• Put commas between numbers and hyphens between
  numbers and letters

13
Rules for Naming Alkanes (Nomenclature)

• When alkane groups appear as substituents, they
• are named by dropping the -ane and adding -yl.

CH3 Methyl
CH2CH3 Ethyl
CH2CH2CH3 Propyl
CH2CH2CH2CH3 Butyl
Methyl
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Rules for Naming Alkanes (Nomenclature)

• The positions of substituent groups are specified
• by numbering the longest chain of carbon atoms
• sequentially, starting at the end closest to the
• branching.

1
2
3
4
Methyl
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Rules for Naming Alkanes (Nomenclature)

• The location and name of each substituent are
• followed by the root alkane name. The
  substituents
• are listed in alphabetical order (irrespective of
  any
• prefix), and the prefixes di-, tri-, etc. are
  used to
• indicate multiple identical substituents.

1
2
3
4
Name
2-methylbutane
Methyl
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Nomenclature Practice
Name this compound
1
9 carbons nonane
2
4
3
5
6
7
8
9

• Step 1 For a branched hydrocarbon, the longest
  continuous chain of carbon atoms gives the root
  name for the hydrocarbon

17
Nomenclature Practice
Name this compound
9 carbons nonane
1
2
4
3
5
6
CH3 methyl
7
chlorine chloro
8
9
Step 2 When alkane groups appear as
substituents, they are named by dropping the -ane
and adding -yl.
18
Nomenclature Practice
Name this compound
9 carbons nonane
1
2
4
3
5
6
CH3 methyl
7
chlorine chloro
8
9
1
9
NOT
9
1

• Step 3 The positions of substituent groups are
  specified by numbering the longest chain of
  carbon atoms sequentially, starting at the end
  closest to the branching.

19
Nomenclature Practice
Name this compound
9 carbons nonane
1
2
4
3
5
6
CH3 methyl
7
chlorine chloro
8
9
2-chloro-3,6-dimethylnonane

• Step 4 The location and name of each
  substituent are followed by the root alkane name.
  The substituents are listed in alphabetical order
  (irrespective of any prefix), and the prefixes
  di-, tri-, etc. are used to indicate multiple
  identical substituents.

20
Practice

• P. 11-16 1, 2
• Naming Alkanes Worksheet
• Alkane Challenge Worksheet

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Naming Alkenes Alkynes

• Count the number of Cs in the longest chain
  containing the double/triple bond.
• This is the parent chain, determine the root
• Number the parent chain so that the double/triple
  bond has the lowest possible position number
• Identify the position numbers of branches
• Same rules as before
• Write the branches in alphabetical order
• Write the root, including a prefix that
  identifies the position of the double/triple bond
• Add the prefix cyclo if its cyclic
• Add the suffix ene or yne

22
Naming Alkenes Alkynes
23
Structural Isomers

• Structural isomers are compounds with the same
  molecular formula but different structural
  arrangements
• They will have different physical and chemical
  properties
• Example
• pentane
• 2-methylbutane
• 2,2-dimathylpropane

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Cis-Trans Isomers

• Cis-trans isomers occur when different groups of
  atoms are arranged around a double bond
• Unlike a single C-C bond that can rotate, the
  double CC bond is fixed

Opposite side
Same side
cis-1,2-dichloroethene
trans-1,2-dichloroethene
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Cis-Trans Isomers

• Examples
• cis-3-pentene
• trans-2-hexene

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Naming Aromatics

1. Same rules
2. If benzene is the parent chain benzene suffix
3. If benzene is a branch group phenyl

27
Practice

• P. 16-22 3-7, 8abc
• Naming Alkenes/Alkynes Worksheet
• Isomer Challenge Worksheet
• Naming Hydrocarbons Worksheet