1. 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

2. Hydrocarbons  Simplest class of organic compounds
 Consist entirely of carbon and hydrogen
 Four major classes of hydrocarbons:
1. Alkanes — contain only carbon-hydrogen and carbon- carbon single bonds
2. Alkenes — contain at least one carbon-carbon double bond
3. Alkynes — contain a least one carbon-carbon triple bond
4. Aromatics — contain rings of six carbon atoms that can be drawn with alternating single and double bonds
 Alkanes are saturated hydrocarbons; alkenes, alkynes, and aromatics are unsaturated hydrocarbons
Copyright 2007 Pearson Benjamin Cummings. All rights reserved.

3. Hydrocarbons  Alkanes
– Names of all alkanes end in –ane, and their boiling points increase with more carbon atoms present.
– The simplest alkane is methane.
– In larger alkanes, carbon atoms are joined in an unbranched chain (straight-chain alkanes) where each carbon atom is bonded to two other carbon atoms.
– Alkanes with four or more carbon atoms can have more than one arrangement of atoms. Carbon atoms can form a single, unbranched chain, or the primary chain of carbon atoms can have one or more shorter chains that form branches.
– The systematic name for branched hydrocarbons uses the lowest possible number to indicate the position of the branch along the longest straight carbon chain in the structure.
Copyright 2007 Pearson Benjamin Cummings. All rights reserved.

4. Hydrocarbons  Alkenes
– The simplest alkenes are ethylene and propylene.
– Names of alkenes that have more than three carbon atoms use the same stems as the names of alkanes
but end in –ene.
– More than one structure is possible for alkenes that contain four or more carbons.
– The number in the name of an alkene specifies the position of the first carbon atom of the double bond. The name is based on the lowest possible number starting from either end of the carbon chain.
Copyright 2007 Pearson Benjamin Cummings. All rights reserved.

5. Hydrocarbons – The simplest alkyne is acetylene.
 Alkynes
– The simplest alkyne is acetylene.
– The names of alkynes are similar to those of the corresponding alkanes but end in –yne.
Copyright 2007 Pearson Benjamin Cummings. All rights reserved.

6. Hydrocarbons  Cyclic hydrocarbons
– The ends of a hydrocarbon chain are connected to form a ring of covalently bonded carbon atoms.
– Cyclic hydrocarbons are named by attaching the prefix cyclo- to the name of the alkane, alkene, or alkyne.
– The simplest cyclic alkanes are cyclopropane and cyclobutane
– Draw structures of cyclic alkanes by sketching a polygon with the same number of vertices as there are carbon atoms in the ring with each vertex representing a CH2 unit.
Copyright 2007 Pearson Benjamin Cummings. All rights reserved.

7. Hydrocarbons
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

8. Hydrocarbons  Aromatic Hydrocarbons
– Alkanes, alkenes, alkynes, and cyclic hydrocarbons are called aliphatic hydrocarbons.
– Aromatic hydrocarbons are also called arenes and are obtained by the distillation and degradation of highly scented resins from tropical trees.
– The simplest aromatic hydrocarbon is benzene.
– The chemical behavior of aromatic compounds differs from the behavior of aliphatic compounds.
– The general name for a group of atoms derived from an alkane is an alkyl group, and the name of the alkyl group is derived from the name of the alkane by adding the suffix –yl.
– Groups of atoms derived from aromatic hydrocarbons are aryl groups.
– In general formulas and structures, alkyl and aryl groups are abbreviated as R.
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

9. Hydrocarbons
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

10. Hydrocarbons Alcohols
– Replacing one or more hydrogen atom of a hydrocarbon with an –OH group gives an alcohol and is represented as R-OH.
– The simplest alcohol is methanol (systematic name) or methyl alcohol (common name).
– The simplest alcohol derived from an aromatic hydrocarbon is phenol.
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

11. Drawing Organic Structures
Shortcuts make structures easier & faster to draw
Butane: C4H10
Lewis Structure
Carbon Atoms
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
Condensed Structures
CH3CH2CH2CH3
CH3(CH2)2CH3

12. Types of Organic Compounds
Classified according to functional group
Alkane
Alkene
Alkyne
Haloalkane
Alcohol
Ether
Ketone
Aldehyde
Carboxylic acid
Amine
Amino acid
Amide

13. Big Idea in Organic Chemistry
Structure controls Function
Each functional group has predictable reactivity

14. Alkanes or Paraffin
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 1° 3° 2°
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 ”

15. Names of Linear Alkanes and Alkyl Substituents
C atoms
Alkane
Alkyl substituents 1 2 3 4 5 6 7 8 9 10
CH4
CH3CH3
CH3CH2CH3
CH3CH2CH2CH3
methane
ethane
propane
butane
pentane
hexane
heptane
octane
nonane
decane
-CH3
-CH2CH3
-CH2CH2CH3
methyl
ethyl
propyl
etc.
Root: number of C atoms
Suffix: functional group
(-ane for alkanes)
(-yl for alkyl groups)

