Organic Naming Rules Chem 332 For complete Rules go to:

Organic Naming Rules

Chem 332

For complete Rules go to:

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

Organic Compounds

• Consist of mainly four elements

• Carbon

• Hydrogen

• Oxygen

• Nitrogen

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

So?

• How about these:• C4H10

• C5H12

• See my point?

Tetracarbon decahydride

Pentacarbon ??? hydride

Isomers• If that’s not enough, how about this one:

C

H

H

C

H

H

C

H

H

C

H

H

H H

Formula?

C4H10

C

H

H

C

H

HC

H

HCH

H

H

H

Formula?

C4H10

Different Structure

Same Formula

Overall Problems

• Memorizing too many prefixes for large numbers

• Different chemicals having the same formulas

• Keep in mind that thus far we’ve only dealt with TWO different elements!

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

C

H

H

C5H12C5H12

C5H12

Solution

• Since number of hydrogens don’t 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

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

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:

OctaneC8H18

Alkanes• Alkanes are hydrocarbons

that contain only single bonds.

• The general formula for alkanes is: CnH2n+2

• n represents the number of carbon atoms in the molecule

Some Practice

• What is the formula for an alkane that has 6 carbon atoms?

• Use the general formula to figure this out.• Draw out the dot structure for this

molecule.• Do all carbon atoms share 4 times?• Do all hydrogen atoms share 1 time?

Hmm, not too bad!If there are 6 carbon atoms,

then the H atoms must equal 14

Formula = C6H14 Hexane

Dot Structure

C – C – C – C – C – C

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

HC

H

HC

H

HCH

H

H

H

C4H10 ????

Rules pt. 2

• Identify the longest unbranched chain of carbons

• Name it as normal• Identify the branch

• Name it but give it a “–yl” suffix• Put the names of all branches

first, then put name of longest chain

Example

C

H

HC

H

HC

H

HCH

H

H

HLongest unbranched chain of carbons is

three long

propane

Branch is one long methyl

Methyl Propane

Practice

C

H

H

C

H

H

C

H

H C

H

H

H

C

H

H H

Methyl butane

H H H H H

C

H

C

H

CH C

H

C

H

H

C HH

C

H

HH

Ethyl pentane

One More Practice

C C C

C

C

C C C

C

C

It doesn’t matter which way you go!(Provided you correctly pick the longest unbranched chain)

Methyl Butane

Be CarefulH

C C C C CH H H H

H H H H

HH

CH H

CH

HH

HexaneThis is your longest uninterrupted chain

Methyl

Methyl Hexane

A Small Wrinkle

H

C C C C CH H H H

H H H H

HH

CH H

H

H

C C C C CH H H H

H H H H

HH

CH H

H

Methyl Pentane

Methyl Pentane

These are different molecules, though!!!

So Now What?

• Since two different molecules can’t have the same name, we must differentiate

• If we look closely, though, the only difference between them is the position of the methyl group

Positioning

H

C C C C CH H H H

H H H H

HH

CH H

H

H

C C C C CH H H H

H H H H

HH

CH H

H

Here the methyl group is on the second carbon from the end

Here the methyl group is on the third carbon from the end

Methyl Pentane Methyl Pentane

So…

2- 3-

Rules pt. 3

• Identify the longest unbranched chain of carbons

• Name it as normal• Identify the branch

• Name it but give it a “–yl” suffix• Put the names of all branches

first, then put name of longest chain

• Put the number of the carbon the branch is on (start numbering

from the closest single end)

Practice

H

C C C C CH H H H

H HH H

HH

CH H

H

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

Multiple Branches

• So far we’ve only had one branch

• What happens when there are multple branches?

• Just add a prefix to indicate the number of a particular type of branch

Practice

H

C C C C CH H H

H HH H

HH

CH H

H

CH

H

CH

H

CH H

H

heptane

methyl

methyl2-

2-

2-methyl, 2-methyl heptaneSounds redundant

2,2 dimethyl heptane

More Practice

CH H

H

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 H

H

H

CH H

CH H

H

CH H

H

2, 6-dimethyl octane

3 ethyl-2,4-dimethyl pentane

Multiple Bonds

• So far, even with the cyclic structures we have dealt only with single bonds

• Carbon can make multiple bonds to another carbon

• This changes the name

• Why?

