Transcript Naming Organic Compounds

Introduction to Organic
Chemistry
Beginning the story of carbon
Petroleum – the Primary Source
Hydrocarbons - Compounds
containing only carbon and
hydrogen
• “Saturated” hydrocarbons are
called alkanes
– As many hydrogens in the
molecule as possible
CH4
Methane
Major Sources of Methane
• Rice Paddies
• Cattle
• Decaying Garbage
• Natural Gas
–B. P. – 161.5
C2H6
CH3CH3
Ethane
Ethane Facts
• Component of natural gas
– B. P. – 88.6
C3H8
CH3CH2CH3
Propane
Commercial Uses
• LP (liquid petroleum) Gas
–Home heating
–Cooking
–Recreational Uses
• Outdoor grills
• Gas Fireplaces
–B. P. - 42
C4H10
CH3 CH2CH2CH3
CH3(CH2)2CH3
Butane
Butane facts
• Easily liquefied, vaporized
at room temp
–B. P. -0.5
• Pocket lighters
• Portable, rechargeable
torches
The rest of the family of alkanes
• General Formula: CnH2n+2
• Prefixes:
–1
–2
–3
–4
–5
Meth
Eth
Prop
But
Pent
6
7
8
9
10
Hex
Hept
Oct
Non
Dec
Ways to show Molecules
• Molecular formula:
C2H6
– Shows only the number of each element
• Lewis Dot Structure
– Shows structure and ALL valence electrons
– Must have one dot for each electron
HH
.. ..
H:C:C:H
.. ..
H H
More ways to show molecules
• Condensed structural formula
– Shows or specifically indicates the location of
each element
CH3CH3
- Bonds are implied, not shown
Still more ways….
• Extended Structural formula
– Hybrid of condensed structural and Lewis dot
– Replaces pair of electrons with a solid line
– Chemists sometimes mix condensed and extended
structural formulas, showing some but not all bonds
HH
| |
H-C-C-H
CH3 – CH3
| |
H H
Isomers:
• Same molecular formula,
different structure and
properties
Butane: First Hydrocarbon with
Isomers
CH3CH2CH2CH3
or
CH3 CH CH3
CH3
Groups as Substituents
•
•
•
•
•
•
Methane
Ethane
Propane
Butane
Pentane
Etc.
becomes
becomes
becomes
becomes
becomes
methyl
ethyl
propyl
butyl
pentyl
• The generalized substituent: R- = any alkyl
group
Numbers of Isomers
•
•
•
•
•
•
•
4 carbons – 2
5 carbons – 3
6 carbons – 5
7 carbons – 9
8 carbons – 18
9 carbons – 35
10 carbons - 75
Naming Isomers
CH3-CH2-CH2-CH3
1-butane
The 1 makes clear that all the carbons
are in a line
CH3 – CH – CH3 2-methyl propane
|
CH3
Note: Carbon’s Four Bonds!
H
|
CH3 – C – CH3
|
CH3
vs.
CH3-CH2-CH2-CH3
On the second carbon in the row, we removed
an H, so we could hook on a C and still have 4
and only 4 bonds on each C
Systematic names
• Developed by IUPAC (International Union
of Pure and Applied Chemistry)
– Identify and name the longest carbon chain
– Number it from one end to the other so that
groups attached will have the lowest numbers
possible
Example
1
2 3 4 5
6
CH3 CH CH2 CH2 CH2 CH3
|
CH3
2-methylhexane, not 5-methylhexane
More Complex
1
2 3 4
5
6
7
CH3 CH CH CH2 CH2 CH2 CH3
| |
CH3 CH3
2,3-dimethylheptane
• As we learn “functional groups” (the
general name for other atoms or groups
we can hook onto carbon), we will practice
additional names.
Other Hydrocarbon Families
• Saturated hydrocarbons = “Alkanes”
• Other types of hydrocarbons also group in
families
• Basically, the prefix of the compound tells
the number of carbons, always
• The ending of the name tells about the
bonding
• This makes learning all of them EASY!
