Transcript Hydrocarbons

Hydrocarbons
The basis for organic chemistry
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)
Types of Hydrocarbons
• Saturated: Contain the maximum number of
hydrogens, single bonds between all carbons
• Unsaturated: Contain 1+ double or triple
bonds
Types of Hydrocarbons
• Aliphatic Carbons are arranged in chains
• Cyclic: Carbons are arranged in rings
• Aromatic: Contain a benzene ring
Types of Hydrocarbons
Name
Alkane
Alkene
Alkyne
Definition
Hydrocarbon with only
single bonds between
carbon atoms.
Hydrocarbon with at
least one double bond.
Hydrocarbon with at
least one triple bond.
General
Formula
CnH2n+2
CnH2n
CnH2n-2
Structural Shorthand
Explicit hydrogens (those required to complete
carbon’s valence) are usually left off of
drawings of hydrocarbons
H
CH3
H
H
H
H3C
H
C1 C2 C3 C4
H
H
H
H
H
C1 C2 C3
C4
Line intersections represent carbon atoms
Cyclic Alkanes
Cyclopropane, C3H6
Cyclobutane, C4H8
Cyclopentane, C5H10
Cyclohexane, C6H12
Cycloheptane, C7H14
Remember, explicit hydrogens are left out
Hydrocarbon Root Names
# of Carbons
1
2
3
4
5
6
7
8
9
10
Root Name
methethpropbutpenthexheptoctnondec-
Naming Alkanes
Based off the number of C atoms in the
longest chain
1. Count the number of C’s in the longest chain
2. Determine the appropriate root
3. Add the suffix “ane”
Rules for Naming Alkanes
(Nomenclature)
For a branched hydrocarbon, the longest continuous chain
of carbon atoms gives the root name for the hydrocarbon
H3C1
2
H3C
3
4
CH3
4 carbon chain = butane
Naming Branched Alkanes
Based off the number of C atoms in the
longest chain
1. Count the number of C’s in the longest chain
2. Determine the appropriate root
3. Use the numbered C’s to give the branches a
position number add “yl” suffix
4. Add the suffix “ane”
Naming Branched Alkanes
Important Rules:
1. Start numbering from the end that will give you
the lowest number of branches
2. If there is more than one type of branch, name
the branches in alphabetical order
3. If there is more than two of the same type of
branch, give the branch a position number and
prefixes “di”, “tri” “tetra” etc.
4. Put commas between numbers and hyphens
between numbers and letters
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
H3C
H3C
Methyl
CH3
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.
H3C1
2
3
H3C
Methyl
4
CH3
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.
H3C1
2
3
H3C
Methyl
4
CH3
Name: 2-methylbutane
Nomenclature Practice
Name this compound
CH3
H3C1 2
Cl
3 4
5
CH3
6
7
9 carbons = nonane
8
H3C9
Step #1: For a branched hydrocarbon, the longest
continuous chain of carbon atoms gives the root name
for the hydrocarbon
Nomenclature Practice
Name this compound
CH3
H3C1 2
Cl
3 4
5
CH3
6
7
9 carbons = nonane
CH3 = methyl
8
chlorine = chloro
H3C9
Step #2: When alkane groups appear as substituents, they
are named by dropping the -ane and adding -yl.
Nomenclature Practice
Name this compound
CH3
H3C1 2
Cl
3 4
5
6
7
9 carbons = nonane
CH3
CH3 = methyl
chlorine = chloro
8
H3C9
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.
Nomenclature Practice
Name this compound
CH3
H3C1 2
Cl
3 4
5
CH3
6
7
9 carbons = nonane
CH3 = methyl
8
chlorine = chloro
H3C9
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.
Practice
• P. 11-16 #1, 2
• Naming Alkanes Worksheet
• Alkane Challenge Worksheet
Naming Alkenes & Alkynes
1. Count the number of C’s 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
2. Identify the position numbers of branches
•
Same rules as before
3. Write the branches in alphabetical order
4. Write the root, including a prefix that identifies the
position of the double/triple bond
•
Add the prefix “cyclo” if its cyclic
5. Add the suffix “ene” or “yne”
Naming Alkenes & Alkynes
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
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 C=C bond is fixed
Same
side
Opposite
side
cis-1,2-dichloroethene
trans-1,2-dichloroethene
Cis-Trans Isomers
Examples:
• cis-3-pentene
• trans-2-hexene
Naming Aromatics
1. Same rules
2. If benzene is the parent chain “benzene” suffix
3. If benzene is a branch group “phenyl”
Practice
•
•
•
•
P. 16-22 #3-7, 8abc
Naming Alkenes/Alkynes Worksheet
Isomer Challenge Worksheet
Naming Hydrocarbons Worksheet