Examine Structures

C

H

H

C

H

H

H H C2H6Ethane- notice that each carbon has four bonds

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

C

H

C

H

H HC2H4

Each carbon still has four bonds BUT now the hydrogens have changed!!

Alkenes

• Alkenes contain a double bond in the molecule.

• The general formula for alkenes is CnH2n

A little practiceA little practice..

• What is the formula for an alkene with 4 carbons?

• Draw the dot structure.• You can place the double bond between any

two carbons since it wasn’t specified.

Wow, I can do this!Wow, I can do this!

• The formula is C4H8 Butene

• The dot structure is

C – C = C – C

Alkynes

• Alkynes contain a triple bond in the molecule.

• The general formula for alkynes is CnH2n-2

Some more practice.

• What is the formula for an alkyne with 7 carbons?

• Draw the dot structure.• You can place the triple bond between any

two carbons since it wasn’t specified.

I am so smart!

• The formula is C7H12 Heptyne

• The dot structure is

C – C ≡ C – C – C – C – C

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.

So….

C

H

H

C

H

H

H H C

H

C

H

H H C CH H

C2H6 C2H4 C2H2

ethane ethene ethyne

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

1-

2-

3-

4-

5-

6-

7-

8-

9-

10-

Mono

Di

Tri

Tetra

Penta

Hexa

Hepta

Octa

Nona

Deca

Prefixes for #’s of groups

1-

2-

3-

4-

5-

6-

7-

8-

9-

10-

Meth

Eth

Prop

But

Penta

Hexa

Hepta

Octa

Nona

Deca

Prefixes for #’s of CARBONS

Suffixes Single

Double

Triple

-ane

-ene

-yne

Circles use Cyclo-

1. Identify the longest chain (it must contain the double or triple bond if present)

2. Name it as normal

3. If Double or triple bonds are present use the correct suffix and identify the starting position with a number

4. Identify the branches

5. Name any branches by using carbon prefixes and –yl suffixes and identify their positions with a number

6. Add a prefix to indicate multiple branches using the groups prefixes

Branches use -yl

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…

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!

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 H

H

H

C C C C CH H H

H H H H

HH C CH H

HH

CH

H

CH H

H

One More

C C C C CH H H

H H H

HH

CH H

H

H

CH H

CH H

H

CH H

H

CH

H

Shorthand notation?

Name?

3-ethyl-2,4 dimethyl hexane

So is that it?

• Not even close!!• There are literally millions of different

organic compounds.• What else can we do

to make things more complicated?

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.

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

Examples

Cyclohexane

Cyclooctane

More Examples

Methyl cyclopentane

1,2 dimethyl cyclohexane

Try These

1 ethyl, 3 methyl cyclobutane

1 propyl, 3 methyl cylclohexane

How about in Shorthand?

Notice the two lines means the double bond is there!

2 pentene

Practice!

Methyl propene

2,4-dimethyl-2-pentene

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

AP Area

• Unless you are a chemist, or in AP Chem you don’t need to worry about this

Tough Ones

2 methyl 1,3 butadiene

1,2 dimethyl-1,4 cyclohexadiene

Triples?

3, 3-dimethyl-1-butyne

1,4 cyclohexadiyne

So that’s it, right?

• Not even close, bud.• All this….all this was

just for two elements, carbon and hydrogen!!

• We haven’t even dealt with any of the others, yet.

Wait!! Don’t jump!!

• Get off that bridge.• It’s not that bad

provided we arrange things in an organized fashion!

Functional Groups

• Nature has done us a favor.

• There are many common groups that we can organized or file into different categories.

• Then we can name them based on these categories.

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…

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

Functional Groups

• Nature has done us a favor.

