Organic Naming Rules 2

8/22/2019 Organic Naming Rules 2

1/68

Organic Naming Rules

AP Chemistry 439

For complete Rules go to:

http://www.acdlabs.com/iupac/nomenclature/
http://www.acdlabs.com/iupac/nomenclature/http://www.acdlabs.com/iupac/nomenclature/


2/68

Organic Compounds

Consist of mainly four

elements

Carbon

Hydrogen

Oxygen

Nitrogen


3/68

Why Do We Need a Separate Set

of Rules? Examine some typical organic compounds

CH4

C2H6

Name these using typical covalent rules

Carbon tetrahydride

Dicarbon hexahydride


4/68

So?

That wasnt so bad, right?

How about these:

C4H10

C5H12

See my point?

Tetracarbon decahydride

Pentacarbon ??? hydride


5/68

Isomers

If thats not enough, how about this one:

C

H

H

C

H

H

C

H

H

C

H

H

H H

Formula?

C4H

10

C

H

H

C

H

HC

H

HCH

H

H

H

Formula?

C4H

10

DifferentStructure

Same

Formula


6/68

Overall Problems

Memorizing too manyprefixes for largenumbers

Different chemicalshaving the sameformulas

Keep in mind that thusfar weve only dealtwith TWO differentelements!


7/68

So what to do?

Number of hydrogens is going to be the

same, regardless of isomerism

C

H

H

C

H

H

C

H

H

C

H

H

H HC

H

H

C

H

H

C

H

H

C

H H

C

H

H

H H

C

H

H C HH

C

H

H

C

H H

C

H

H

H

H

CH

H

C5H12C5H12

C5H12


8/68

Solution

Since number of

hydrogens dont change

with isomerism, why

bother naming them?

Name the molecule simply

based on number of

CARBONS

We can always add

prefixes or suffixes later

for differentiation


9/68

Name based on number of

Carbons 1

2

3

4

5

6

7

8

9

10

Methane

Ethane

Propane

Butane

Pentane

Hexane

Heptane

Octane

Nonane

Decane


10/68

Did that Really Help?

C

H

H

C

H

H

HH

C

H

H

HH Carbon tetrahydride becomes: Methane

Dicarbon hexahydride becomes: Ethane

C

H

H

C

H

H

C

H

H

C

H

H

H HC

H

H

C

H

H

C

H

H

C

H

H

CH4

C2H6

Octacarbon ???hydride becomes:

Octane

C8H18


11/68

Branches Straight-chain alkanes (Just C & H with

single bonds) are now easy

C

H

H

C

H

H

C

H

H

C

H

H

H H C4H10 Butane

But how do we deal with branches?

C

H

H

C

H

HC

H

HCH

H

H

H

C4H10 ????


12/68

Rules pt. 2

Identify the longest unbranched

chain ofcarbons

Name it as normal

Identify the branch

Name it but give it a yl

suffix

Put the names of all branchesfirst, then put name of longest

chain


13/68

Example

C

H

H

C

H

HC

H

HCH

H

H

HLongest unbranched

chain of carbons is

three long

propane

Branch is one long methyl

Methyl Propane


14/68

Practice

C

H

H

C

H

H

C

H

H C

H

H

H

C

H

H H

Methylbutane

H H H H H

C

H

C

H

CH C

H

C

H

H

C HH

C

H

HH

Ethylpentane


15/68

One More Practice

C C C

C

C

C C C

C

C

It doesnt matterwhich way you go!

(Provided you correctly pickthe longest unbranched chain)

MethylButane


16/68

Be Careful

H

C C C C CH H H H

H H H H

HH

CH H

CH

HH

Hexane

This is your

longest

uninterruptedchain

Methyl

Methyl Hexane


17/68

A Small Wrinkle

H

C C C C CH H H H

H H H H

HH

CH HH

H

C C C C CH H H H

H H H H

HH

CH HH

MethylPentane

MethylPentane

These are different molecules, though!!!


18/68

So Now What?