Unsaturated Compounds: Alkenes
• Two or more carbons
• At least one double bond
– May be located anywhere in the chain of
carbon atoms
C2H4
CH2=CH2
Ethene (also called
ethylene)
C3H6
CH2=CH-CH3
Propene (or
propylene)
C4H8
Multiple Isomers:
CH2=CH-CH2-CH3 or
CH3-CH=CH-CH3 which can be
CH3
CH3
C=C
H
CH3
or
H
C=C
H
or
CH3
C=CH2
CH3
H
CH3
Butene Isomer Names
• n-butene or 1-butene
• 2 – butene
– Cis (methyls on same side)
– Trans (methyls on opposite sides)
• Cis and trans are geometric isomers
– iso-butene or methyl propene
• Vs. 1 and 2 butene, structural isomers
General formula for alkenes
Cn H2n
Then there’s the triple bond:
Alkynes
• C2H2
• HC CH
• Ethyne, also called acetylene
General formula for Alkynes:
CnH2n-2
Isomers of Alkynes
• Positional or structural isomers only
(location along chain, branching)
– Because, alkynes are linear
Cycloalkanes
Cyclopropane
CH2 – CH2
CH2
Cyclobutane
CH2 – CH2
CH2 – CH2
And more…..
Cyclopentane
CH2 – CH2
CH2
CH2
CH2
Cyclohexane
CH2
CH2
CH2
CH2
CH2
CH2
“Boat”
CH2
CH2
CH2
CH2
CH2
CH2
“Chair”
One more way to illustrate:
• Hydrocarbon frameworks can be
illustrated by bent lines, each bend being a
carbon and its associated hydrogens:
= pentane
= cyclopropane
Aromatics- cyclics with double
bonds
Benzene – Kekule’s dream
CH
CH
CH
CH

CH
CH
CH
CH
CH
CH
CH
CH
As a substituent, abbreviated Ar for “Aryl”
Cyclic Aromatics
• All Bond lengths are equal
• Do not easily undergo addition reactions
• “Compromise” structure:
CH
CH
CH
CH
CH
CH
Adding Functional Groups
• Halogens
– Substitution for hydrogen with alkanes,
aromatics
RCH3 + Cl2 
ArH + Cl2 
RCH2Cl + HCl
ArCl + HCl
– Addition to double bonds
RCH=CHR + Cl2  RCHCl-CHClR
Compounds with Oxygen
• Alcohols: R – OH
– Addition of water across a double bond or
replacement of a halogen
• Aldehydes: C=O at the end of a molecule
R – C=OH
• Ketones: C=O in the middle of a molecule
R – C=O – R
More Oxygen Compounds
• Organic Acids: C=O-OH
– The H is capable of ionizing to give
R – C=O – O - and H+
• Esters: combine an acid and an alcohol:
R – C=O – O – R
• Ethers: use a singly-bound oxygen to join
two alkyl groups:
R–O-R
Versatile nitrogen: Amines
• A –NH2 group can substitute for a
halogen:
R – CH2 – NH2
• But also, nitrogen can have one, two, or
three alkyl groups hooked to it:
– R – NH2
– R2 – NH
– R3 – N
primary amine (1o)
secondary amine (2o)
tertiary amine (3o)
Amides: Acids plus amines
• As long as an amine has at least one
hydrogen on nitrogen, it can react with an
organic acid to produce an amide and
water
R – C=O-OH + R’NH2  RC=ONHR’ +
H2O
Esters: Acids plus alcohols
• Similar reaction to Amides:
RCOOH + R’OH  RCOOR’ + H2O
Amino Acids: Building blocks of us
• Amino Acids have both an amino group
(NH2) and an acid group (COOH).
CH3 –CH – COOH
|
NH2
• Amino Acids link together to make up
proteins in the body
Basic Organic Reactions
• Addition to an olefin (alkene)
• CH2=CH2 + HCl  CH3-CH2Cl
– Hydrohalogenation
• CH2=CH2 + Br2  CH2Br-CH2Br
– Halogen addition
• CH2=CH2 + H2  CH3 – CH3
– Reduction
Basic Organic Reactions, con’t
•
•
•
•
Replacement/substitution
CH3-CH2Cl + KOH  CH3-CH2OH + KCl
CH3-CH2OH + HCl  CH3-CH2Cl + H2O
CH3CH3 + Cl2  CH3CH2Cl + HCl
• Dehydration
• CH3-CH2OH  CH2=CH2 + H2O
Basic Organic Reactions, con’t
• Esterification
• CH3COOH + CH3OH  CH3COOCH3 +
H2O
• Amidation
• CH3COOH + CH3NH2  CH3CONHCH3 +
H2O
Polymers: Our Plastic World
• Addition polymers: link together by
combining double-bonded materials
– Ethylene CH2=CH2  Polyethylene
– Propylene CH2=CH  Polypropylene
|
CH3
More addition polymers
Styrene CH2=CH  polystyrene
|
Vinyl Chloride CH2=CHCl - PVC
And then Condensation Polymers
• Polyester (like Dacron®)
HOOC
COOH + HOCH2CH2OH
• Polyamide (like nylon)
H2N (CH2)6 NH2 + HOOC (CH2)4COOH
or H2N (CH2)5 COOH