1.9 LINE NOTATION
Organic chem models:
http://www.umanitoba.ca/chemistry/c
ourses/chem130/molecules/models.ht
ml
1
RULES FOR LINE NOTATION
1)
The end of any line indicates a carbon atom,
unless another atom is indicated.
2)
Any place where two or more lines meet
represents a carbon atom, unless another
atom is indicated.
3)
Any missing valencies are filled by adding
hydrogens.
4)
All non-carbon atoms are clearly indicated.
5)
Unshared pairs are implied, but not shown.
2
LINE NOTATION
CH3
CH3
CH3CH2CH2CH2CH3
C CH3
CH3
H
CH3
CH3CH2CH CH2
C C CH3
H
H C C CH3
CH3
C C CH2CH3
3
STRUCTURES INVOLVING HETEROATOMS
O
O
N
Cl
There is no carbon
here, another atom
is indicated.
A “heteroatom” is any atom different from
carbon or hydrogen.
“hetero” = different (Greek)
4
1.10 Classification of carbon atoms
C
C
C
C
C
PRIMARY CARBON
SECONDARY CARBON
CONNECTED TO ONE
OTHER CARBON
CONNECTED TO TWO
OTHER CARBONS
C
C
C
TERTIARY CARBON
CONNECTED TO THREE
OTHER CARBONS
C
C
C
QUATERNARY
CARBON
C
C
C
CONNECTED TO FOUR
OTHER CARBONS
5
EXAMPLE
A hydrocarbon containing carbon atoms with
differing degrees of substitution
PRIMARY
QUATERNARY
CH3
TERTIARY
CH3
C
CH CH2 CH3
CH3 CH3
SECONDARY
All of the methyl groups (CH3) are primary.
6
1.11Branched chain alkyl groups
MEMORIZE THESE
7
NAMES OF SOME COMMON ALKYL GROUPS
C1
methyl
CH3
C2
ethyl
CH2CH3
propyl
CH2CH2CH3
isopropyl
CH-CH3
C3
Attached to 2o C of propane
CH3
8
NAMES OF SOME COMMON ALKYL GROUPS
( continued )
C4
butyl
CH2CH2CH2CH3
isobutyl
CH2-CH-CH3
CH3
sec -butyl
CH-CH2-CH3
CH3
tert -butyl
(t -butyl)
Attached to 1o C of isobutane
CH3-CH-CH3
CH3
Attached to 2o C of butane
CH3CH2CH2CH3
CH3
C-CH3
CH3
Attached to 3o C of isobutane
CH3-CH-CH3
CH3
9
SOME GENERALIZATIONS
CH3
chain
CH
CH3
chain ends in two methyl
groups = iso
isopropyl, isobutyl, isopentyl ….
CH3
C
CH3
CH3
tert -butyl
attachment is to the 3o carbon
10
ALPHABETIZATION
one word, no italics
ALPHABETIZE UNDER I
isopropyl, isobutyl, isopentyl …...
italics are ignored
ALPHABETIZE UNDER B
sec - butyl, tert - butyl ….
11
SPECIAL GROUP NAMES ARE OFTEN
CONVENIENT ON A LONG CHAIN
and allowed by the IUPAC
CH3
CH3-CH-CH3
8
9
10
11
CH3-CH-CH2-CH2-CH-CH2-CH2-CH-CH2-CH2-CH3
1
2
3
4
5
6
7
CH2-CH3
Choose...
1. isopropyl
2. sec-butyl
3. isobutyl
4. tert-butyl
12
WHEN MORE THAN ONE CHAIN OF
THE SAME LENGTH IS POSSIBLE :
ALWAYS PICK THE CHAIN WITH THE
MOST SUBSTITUENTS
This will avoid using the special groups
in favor of simpler ones ….
13
1
CH3-CH-CH3
2
3
4
5
6
7
8
9
CH3-CH2-CH-CH2-CH2-CH-CH2-CH2-CH3
CH3CHCH2CH3
6-sec-butyl-3-isopropylnonane
incorrect
What is the correct name?
14
SOME FINAL EXAMPLES
15
If you can name this,
you can name anything!
CH3
CH3
CH3 CH CH2 CH CH2 C
1
2
3
4
CH3 CH
5
CH3
6
CH2
7
CH3
CH2 CH3
8
9
16
ALPHABETIZATION RULES
17
FIVE CASES OF ALPHABETIZATION
CASE 1 arranging order with no prefixes
3-ethyl-2-methylhexane
ethyl before methyl
CASE 2 arranging order with prefixes
multiplier (di) is ignored
5-ethyl-2,3-dimethylnonane
ethyl before methyl
CASE 3 arranging order according to locant number
3-ethyl-4-methylhexane
not
4-ethyl-3-methylhexane
1
2
3 4 5
6
18
….. AND DON’T FORGET
CASE 4
italicized prefixes do not count in alphabetizing
tert -butyl
t -butyl
sec -butyl
CASE 5
alphabetize under B
groups without hyphens DO alphabetize using their
first letter
isopropyl
alphabetize under I
isobutyl
alphabetize under I
19