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