Organic Chemistry
Organic Chemistry: The chemistry of carbon
and carbon-based compounds
Organic Chemistry in everyday life:
Smells & tastes: fruits, chocolate, fish, mint
Medications: Aspirin, Tylenol, Decongestants, Sedatives
Addictive substances: Caffeine, Nicotine, Alcohol,
Narcotics
Hormones/Neurotransmitters: Adrenaline, Epinephrine
Food/Nutrients: Carbohydrates, Protein, Fat, Vitamins
Genetics: DNA, RNA
Consumer products: Plastics, Nylon, Rayon, Polyester
Drawing Organic Structures
Butane: C4H10
C C C C
H
H
H
H
H
H
H
H
H
H
CH3 CH2 CH2 CH3
CH3CH2CH2CH3
CH3(CH2)2CH3
Shortcuts make structures easier & faster to draw
Line Structure
• Only shows bonds
• C atoms assumed at each end
and intersection of bonds
• H atoms not shown
• Assume 4 bonds to each C
• Fulfill C’s 4 bonds by adding H’s
Lewis Structure
Condensed Structures
Carbon Atoms
Types of Organic Compounds Classified according to functional group
Alkane
Alkene
Alkyne
Haloalkane
Alcohol
Ether
Ketone
Aldehyde
Carboxylic acid
Amine
Amino acid
Amide
O
H
O
NH2
O
OH
O
H2NOH
O
OH
Cl
Br
NH2
C C
O
Big Idea in Organic Chemistry
Structure controls Function
Each functional group has predictable reactivity
Alkanes or Paraffins • All C atoms are tetrahedral and sp3 hybridized (only C-C
single bonds)
• General formula = CnH2n+2 (CH4, C2H6, C3H8, C4H10, etc.)
• Can have linear or branched alkanes
C5H12
• Same molecular formula, different structure: structural isomers
• Branches are called substituents
• Primary (1°) carbon atom: bound to one other C atom
• Secondary (2°) C atom: bound to 2 other C atoms
• Tertiary (3°) C atom: ” 3 ”
• Quaternary (4°) C atom: ” 4 ”
C CH2H3C
H
CH3
CH33° 1°
2°
Names of Linear Alkanes and Alkyl Substituents
Alkane Alkyl substituents # of
C atoms
CH4
CH3CH3
CH3CH2CH3
CH3CH2CH2CH3
-CH3
-CH2CH3
-CH2CH2CH3
Methyl
Ethyl
Propyl
etc.
Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane
Octane
Nonane
Decane
Root: number of C atoms
Suffix: functional group
(-ane for alkanes)
(-yl for alkyl groups)
1
2
3
4
5
6
7
8
9
10
C H
H
H
H
Methane
CH4
H
C C C C
H H H
H
H H H H
H
Butane
C4H10
Butyl
-C4H9
Methyl
-CH3
C H
H
H
? R
H
C C C C
H H H
H
H H H H
?
Where R = any other C atom or arrangement of C atoms
R
First Ten Hydrocarbons: Properties
Name
Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane
1
2
3
4
5
6
7
8
9
10
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
C7H16
C8H18
C9H20
C10H22
Number of
Carbon Atoms
Molecular
Formula
Melting
Point, oC
# of
Isomers
Boiling
Point, oC
-182.5
-183.2
-187.7
-138.3
-129.7
-95.3
-90.6
-56.8
-53.6
-29.7
-161.5
-88.6
-42.1
-0.5
36.1
68.7
98.4
125.7
150.8
174.0
1
1
1
2
3
5
9
18
35
75
Properties of Alkanes
Compound
Methane
Ethane
Propane
Butane
Pentane
MW
16
30
44
58
72
Boiling point (°C)
-164
-88.6
-42.1
-0.5
+36.0
Linear Alkanes:
1 - 4 C atoms: gas at room temp
5 - 15 C atoms: liquid at room temp
>15 C atoms: solid at room temp
Larger molecular weight → Stronger London dispersion forces
Nonpolar → only London Dispersion Forces IMF
Formula
CH4
C2H6
C3H8
C4H10
C5H12
Fractional
Distillation of
Crude Oil
Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 429
Naming Branched Alkanes (IUPAC)
1. Root name: name of longest continuous C chain (parent chain)
• 2 equally long? Choose the one with more branches
2. Number C atoms in chain, starting at end with first branch
3. Identify substituents, give each a number (C it is connected to)
• Two or more identical substituents: use prefixes (di-, tri-, tetra-, etc.)
