Download Organic Naming Rules

Organic Chemistry
CHS Chemistry
What is organic chemistry? (You can
use your book!)
Agenda
• Review Acid/Base Equilibrium
• Start Organic Chemistry!
Organic Compounds
• Consist of mainly four elements
Carbon
Hydrogen
Oxygen
Nitrogen
Organic: molecules that come from “only” living things
Naming organic molecules: Why Do We
Need a Separate Set of Rules?
Examine some typical organic compounds
• CH4 Carbon tetrahydride
• C2H6 Dicarbon hexahydride
Name these using typical covalent rules
So?
How about these:
• C4H10 Tetracarbon decahydride
• C5H12 Pentacarbon ??? hydride
Isomers
Give the formula for the following
H
H H H H
H C C C C H
H H H H
Different
Structure
H C H
H
H
H C C C H
H H H
C4H10
Same name
and formula
C4H10
Overall Problems
• Memorizing too many prefixes for large numbers
• Different structures having the same formulas
• Keep in mind that thus far we’ve only dealt with
TWO different elements! (What if a chemical is the
same structure, but has the OH moved from one C
to another? It’s not the same molecule anymore!)
So what to do?
Hydrogens will always surround the carbons
regardless of shape
H H H H H
H C C C C C H
H H H H H
C5H12
H
H C H
H H
H
H C C C C H
H H
H H
H
H C H
H
H
H C C C H
H
H
H C H
H
C5H12
C5H12
Solution
Since number of hydrogens are just always surrounding the carbons,
why don’t we ignore them?
Name the molecule simply based on number AND the arrangement
of CARBONS
We can always add prefixes or suffixes later for telling where there
are “side branches”
Organic Nomenclature
• There are three parts to a compound name:
• Base: This tells how many carbons are in the longest
continuous chain.
© 2009, Prentice-Hall, Inc.
Organic Nomenclature
• There are three parts to a compound name:
• Base: This tells how many carbons are in the longest
continuous chain.
• Suffix: This tells what family of compound it is.
© 2009, Prentice-Hall, Inc.
Organic Nomenclature
• There are three parts to a compound name:
• Base: This tells how many carbons are in the longest
continuous chain.
• Suffix: This tells what type of compound it is.
• Prefix: This tells what/how many branches are attached
to the chain.
© 2009, Prentice-Hall, Inc.
Suffixes
• Suffixes on the end of the name of an
organic molecule tell you what major family
the molecule belongs to
• The suffix for an alkane (a molecule with all
single bonds and only C and H) is “-ane”
The Base
• The “base” part of the name tells you how
many carbons are in the main chain of the
molecule
• The main chain of the molecule is defined
for alkanes as being the longest chain in the
molecule
Base and suffix…
• The base is named based on the number of
carbons
• 1 carbon = “meth”
• So a one-carbon alkane is called methane
CH4
Base and suffix…
• 2 carbons = “eth”
• So a two carbon alkane is called ethane.
CH3CH3
Base and suffix…
• 3 carbons = “prop”
• So a three carbon alkane is called propane.
CH3CH2CH3
Base and suffix…
• 4 carbons = “but”
• So a four carbon alkane is called butane.
CH3CH2CH2CH3
And now the rest…
• 5 carbons = “pent”
• 6 carbons = “hex”
• 7 carbons = “hept”
• 8 carbons = “oct”
• 9 carbons = “non”
• 10 carbons = “dec”
Mnemonic for First Four Prefixes
First four prefixes
• Meth• Eth• Prop• But-
Monkeys
Eat
Peeled
Bananas
Did that Really Help?
H
H C H
H
H H
H C C H
H H
CH4
Carbon tetrahydride becomes: Methane
C 2 H6
Dicarbon hexahydride becomes: Ethane
H H H H H H H H
H C C C C C C C C H
H H H H H H H H
C8H18
Octacarbon ???hydride becomes:
Octane
Branches
• Straight-chain alkanes (Just C & H with single bonds) are
now easy
H H H H
H C C C C H
C4H10 Butane
H H H H
But how do we deal with branches?
H
H C H
H
H
H C C C H
H H H
C4H10 ????
Bell Ringer
Name the bases for carbon chains 1-10 long
Rules Part 2: Prefixes
•
•
•
•
•
Identify the longest unbranched chain of carbons
Name it as normal
Identify the branch
Name the branch but give it a “–yl” suffix
Put the names of all branches in alphabetical order in
front of the name for the longest carbon chain
Prefixes
• The most common prefixes we have in organic molecules
are those little fragments of carbon pieces attached to the
main chains.
The carbon fragments are called “alkyl groups”. They all end
in “-yl” to indicate they are fragments of a bigger molecule.
… but there are other types of fragments out there!