Since two different

molecules cant have

the same name, wemust differentiate

If we look closely,

though, the only

difference betweenthem is theposition of

the methyl group


19/68

Positioning

H

C C C C CH H H H

H H H H

HH

CH HH

H

C C C C CH H H H

H H H H

HH

CH HH

Here the methyl group

is on the second carbonfrom the end

Here the methyl group

is on the third carbonfrom the end

MethylPentane MethylPentane

So

2- 3-


20/68

Rules pt. 3

Identify the longest unbranchedchain ofcarbons

Name it as normal

Identify the branch

Name it but give it a yl suffix

Put the names of all branchesfirst, then put name of longest

chain Put the numberof the carbon the

branch is on (start numberingfrom the closest single end)


21/68

Practice

H

C C C C CH H H H

H HH H

HH

CH HH

CH

H

CH

H

H

C C C C CH H H H

H H H H

HH

CH H

H

C CH H

H H

CH

H

2-methyl heptane

4-methyl octane

H

C C C CH H H

H H H

H

CH H

H

CH

H

HCH

H 2-methyl hexane


22/68

Multiple Branches

So far weve only had

one branch

What happens whenthere are multple

branches?

Just add a prefix to

indicate the numberof

a particular type of

branch


23/68

Practice

H

C C C C C

H H H

H HH H

HH

CH HH

C

H

HC

H

H

CH H

H

heptane

methyl

methyl2-

2-

2-methyl, 2-methyl heptaneSounds redundant

2,2 dimethyl heptane


24/68

More Practice

CH HH

H

C C C C CH H H

H H H H

HH C CH H

HH

CH

H

CH H

H

C C C C CH H H

H H H

HH

CH HH

H

CH H

CH H

H

CH HH

2, 6-dimethyl

octane

3 ethyl-2,4-

dimethyl pentane


25/68

Is your arm sore yet?

Are you sick to death

of writing all those

carbons? Even worse, are you

sick of writing all

those Hydrogens?

How about this


26/68

Shorthand notation

C

H

H

C

H

H

C

H

H

C

H

H

H HKeep in mind that we have been

ignoring the hydrogens for a long

time.

Our names have been based

entirely on the positioning of the

carbons.

So lets now ignore the hydrogens

completely!


27/68

Is it that easy?

H

C C C C CH H H H

H HH H

HH

CH H

H

CH

H

CH

H

CH HH

H

C C C C CH H H

H H H H

HH C CH H

HH

CH

H

CH H

H


28/68

One More

C C C C C

H H H

H H H

HH

CH HH

H

CH H

CH H

H

CH HH

CH

H

Shorthand notation?

Name?

3-ethyl-2,4 dimethyl hexane


29/68

So is that it?

Not even close!!

There are literally

millions of differentorganic compounds.

What else can we do

to make things more

complicated?


30/68

Rings

Thus far we have dealt

with chains that are

straight or branched. If hydrocarbons are

long enough, one end

can wrap around and

link up with itself!

We call these cyclic

hydrocarbons.


31/68

Cyclic Hydrocarbons

Name the molecule as

normal

Add the prefix cyclo-to the front of the

name of the longest

chain

Start numbering from

the most important

branch in the ring


32/68

Examples

Cyclohexane

Cyclooctane


33/68

More Examples

Methyl cyclopentane

1,2 dimethyl

cyclohexane


34/68

Try These

1 ethyl, 3 methyl

cyclobutane

3 methyl, 1 propylcylclohexane


35/68

Multiple Bonds

So far, even with thecyclic structures wehave dealt only with

single bonds

Carbon can makemultiple bonds toanother carbon

This changes the name

Why?


36/68

Examine Structures

C

H

H

C

H

H

H H C2H6 Ethane- notice that eachcarbon has four bonds

What will happen to the structure if we double bond the two carbons?

C

H

C

H

H H

C2H4 Each carbon still has fourbonds BUT now the

hydrogens have changed!!


37/68

Naming molecules with multiple

bonds Name the molecule as

normal

Change the suffix of the

longest chain name

Double bonds = ene

Triple bonds = yne

Use numbering and

prefixes for positioning

and multiple multiple

bonds.


38/68

So.

C

H

H

C

H

H

H H C

H

C

H

H H C CH H

C2H6 C2H4 C2H2

ethane ethene ethyne


39/68

Practice

C C C CH H

H H H

H

H

CH H

H

CH

H 3 methyl-1-pentene

H

H

C C C C CH H H H

H H H

H CH

H

CH

H

2-heptene

H

H

C CH

H

H CH

CH

H

1-butene


40/68

How about in Shorthand?

Notice the twolines means the

double bond is

there!

2 pentene


41/68

Practice!

Methyl propene

2,4-dimethyl-2-pentene

3-ethyl-2,4,4-trimethyl-1-pentene


42/68

Tough Ones

2 methyl 1,3 butadiene

1,2dimethyl-1,4 cyclohexadiene


43/68

Triples?

3, 3-dimethyl-1-butyne

1,4 cyclohexadiyne


44/68

So thats it, right?