4. List substituents alphabetically before root name
• Do not alphabetize prefixes
5. Punctuation: commas separate numbers from each other
hyphens separate numbers from names
no space between last substituent & root name
4-ethyl-3,5-dimethyloctane
1
2
3
6 5
8
7 4
4-ethyl
3-methyl and 5-methyl = 3,5-dimethyl
Octane
Common Names of other Alkyl Substituents
isopropyl
isobutyl
sec-butyl
tert-butyl
alphabetized as “i”
alphabetized as “i”
alphabetized as “b”
alphabetized as “b”
CH CH2 CH3
CH3
C CH3
CH3
CH3
CH CH3CH2
CH3
CH CH3
CH3
R
R
R
R
R
R
R
R
Remember that R = any carbon chain
“iso” indicates symmetry
3 carbons
4 carbons
2o
2o
Secondary carbon
Tertiary carbon
3o 3o
H
C H
H
H C C C
H H
H H H
C
H
H H
2 - methylbutane butane
Naming Practice
Expanded Structure Line Structure
H C
C C C
H
H
CH3
CH3 H H
H
C
C
H
H
H
H
H
hexane 3,3-dimethyl
1 2 3
4
5
6 1
2
3
4 5 6
hexane 4,4-dimethyl
Lowest sum of numbers
is correct
Naming Practice
Line Structure
Isomers
The fat dog shook himself, and then rolled over on the
wet rug.
The dog shook the fat rug, then rolled over and wet on
himself.
These two statements use the same words...
but have very different meanings!
OR
Likewise, isomers may have the same formula, but
have very different structures…
Structural Isomers of C4H10
2-methylpropane
or
Structural Isomer Practice • On piece of your own paper, draw AND name
ALL of the isomers for the following alkanes:
Formulas # isomers
If you complete that, try to draw and name all of the
isomers for octane (C8H18). There are 18 of them!
Some of your drawings may look different, but they are
only different structures (isomers) if they also have
different names
Pentane
Hexane
Heptane
C5H12
C6H14
C7H16
3
5
9
Structural Isomers: Pentane (C5H12)
pentane
2-methylbutane
2,2-dimethylpropane
Structural Isomers: Hexane (C6H14)
hexane
2-methylpentane
3-methylpentane
2,3-dimethylbutane
2,2-dimethylbutane
Structural Isomers: Heptane (C7H16)
heptane
2-methylhexane
3-methylhexane
2,2-dimethylpentane
2,3-dimethylpentane
Structural Isomers: Heptane (C7H16)
2,4-dimethylpentane
3,3-dimethylpentane
3-ethylpentane
2,2,3-trimethylbutane
Comparing Structural Isomers
C5H12
(Same formula, different structure)
More branching → weaker London dispersion forces
36.0 pentane
27.9 2-methylbutane
9.5 2,2-dimethylpropane
Boiling point (°C) Name Structure
BP/MP of Linear alkanes > BP/MP of branched alkanes
Chemical Bingo: Naming Review • There are 27 structures or names drawn
on the next slide. Select 24 of them to be
placed on your bingo card.
• Because of space issues, I would number
each bingo square and then list the names
or structures on a separate sheet of paper
• If I give you a name, you must match it to
a structure. If I give you a structure, you
must match it to a name
• Any bingo winner will be awarded 1 bonus
point on the quiz (5% pts)
Chemical Bingo: Alkanes
R
R
R
R
isopropyl sec-butyl
tert-butyl isobutyl
decane nonane
2,3,4,5-tetramethylhexane
3,4-diethylhexane
3,5-diethyl-4-isopropylheptane
4-tert-butyl-3,5-dimethylheptane
4-ethyl-2,2,3,5,6,6-hexamethylheptane
Any isomer of C5H12
Any isomer of C6H14
Any isomer of C7H16
Reactions of Alkanes
Combustion
• exothermic reaction
• alkanes used as fuel source
C4H10 + ___ O2 ___ CO2 + ___ H2O 4 5 13/2
Incomplete Combustion with insufficient O2 produces CO
• Poor ventilation, cigarettes
C4H10 + ___ O2 ___ CO + ___ H2O 4 5 9/2
CO is poisonous because it binds to the hemoglobin in the blood,
preventing the absorption of O2
Radical Halogenation Terms
• Mechanism
– How the reaction occurs through multiple
steps (most reactions actually occur in many
steps)
• Chain Reaction
– Reactions that occur on their own after some
initiating event
• Free Radicals
– Atoms that have one free electron—highly
reactive
Radical Halogenation Terms
• Initiation Step
– Step where a bond is split by heat/light,
producing free radicals
• Propagation Step
– Step where free radicals react with non-
radicals, producing more free radicals and
continuing the “chain reaction”
• Termination Step
– Step where free radicals react with each
other, producing non-radicals and terminating
the “chain reaction”
Initiation
Propagation
Propagation
Termination
Reactions of Alkanes Radical Halogenation of Alkanes
Mechanism (chain reaction):
Step 1 Cl2 ⇌ Cl· + Cl ·
Step 2 Cl· + CH4 CH3· + HCl
Step 3 CH3· + Cl2 CH3Cl + Cl·
Step 4 Cl· + Cl· Cl2
Overall reaction: CH4 + Cl2 CH3Cl + HCl
Halogenated product is a haloalkane
Naming: halogen atom is a substituent, replace –ine ending with –o
-F fluoro -Cl chloro -Br bromo -I iodo
chloromethane
h (Free Radicals)
Why not 1-chloromethane?