(to be continued…)
Example
methyl
Branch is one long
H
Longest unbranched
chain of carbons is
three long
H C H
H
H
H C C C H
propane
H H H
Methyl Propane
Practice
H H H H
H C C C C H
Methyl butane
H H
H
H C H
H
H H H H H
H C C C C C H
H H
H H
H C H
H C H
H
Ethyl pentane
One More Practice
C C C
C
C
C C C
C
C
Methyl Butane
It doesn’t matter
which way you go!
(Provided you correctly pick
the longest unbranched chain)
Be Careful
H
H
H
H
H
H
C C C C C
H
H
H
H
H
H
H
C
C
H
H
H
This is your
longest
uninterrupted
chain
Methyl
Hexane
Methyl Hexane
A Small Wrinkle
H
H
H
H
H
H
C C C C C
H
H
H
H
Methyl Pentane
H
Methyl Pentane
H
H
C
H
H
H
H
H
H
H
H
C C C C C
H
H
H
H
C
H
H
H
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
2- Methyl Pentane
H
H
H
H
H
H
C C C C C
H
H
3- Methyl Pentane
H
H
H
H
H
H
C
H
H
H
H
C C C C C
H
H
H
H
H
H
C
H
H
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
So…
Rules Part 3: Prefixes
•
•
•
•
•
Identify the longest unbranched chain of carbons
Name it as normal
Identify the branch
Name the branch but give it a “–yl” suffix
Put the names of all branches in alphabetical order in front
of the name for the longest carbon chain
• Put the number of the carbon the branch is on (start
numbering from the closest end)
Practice
H
H
H
H
H
H
H
H
C C C C C C C
H
H
H
C
H
H
H
2-methyl heptane
H
H
H
H
H
H
H
H
H
H
H
H
H
C C C C C C C C
H
H
H
H
H
C
H
H
H
H
4-methyl octane
H
H
H
H
H
H
H
H
H
C C C C C C
H
H
H
H
H
H
C
H
H
H
2-methyl hexane
Multiple Branches
• So far we’ve only had
one branch
• What happens when
there are multiple
branches?
• Add a prefix to indicate
the number of a
particular type of
branch
Practice
2- methyl
H
H
C
H
H
H
H
H
H
H
H
C C C C C C C
H
H
H
C
H
H
H
H
H
heptane
H
H
2- methyl
2-methyl, 2-methyl heptane Sounds redundant
2,2 dimethyl heptane
More Practice
H
H
H
H
C
H
H
H
H
H
H
H
C C C C C C C C
H
H
H
H
H
H
H
2, 6-dimethyl octane
H
H
C
H
H
H
H
H
H
H
C
C
H
3 ethyl-2,4-dimethyl pentane
H
H
H
H
C C C C C
H
H
H
C
H
H
H
H
C
H
H
H
Name the following
H
H
H
H
H
C
C
H
3 ethyl-2,4-dimethyl pentane
H
H
H
H
C C C C C
H
H
H
C
H
H
H
H
C
H
H
H
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…
Bell Ringer
• Draw the complete and then the skeletal
structure of 2-methyl-hexane
Shorthand notation
H H H H
H C C C C H
H H H H
Keep 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
H
H
H
H
H
H
C C C C C C C
H
H
H
C
H
H
H
H
H
H
H
H
H
H
H
H
C
H
H
H
H
H
H
H
C C C C C C C C
H
H
H
H
H
H
H
H
C
H
H
H
Give the formula for…
One More
H
H
H
H
H
C
C
H
Skeletal notation?
H
H
H
H
H
C C C C C C
H
H
H
C
H
H
H
H
C
H
H
H
H
3-ethyl 2,4-dimethyl hexane
Name?
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” (longest) branch in the ring
Cyclic Compounds
• Word of caution: don’t double dip… its
really easy to double count the carbon (*)
that the alkyl group is attached to.
• Alkyl groups are only those BEYOND the
ring carbons. Thus, this is a propyl group
not a butyl group.
*
1
3
2
Cyclic Compounds – Multiple
Groups
• When a ring has multiple groups, the rule for
numbering is: “Number around the ring so as
to arrive at the lowest possible sum of the
position numbers”.
• The sum in this molecule is 1 + 3 = 4.
1
3
Cyclic Compounds – Multiple
Groups
• Lowest possible sum?
4
1
•1+2+4=7
2
Examples
Cyclohexane
Cyclooctane
More Examples
Methyl cyclopentane
1,2-dimethyl
cyclohexane
Try These
1-ethyl 3-methyl cyclobutane
3-methyl 1-propyl cylclohexane
Can You Do This?
•
•
•
•
•
•
•
•
•
YES!
It takes:
Memorization
Practice
Practice
Practice
Practice
And, oh yes…
Practice!
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? They’re in a different family!
Examine Structures
H H
H C C H
C2H6
Ethane- notice that each
carbon has four bonds
H H
What will happen to the structure if we double bond the two carbons?