Not even close, bud.

All this.all this was

just for two elements,carbon and hydrogen!!

We havent even dealt

with any of the others,

yet.


45/68

Wait!! Dont jump!!

Get off that bridge.

Its not that bad

provided we arrangethings in an organized

fashion!


46/68

Functional Groups

Nature has done us afavor.

There are manycommon groups thatwe can organized orfile into differentcategories.

Then we can namethem based on thesecategories.


47/68

Functional Groups

A group of atoms that, when added to a

hydrocarbon chain, alter the chemical

properties of the chain. Just a few different functional groups to

know


48/68

Functional Groups

Halogens

Alcohols

Ethers Aldehydes

Ketones

Carboxylic Acids Esters

Amines

R-F, R-Cl, R-Br, R-I

R-OH

R-O-R R-COH

R-CO-R

R-COOH R-COO-R

R-NH2


49/68

Halides

Fluorides, Chlorides,

Bromides, and Iodides

Simply name themolecule as normal

but add the prefix

Fluoro, Chloro,

Bromo, or Iodo asnecessary


50/68

Halides

Cl

Cl

2, 3 dichlorohexane

I

I

3, 3 diiodo-1-pentene


51/68

Alcohols

R-OH

Name like normal

except add anolsuffix


52/68

AlcoholsOH

OHC

H

H

C

H

H

H

OH

2 propanol

ethanol

1cyclobutenol


53/68

Ethers

R-O-R

Name two R groups

withyl endings End name in ether


54/68

Ethers

ODimethyl ether

O Ethyl methyl ether


55/68

Aldehyde

R-COH

This is a carbon to

oxygen double bondwith a hydrogen at the

end.

Name as normal

except use a -alsuffix


56/68

Aldehydes

C

H

H

C

H

H

C

H

H

CH H

O

butanal

C

H

H

C

Cl

Cl

C

H

H

C H

O

C

H

H

H 3,3 dichloropentanal


57/68

Ketones

R-CO-R

This is a carbon to

oxygen double bondbut in the center of a

hydrocarbon chain

rather than the end

Name as normal butgive it a -one suffix


58/68

Ketones

propanone

2 hexanone

C

H

H

C

H

H

CH H

O

C

H

H

C

H

H

C

H

H

C

O

C

H

H

H C

H

H

H


59/68

Carboxylic Acids

R-COOH or R-CO2H

This is a carbon to

oxygn double bondwith the same carbon

single-bonded to an

OH group.

Name as normalexcept give it the

suffix -anoic acid.

H

C2H3O2


60/68

Carboxylic Acids

C

H

H

C

H

H

C

H

H

CH OH

O

Butanoic acid

C

H

H

C

H

H

FC

O

HO 3-Fluoropropanoic acid


61/68

Esters

R-COO-R

This is a carbon to oxygen

double bond with a carbon

to oxygen single bondedto another single bonded

carbon

Name by given secondary

branch -yl suffix andmain branch -anoate

suffix.


62/68

Esters

C

H

H

C

H

H

C

H

H

C

O

C

H

H

H C

H

H

HO

Secondary

BranchMain Branch

methylpentanoate

Methyl Pentanoate


63/68

Esters

C

H

H

H C

H

H

C

O

C

H

H

O C

H

H

HC

H

H

C

H

H

Butylpropanoate

C

H

H

H O

H

H

C

O

C

H

H

C C

H

H

HC

H

H

C

H

H

Methyl hexanoate


64/68

Amines

R-NH2

Name the R group

or groups with -ylendings

Add the word amine


65/68

Amines

C

H

H

N

H

H

H Methylamine

C

H

H

N

C

H

H

HH

H Dimethylamine


66/68

Summary

ClR

Halide

OHR

Alcohol

RR O

Ether

HR C

Aldehyde

O

RR C

Ketone

O

OHR CCarboxylic

Acid

O

OR CEster

O

R NH2R

Amine


67/68

Alkanes

Alkenes

Alkynes

Halides Alcohols

Ethers

Aldehydes

Ketones Carboxylic Acids

Esters

Amines

Summary

- -ane

= -ene

-yne

R-X -o R-OH -ol

R-O-R -yl ether

R-COH -al

R-CO-R -one R-COOH -anoic acid

R-COO-R -yl -anoate

R-NH2 -yl amine


68/68

Can You Do This?

YES!

It takes:

Memorization

Practice

Practice

Practice

Practice And, oh yes

Practice!

Organic Naming Rules 2

Documents