Transcript Alkanes, Alkenes, Alkynes

Simple Organic Chemistry
Basic Structure and Nomenclature
Graphic: www.lab-initio.com
First Ten Alkanes
Formula Name
Formula Name
CH4
Methane
C6H14
Hexane
C2H6
Ethane
C7H16
Heptane
C3H8
Propane
C8H18
Octane
C4H10
Butane
C9H20
Nonane
C5H12
Pentane
C10H22
Decane
Alkane = CnH2n+2
Straight Chain Alkanes aren’t “Straight”
C – C bonds are sp3 hybridized
CH3
H3C
Butane, C4H10
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
Structural Isomers
Isomers are molecules with the same chemical
formula, but different organization of atoms
(different bonding)
n-Pentane, C5H12
Isopentane, C5H12
H3C
CH3
H3C
CH3
CH3
Neopentane, C5H12
CH3
H3C
CH3
CH3
Newman Projections
Rotation can occur around C – C single bonds
Ethane, C2H6
HH
H
H
A Eclipsed
HH
H
B Staggered
E
H
H
H
0
60
120
180
240
Degrees of Rotation 
H
H
300
360
Newman Projections
Butane, C4H10
H3C
CH3
Cyclic Alkanes
Cyclopropane, C3H6
Cyclobutane, C4H8
Cyclopentane, C5H10
Cyclohexane, C6H12
Cycloheptane, C7H14
Remember, explicit hydrogens are left out
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
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.
Alkenes Contain Carbon-Carbon
Double bonds
1  bond
H
H
C
H
H
C
H
C
H
H
C
H
Ethene
1  bond
Alkynes Contain Carbon-Carbon
Triple Bonds
H
H
C
C
C
1  bond
C
Ethyne
1  bond
H
1  bond
H
Reactions of Alkenes and Alkynes
Hydrogenation
CH 2  CHCH 3  H 2   CH 3 CH 2 CH 3
Propene
Propane
Catalyst
Halogenation
CH 2  CHCH 2 CH 2 CH 3  Br2  CH 2 BrCHBrCH 2 CH 2 CH 3
1-Pentene
1-2-dibromopentene
Polymerization
Small molecules are joined together to form
a large molecule
CH2 CH2
Polyethylene
n
Aromatic Hydrocarbons
Cyclic unsaturated hydrocarbons with
delocalized electrons
The simplest aromatic hydrocarbon is
benzene (C6H6)
H
H
H
H
H
H
H
H
H
H
H
OR…
H
H
H
H
H
H
H
Geometric Isomerism in Aromatics
ortho (o-) = two adjacent
substituents
o-dichlorobenzene
Cl
H
Cl
H
H
H
meta (m-) = one carbon between
substituents
m-dichlorobenzene
para (p-) = two carbons between
substituents
p-dichlorobenzene
Cl
H
H
Cl
H
H
Cl
H
H
H
H
Cl
Hydrocarbon Derivatives
Class
Alcohol
Functional Group
hydroxyl group
General Formula
-O — H
R – OH
Alkyl halide
—X
R—X
Ether
—O—
R — O — R’
Aldehyde
carbonyl group
O
||
—C—H
O
||
R—C—H
Ketone
carbonyl group
O
||
—C—
O
||
R — C — R’
Carboxylic acid
carboxyl group
O
||
— C — OH
Ester
Amine
amine group
O
||
— C — OH
O
||
— C — O—
O
||
R — C — O — R’
|
—N—
R’
|
R — N — R’’