Transcript No Slide Title

Structure
• Hydrocarbon: a compound composed only
of carbon and hydrogen
• Saturated hydrocarbon: a hydrocarbon
containing only single bonds
• Alkane: a saturated hydrocarbon whose
carbons are arranged in a chain
• Aliphatic hydrocarbon: another name for an
alkane
Structure
• Shape
– tetrahedral about carbon
– all bond angles are approximately
109.5°
Nomenclature
• Alkanes have the general formula CnH2n+2
Name
Mol ecu l ar
Form u la
C on de ns e d
S tru ctu ral Formu l a
CH4
C2 H6
CH4
CH3 CH3
bu tan e
C3 H8
C4 H10
CH3 CH2 CH3
CH3 (CH 2 ) 2 CH3
pe n tan e
C5 H12
CH3 (CH 2 ) 3 CH3
h e xan e
C6 H14
CH3 (CH 2 ) 4 CH3
h e ptan e
C7 H16
CH3 (CH 2 ) 5 CH3
me th an e
e th an e
propan e
Nomenclature
• Alkanes (contd.)
octan e
C8 H18
CH3 (CH 2 ) 6 CH3
n on an e
C9 H20
CH3 (CH 2 ) 7 CH3
de can e
C10 H22
C12 H26
CH3 (CH 2 ) 8 CH3
dode can e
tetrade can e C14
h e xade can e C16
octadecan e C18
C20
e icosan e
H30
H34
H38
H42
CH3 (CH 2 ) 10 CH3
CH3 (CH 2 ) 12 CH3
CH3 (CH 2 ) 14 CH3
CH3 (CH 2 ) 16 CH3
CH3 (CH 2 ) 18 CH3
Constitutional Isomerism
• Compounds isomers: compounds with the
same molecular formula but a different
connectivity (order of attachment of their
atoms)
– example: C4H10
CH3
CH3 CH2 CH2 CH3
Bu tan e
CH3 CHCH 3
2-Meth ylpropan e
Constitutional Isomerism
Mol e cu l ar Con s ti tu tion al
Form u la Isome rs
CH4
C5 H12
C10 H22
1
3
75
C15 H32
4,347
C30 H62 4,111,846,763
World population
is about
6,000,000,000
Nomenclature
• International Union of Pure and Applied
Chemistry (IUPAC)
• Prefix tells the number of carbon atoms
• Suffix -ane specifies an alkane
Nomenclature
• IUPAC system
Prefi x C arbon s
me th 1
e th 2
prop3
bu t4
pe n t5
h e x6
7
h e ptoct8
n on 9
de c10
Prefi x C arbon s
u n de c11
dode c12
tri dec13
tetrade c- 14
pe n tade c- 15
h e xade c- 16
h e ptade c- 17
octadec18
n on ade c- 19
e icos 20
Nomenclature
• Parent name of the longest carbon chain is
“alkane”
• Groups attached to the parent chain are
called substituents
• Each substituent is given a name and a
number
– If substituent occurs more than once, di-, tri-,
tetra-, etc.
Nomenclature
• Number the chain to give the substituent
encountered first the lowest number
• If there are different substituents, list them
in alphabetical order. The following are not
included in alphabetization.
– di-, tri-, tetra-, etc.
– hyphenated prefixes, such as sec- and tert-
Nomenclature
• Alkyl groups
Name
me th yl
C on de ns e d
S tru ctu ral Formu l a
-CH 3
e th yl
-CH 2 CH3
propyl
-CH 2 CH2 CH3
i sopropyl
-CHCH 3
CH3
Nomenclature
• Alkyl groups
Name
C on de ns e d
S tru ctu ral Formu l a
bu tyl
-CH 2 CH2 CH2 CH3
i sobu tyl
-CH 2 CHCH 3
CH3
s ec-bu tyl
-CHCH 2 CH3
CH3
CH3
tert-bu tyl
-CCH 3
CH3
Nomenclature
• Alkyl groups
Name
C on de ns e d
S tru ctu ral Formu l a
pe n tyl
-CH 2 CH2 CH2 CH2 CH3
i sope n tyl
-CH 2 CH2 CHCH 3
CH3
CH3
n e ope n tyl
-CH 2 CCH 3
CH3
Nomenclature
1. The general name of an open-chain satuated
hydrocarbon is alkane
2. For branched-chain hydrocarbons, the
alkane corresponding to the longest chain is
taken as the parent chain and its name is the
root name
3. Groups attached to the parent chain are
called substituents. Each is given a name
and a number
CH3
1
2
3
CH3 CHCH 3
2-Meth ylpropan e
Nomenclature
4. If there is more than one substituent,
number from the end of th chain that gives
the substituent encountered first the lower
number
5
4
3
CH3
2
1
CH3 CH2 CH2 CHCH 3
2-Me th yl pe n tan e
Nomenclature
5. If the same substituent occurs more than
once, the number of each carbon of the
parent chain on which it occurs is given and
the number of times it occurs is shown by
di-, tri-, tetra-, etc.
1
CH3
CH3
2
4
3
5
CH3 CHCH 2 CHCH 3
2,4-Dim ethylpe ntane
6. If there are two identical substituents,
number the chain to give the lower number
to the substituent encountered first
Nomenclature
7. If there are two or more different
substituents, list them in alphabetical order,
and number from the end of the chain that
gives the substituent encountered first the
lower number
1
2
CH3
3
4
5
6
7
CH3 CH2 CHCH 2 CHCH 2 CH3
CH2 CH3
3-Eth yl -5-me th ylh e ptan e
Nomenclature
8. The prefixes di-, tri-, tetra- etc. are not
included in alphabetization
CH3 CH2 CH3
1
2 3
4
5
6
CH3 CCH2 CHCH 2 CH3
CH3
4-Eth yl -2,2-dim e th ylh e xan e
9. Neither are italicized prefixes such as secand tert-.
Classification of C & H
• Primary (1°) C: a carbon bonded to one
other carbon
– 1° H: a hydrogen bonded to a 1° carbon
• Secondary (2°): a carbon bonded to two
other carbons
– 2°H: a hydrogen bonded to a 2° carbon
• Tertiary (3°) C: a carbon bonded to three
other carbons
– 3° H: a hydrogen bonded to a 3° carbon
• Quaternary (4°) C: a carbon bonded to four
other carbons
Cycloalkanes
• General formula CnH2n
• Structure and nomenclature
– to name, prefix the name of the corresponding
open-chain alkane with cyclo-, and name each
substituent on the ring
– if only one substituent, no need to give it a
number
– if two or more substituents, number from the
substituent of lowest alphabetical order
– where there is choice, number to give
substituents the lowest set of numbers
Cycloalkanes
• Line-angle drawings
– each line represents a C-C bond
– each angle represents a C
H2 C
CH2
CH
H2 C
CH2
CH3
CH
CH3
C C
C
C
C
C C
C
Cycloalkanes
• Examples: name these cycloalkanes
a)
b)
c)
d)