• There are many common groups that we can organize or file into different categories.

• Then we can name them based on these categories.

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…

Functional Groups

• Halogens• Alcohols• Ethers

• Aldehydes• Ketones

• Carboxylic Acids• Esters• Amines

• R-F, R-Cl, R-Br, • R-OH• R-O-R• R-COH• R-CO-R• R-COOH• R-COO-R• R-NH2

What the heck is R?

• The R represents a chain of carbon atoms.

• The the length of the chain is not significant.

• It is important to understand where the functional group lies in relation to the chain of carbon atoms

Halides

• Fluorides, Chlorides, Bromides, and Iodides

• Simply name the molecule as normal but add the prefix Fluoro, Chloro, Bromo, or Iodo as necessary

Halides

Cl

Cl

2, 3 dichlorohexane

I

I

3, 3 diiodo-1-pentene

Alcohols

• R-OH• Name like normal

except add an –ol suffix

Alcohols

OH

OHC

H

H

C

H

H

H

OH

2 propanol

ethanol

1butenol

Ethers

• R-O-R• Name two “R” groups

with –yl endings• End name in ether

Uses of Ethers

Common solvents.

General anesthetic

Ethers are slightly soluble in water.

Ethers

ODimethyl ether

O Ethyl methyl ether

Aldehyde

• R-COH• This is a carbon to

oxygen double bond with a hydrogen at the end.

• Name as normal except use a “-al” suffix

Al Who?Al Who?

Aldehydes

C

H

H

C

H

H

C

H

H

CH H

Obutanal

C

H

H

C

Cl

Cl

C

H

H

C H

O

C

H

H

H 3,3 dichloropentanal

Uses ofUses of AldehydesAldehydes• Formaldehyde H2CO is used in the production of:

Dollar BillsInk used in books, magazines, and newspapersWrinkle-Free ClothingGluesCar bumpers

KetonesKetones

• R-CO-R• This is a carbon to

oxygen double bond but in the center of a hydrocarbon chain rather than the end

• Name as normal but give it a “-one” suffix

Uses of KetonesUses of Ketones

• Ketones are often used as stabilizers in paints and perfumes. They prevent the other chemicals from degrading or breaking down.

• Acetone is found in nail polish remover.

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

Carboxylic Acids

• R-COOH or R-CO2H

• This is a carbon to oxygn double bond with the same carbon single-bonded to an OH group.

• Name as normal except give it the suffix “-anoic acid”.

HC

2 H3 O

2

Uses of Carboxylic AcidsUses of Carboxylic Acids

Carboxylic Acids are relatively weak acids.

Acetic Acid is the main ingredient in vinegar

Carboxylic Acids

C

H

H

C

H

H

C

H

H

CH OH

O

Butananoic acid

C

H

H

C

H

H

FC

O

HO 3-Fluoropropanoic acid

Esters

• R-COO-R• This is a carbon to oxygen

double bond with a carbon to oxygen single bonded to another single bonded carbon

• Name by given secondary branch “-yl” suffix and main branch “-anoate” suffix.

Esters

C

H

H

C

H

H

C

H

H

C

O

C

H

H

H C

H

H

HO

Secondary Branch

Main Branch

methylpentanoate

Methyl Pentanoate

Esters

C

H

H

H C

H

H

C

O

C

H

H

O C

H

H

HC

H

H

C

H

H

Butyl propanoate

C

H

H

H O

H

H

C

O

C

H

H

C C

H

H

HC

H

H

C

H

H

Methyl hexanoate

AminesAmines

• R-NH2

• Name the “R” group or groups with “-yl” endings

• Add the word “amine”

Amines

C

H

H

N

H

H

H Methyl amine

C

H

H

N

C

H

H

HH

H Dimethyl amine

Summary

ClR

Halide

OHRAlcohol

RR OEther

HR CAldehyde

O

RR CKetone

O

OHR CCarboxylic

Acid

O

OR CEster

O

R NH2RAmine

• 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”