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Section 9.2 (pg. 366-374)
Naming Organic
Compounds Today’s Objectives:
1) Name and draw structural, condensed structural, and line diagrams and
formulas for saturated and unsaturated aliphatic (including cyclic)
• Containing up to 10 carbon atoms in the parent chain/cyclic structure
• Containing only one type of a functional group or multiple bond
• Using the IUPAC nomenclature guidelines
2) Identify types of compounds from the functional groups, given the structural
formula
3) Define structural isomerism and relate to variations in properties
Four Types of Formulas
1. Molecular Formulas C5H10(g) Not very useful for organic
compounds because so many
isomers can exist
2. Structural Formulas
1. Condensed Structural Formulas
2. Line Diagrams
– end of line segment represents carbon
– it is assumed to satisfy each carbon’s octet
Naming Organic Compounds
Aliphatic Hydrocarbons – contains only hydrogen and carbon atoms
Straight line chains of carbon atoms
Alicyclic hydrocarbons have carbon atoms forming a closed ring. Still
considered aliphatic
Alkanes Alkenes Alkynes
Only single C-C
bonds
Double C-C Bond
present
Triple C-C bond
present
General formula
CnH2n+2
General formula:
CnH2n
General formula:
CnH2n-2
Saturated Unsaturated Unsaturated
In organic chemistry, names
have a root and a suffix.
The root describes the number
of carbons present in the chain
or ring.
The suffix describes the type of
compound it is.
Naming Organic Compounds
Naming Organic Compounds
Naming ALKANES
1. Find the parent chain (the longest continuous chain
of carbon atoms). Use the appropriate root and
the suffix-ane.
Naming ALKANES
1. Find the parent chain. Use the appropriate root and suffix.
2. Number the carbon atoms, starting from the end closest to the
branch(es) so that the numbers are the lowest possible
3. Identify any branches and their location number on the parent chain
(us the suffix –yl for branches)
4. Write the complete IUPAC name, following the format: (number of
location, if necessary) – (branch name) (parent chain)
2-methylheptane
If more than one of the same branch exist, use a multiplier to
show this (di, tri). Remember to include all numbers
Draw 2,4,6-trimethylheptane
Naming ALKANES
If different branches exist, name them in alphabetical order
ethyl before methyl (e before m in the alphabet)
Naming ALKANES
If there is more than one
branch of the same type, a
locating number is given to
each branch and a prefix
indicating the number of that
type of branch is attached to
the name.
This numbering prefix does
not affect the alphabetical
order of the branches
Draw the structural formula
for 3,4-dimethylhexane
Naming ALKANES
Summary of Naming Alkanes
1. Find the parent chain. Use the appropriate root and suffix.
2. Number the parent chain carbon atoms, starting from the end
closest to the branch(es) so that the numbers are the lowest
possible
3. Identify any branches and their location number on the
parent chain (us the suffix –yl for branches)
4. If more than one of the same branch exist, use a multiplier
(di, tri) to show this. Remember to include all numbers
5. If different branches exist, name them in alphabetical order
6. Separate numbers from numbers using commas, and
numbers from words using dashes (no extra spaces)
Don’t forget
Questions will specifically
ask about structural,
condensed structural or
line structural formulas.
You must be comfortable
drawing any of the three
Practice
Write the IUPAC name for the following
2,5-dimethyl-4-propyloctane
Correct the following names:
4-ethyl-2-methylpentane
ACTUALLY 2,4-dimethylhexane
ALWAYS LOOK FOR LONGEST CHAIN!!
Correct the following name:
4,5-dimethylhexane
Actually 2,3-dimethylhexane
**Want branch numbers to be as low as possible
CYCLOALKANES
Based on evidence, chemists believe that organic carbon compounds
sometimes take the form of cyclic hydrocarbons:
Cycloalkanes: Alkanes that form a closed ring
General Formula CnH2n
Two less hydrogens are present than in straight chain alkanes because
the two ends of the molecule are joined
Are these considered saturated?? Yes, because they have only single
bonds and the max amount of hydrogen's bonded to the carbons
Cyclo-compounds will have a higher boiling point than their straight
chain partners (because there is an additional bond present)
Cycloalkanes are named by placing the prefix cyclo in front
of the alkane name, as in cyclopropane and cyclobutane
If branches are present, treat the cycloalkane as the parent
chain and identify the branches.
Since there is no end at which to start the numbering, use the
lowest numbers possible
Naming CYCLOALKANES
Name the following:
1. 2.
1,2-dimethylcyclopentane ethylcyclohexane
**Why don’t we need a number?
Today’s homework
Pg. 370 #7 (a-c) ,9, 10 (a-b) 11 (a-c)
Pg. 372 #5-6
What is coming up tomorrow?
Naming Alkenes, Alkynes, Cycloalkenes and
Cycloalkynes
Comparing properties of Isomers
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