Download IUPAC naming of alkanes

CHE2060 2: Simple structures, functional groups
Topics
1.
1.
Drawing molecular structures
Arrow formalism & molecular framework
2.
Introduction to alkanes
3.
4.
5.
6.
7.
8.
9.
Isomers
IUPAC naming of alkanes
Alkyl halides & cycloalkanes
Functional groups: where the action is
Alkenes: hydrocarbons with > one double bond
Alkynes: hydrocarbons with > one triple bond
Alkene isomers: who’s across that double bond?
11. Arenes
12. Organohalogens
13. Using molecular formulas
Daley & Daley, Chapter 2
Organic Nomenclature
& Functional Groups
IUPAC naming introduction
IUPAC naming of n-alkanes
Methane 1 carbon
Ethane
2 carbons
Propane
3 carbons
Butane
4 carbons
Pentane
5 carbons
Hexane
6 carbons
Heptane
7 carbons
Octane
8 carbons
Nonane
9 carbons
Decane
10 carbons
These molecules are simple, & so are their
names…. It will get more complicated.
All alkanes have an –ane suffix.
Each of these alkanes (> 3
carbons) has a cycloversion, a ring, as well.
Alkanes are saturated because each carbon is bonded to four
different atoms. Alkanes have no multiple bonds.
D&D p.73-5, 80-1
Naming branched alkanes?
Ethyl group
(2 carbons)
CH3
CH2 - CH3 7
|
|
H2C - CH - CH - CH - CH3
|
|
methyl group
CH3 - H2C CH3
(1 carbons)
1
Steps to take in naming:
1. Find the longest C chain, here it’s the seven highlighted carbons.
So this is some form of heptane
2. Number the chain starting from the end closes to the first branch point.
Here branches start from the 3rd carbon in from either end, so use alphabetical
order of substituents
If there’s a tie start with the end closest to the next substituent in….
3. Name substituents in alphabetical order, giving the carbon number each is attached to.
Punctuate with dashes between letters & numbers, and commas between numbers
Use prefixes to indicate the number of substituents
3-ethyl-4,5-dimethylheptane
These rules are neatly laid out on pages 81-2 of Daley & Daley.
D&D p.79-87
Example: finding the longest chain
Find the longest carbon chain:
6
1
Identical: 2 substituents
only 1 substituents
• Which choice should you base the name on? Chose the option with the greater number
of substituents; here either of the first two.
• Number from the end closest to a substituent. Number of carbons gives the root name.
• Name and number the substituents: methyl @ carbon 2 and ethyl @ carbon 3.
• String the name together with the proper punctuation. Remember alphabetical order.
3-ethyl-2-methylhexane
D&D p.79-87
Examples: naming branched alkanes
Draw these molecules as line-bond structures:
a) 3-ethyl-3-methylhexane
b) 4-ethyl-2-methylhexane
c) 2,2-dimethylbutane
d) 2,2,3-trimethylbutane
e) 2,2,3,3-tetramethylbutane
b)
c)
a)
d)
e)
D&D p.79-87