Type of Step
CH4 + Cl2 CH3Cl + HCl
Radical Halogenation of Alkanes Halogen substitutes for hydrogen in alkane →multiple results
CH4 CH3Cl CH2Cl2 CHCl3 CCl4
Cl2
Cl2
Cl2
Cl2
Compound
CH3Cl
CH2Cl2
CHCl3
CCl4
IUPAC Name
Chloromethane
Dichloromethane
Trichloromethane
Tetrachloromethane
Common Name
Methyl chloride
Methylene chloride
Chloroform
Carbon tetrachloride
All are liquids at room temperature
• Heavy Cl atoms increase LDF
• Polar C-Cl bonds – can have polar molecules
Textbook Resource
Chemistry: An Intro to General,
Organic and Biological Chemistry
by Timberlake (Green/Tan Book)
Sections 10.1-10.6 already covered
Currently Section 11.2 (Haloalkanes)
Can be used as an outside reference
1 2 3
4 5
6
Naming Practice: Haloalkanes
F Cl
F
Cl
IBr
Cl
Br
5-chloro-2-fluorohexane
2-chloro-5-fluorohexane 2-chloro-4-fluoro-2,3-dimethylpentane
2-bromo-3-ethyl-4-iodopentane 2-bromo-4-chloro-3-isopropylpentane
Two equal numbering options?
Number based on alpha order 1
2
3 4
5
6
Radical Halogenation: Predict the Product
ClCl
?
BrBr
+ Cl2 → OR
1-chloropropane 2-chloropropane
+ Br2 → OR
1-bromo-2-methylbutane 2-bromo-2-methylbutane
Remember that any H on the alkane can be replaced by a halogen
ClOR
3-chloropropane?
+ HCl ?
?
Radical Halogenation: Predict the Product
BrBr
BrBr
Br
+ Br2 → OR
OR OR
1-bromo-2-methylbutane
2-bromo-3-
methylbutane 1-bromo-3-
methylbutane
1-bromo-2-
methylbutane
2-bromo-2-methylbutane
Structural Isomers
What are the possible structural isomers of C3H7Br?
BrBr
1-bromopropane 2-bromopropane
What are the possible structural isomers of C4H9Cl?
Cl
Cl
Cl
Cl
1-chlorobutane
2-chlorobutane
2-chloro-2-methylpropane
1-chloro-2-methylpropane
Structural Isomer Practice On piece of your own paper, draw AND name
ALL of the isomers with the following formulas:
Formulas # isomers
Some of your drawings may look different, but they are
only different structures (isomers) if they also have
different names
C4H9I
C3H6Cl2
C5H11Br
C4H8Cl2
4
4
8
9
To be honest, there may be more…this is what I
found, so try and prove me wrong! Extra Credit to
anyone who can find more structures…
Structural Isomers: C4H9I
II
II
1-iodobutane
2-iodo-2-methylbutane
2-iodobutane
1-iodo-2-methylbutane
I
I I
I
Structural Isomers: C3H6Cl2
Cl
ClCl
Cl
ClClClCl
1,1-dichloropropane
1,3-dichloropropane
1,2-dichloropropane
2,2-dichloropropane
Structural Isomers: C5H11Br
BrBr
BrBr
1-bromopentane 2-bromopentane
1-bromo-3-methylpentane 3-bromopentane
Structural Isomers: C5H11Br
Br
Br
Br
Br
1-bromo-2-methylbutane 2-bromo-3-methylbutane
1-bromo-2,2-dimethylbutane 2-bromo-2-methylbutane
Structural Isomers: C4H8Cl2
Cl
ClCl
Cl
Cl
Cl
ClCl
1,1-dichlorobutane 1,2-dichlorobutane
1,3-dichlorobutane 1,4-dichlorobutane
Structural Isomers: C4H8Cl2
Cl Cl
Cl
Cl
Cl
Cl
ClCl
Cl
Cl
2,2-dichlorobutane
1,1-dichlorobutane
2,3-dichlorobutane
1,2-dichloro-2-methylpropane
1,3-dichloro-2-methylpropane
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