H H
H C C H
C2H4
Each carbon still has four
bonds BUT now the
hydrogens have changed!!
Naming molecules with multiple
bonds
•
•
•
•
•
Name the molecule as normal
Change the suffix of the longest chain name
Double bonds = ene (Alkene family)
Triple bonds = yne (alkyne family)
Use numbering and prefixes for positioning and multiple
multiple bonds.
So….
H H
H H
H C C H
H C C H
H C C H
C2H6
C2H4
C2H2
ethane
ethene
ethyne
H H
Name the following:
H
H
H
H
H
H
H
C C C C C C C
H
H
H
H
H
H
H
H
2-heptene
H
H
C C C C
H
H
H
1-butene
H
H
H
H
H
H
C
H
H
H
H
C C C C C
H
H
H
H
3-methyl 1-pentene
How about in Shorthand?
2-pentene
Notice the two lines
means the double bond is
there!
Practice!
2-methyl propene
2,4-dimethyl 2-pentene
3-ethyl 2,4,4-trimethyl 1-pentene
Bell Ringer: Name the following
2-methyl 1,3-butadiene
1,2-dimethyl1,4-cyclohexadiene
Triples?
3, 3-dimethyl1-butyne
1,4-cyclohexadiyne
Cis and Trans
Cis and Trans tell you which way the carbon chain comes
off of the double bonds
Cis and Trans
Cis and Trans tell you which way the carbon chain comes
off of the double bonds (use the longest chain)
trans-2-butene
cis-2-butene
trans-3-methyl hex-3-ene
cis-3-methyl 3-hexene
Functional Groups (Families)
• 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
• 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
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
2, 3-dichlorohexane
Cl
I
3, 3-diiodo-1-pentene
I
Alcohols
• R-OH
• Name like normal except add an –ol suffix (use
a number to denote where the alcohol is)
Alcohols
OH
OH
2-propanol
H H
H C C OH
H H
ethanol
1-cyclobutenol
Ethers
• R-O-R
• Name two “R” groups with –yl endings
• End name in “ether”
Ethers
O
O
Dimethyl ether
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
Aldehydes
H H H O
H C C C C H
butanal
H H H
H H Cl H O
H C C C C C H
H H Cl H
3,3-dichloropentanal
Ketones
• 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
Ketones
H O H
propanone
H C C C H
H
H
H H H H O H
H C C C C C C H
H H H H
H
2-hexanone
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”.
Carboxylic Acids
H H H O
H C C C C OH
butanoic acid
H H H
O H H
HO C C C F
H H
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
Secondary
Branch
Main Branch
H H H H O
H
H C C C C C O C H
H H H H
H
methyl
pentanoate
Methyl Pentanoate
Esters
H H O
H H H H
H C C C O C C C C H
H H
H
H H H H
O H
H H H H
H C O C C C C C C H
H
Butyl propanoate
H
H H H H
Methyl hexanoate
Amines
• R-NH2
• Name the “R” group or
groups with “-yl”
endings
• Add the word “amine”
Amines
H
H
Methyl amine
H C N
H
H
H
H
H C N
C
H
H
H
H
Dimethyl amine
Summary
R Cl
Halide
R OH
Alcohol
O
O
R C H
Aldehyde
R C R
Ketone
R O R
Ether
O
R C OH
Carboxylic
Acid
O
R C O R
Ester
R NH2
Amine
Summary
• Alkanes
• Alkenes
• Alkynes
• Halides (halogens)
• Alcohols
• Ethers
• Aldehydes
• Ketones
• Carboxylic Acids
• Esters
• Amines
=
R-X
R-OH
R-O-R
R-COH
R-CO-R
R-COOH
R-COO-R
R-NH2
“-ane”
“-ene”
“-yne”
“-(halogenroot)o”
“-ol”
“-yl ether”
“-al”
“-one”
“-anoic acid”
“-yl” “-anoate”
“-yl amine”
Other common alkyl side chains
iso-propyl
tert-butyl
iso-butyl
iso-pentyl
sec-butyl
sec-pentyl
5-sec-butyl-4-isopropylnonane
6-tert-butyl-3-methyldecane
Aromatic Rings: The last family!
Benzene becomes the base name
Name the rest like normal! 
Benzene
Chlorobenzene
2-chloro-1methylbenzene
methylbenzene
Benzoic acid
Bell Question: What is the general formula for a carboxylic acid?
• Homework questions? Please have it out
• In class functional group chart lab:
table of functional group, name, prefix/suffix, structure, example :
must complete on own time (may use on quest tomorrow)
• Today: Review for organic naming
Ortho, Meta, Para
3-bromo-14-bromo-1- methylbenzene 2-bromo-1methylbenzene
methylbenzene
Homework:
• Finish WS
• 24:33, 37, 43, 47, 49