16. H C C H
Methane
CH4
Butane
C4H10 H C ? C H ? R R
Methyl
-CH3
Butyl
-C4H9
Where R = any other C atom or arrangement of C atoms

17. First Ten Hydrocarbons: Properties
Number of
Carbon Atoms
Molecular
Formula
Melting
Point, oC
Boiling
Point, oC
# of
Isomers
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
-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 2 3 5 9 18 35 75

18. Nonpolar → only London Dispersion Forces IMF
Properties of Alkanes
Nonpolar → only London Dispersion Forces IMF
Larger molecular weight → Stronger London dispersion forces
Compound
Methane
Ethane
Propane
Butane
Pentane
Formula
CH4
C2H6
C3H8
C4H10
C5H12 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
C atoms: liquid at room temp
>15 C atoms: solid at room temp

19. Fractional Distillation of Crude Oil
Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 429

20. Naming Branched Alkanes (IUPAC)
Octane
4-ethyl 6 2 8
4-ethyl-3,5-dimethyloctane 5 4 7 3 1
3-methyl and 5-methyl
= 3,5-dimethyl
Root name: name of longest continuous C chain (parent chain)
Two equally long? Choose the one with more branches
Number C atoms in chain, starting at end with first branch
Identify substituents, give each a number (C it is connected to)
Two or more identical substituents: use prefixes (di-, tri-, tetra-, etc.)
List substituents alphabetically before root name
Do not alphabetize prefixes
Punctuation: commas separate numbers from each other
hyphens separate numbers from names
no space between last substituent & root name

21. Common Names of other Alkyl Substituents
Remember that R = any carbon chain R
3 carbons R
isopropyl
alphabetized as “i”
“iso” indicates symmetry R R
isobutyl
alphabetized as “i”
4 carbons 2o R R 2o
sec-butyl
alphabetized as “b”
Secondary carbon R 3o 3o R
tert-butyl
alphabetized as “b”
Tertiary carbon

22. Naming Practice C H 2 - methylbutane butane Expanded Structure
Line Structure H C
2 - methylbutane
butane

23. Naming Practice H H CH3 H C C C H H C H H C H H C H H 4,4-dimethyl
Line Structure 1 2 3 4 5 6 4 5 6 H H C H H C H H C H H
4,4-dimethyl
hexane
3,3-dimethyl
hexane
Lowest sum of numbers
is correct

24. Isomers
The fat dog shook himself, and then rolled over on the wet rug. OR
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!
Likewise, isomers may have the same formula, but have very different structures…

25. Structural Isomers of C4H10
2-methylpropane or

26. Structural Isomer Practice
On piece of your own paper, draw AND name ALL of the isomers for the following alkanes:
Formulas
# isomers
Pentane
Hexane
Heptane
C5H12
C6H14
C7H16 3 5 9
Some of your drawings may look different, but they are only different structures (isomers) if they also have different names
If you complete that, try to draw and name all of the isomers for octane (C8H18). There are 18 of them!

27. Structural Isomers: Pentane (C5H12)
2-methylbutane
2,2-dimethylpropane

28. Structural Isomers: Hexane (C6H14)
2,3-dimethylbutane
2-methylpentane
2,2-dimethylbutane
3-methylpentane

29. Structural Isomers: Heptane (C7H16)
2,2-dimethylpentane
2-methylhexane
2,3-dimethylpentane
3-methylhexane

30. Structural Isomers: Heptane C7H16
2,4-dimethylpentane
3-ethylpentane
3,3-dimethylpentane
2,2,3-trimethylbutane

31. Comparing Structural Isomers
(Same formula, different structure)
C5H12
Structure
Name
Boiling point (°C)
pentane
36.0
2-methylbutane
27.9
2,2-dimethylpropane
9.5
More branching → weaker London dispersion forces
BP/MP of Linear alkanes > BP/MP of branched alkanes

32. Reactions of Alkanes 13/2 4 5 9/2 4 5 Combustion
exothermic reaction
alkanes used as fuel source
13/2 4 5
C4H10 + ___ O2  ___ CO2 + ___ H2O
Incomplete Combustion with insufficient O2 produces CO
Poor ventilation, cigarettes
9/2 4 5
C4H10 + ___ O2  ___ CO + ___ H2O
CO is poisonous because it binds to the hemoglobin in the blood, preventing the absorption of O2

33. 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

34. 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

35. 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”

36. 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”

37. Radical Halogenation of Alkanes
Reactions of Alkanes
Radical Halogenation of Alkanes
Mechanism (chain reaction):
Step 1 Cl2 ⇌ 2 Cl·
Step 2 Cl· + CH4  CH3· + HCl
Step 3 CH3· + Cl2  CH3Cl + Cl·
Step 4 Cl· + Cl·  Cl2
Type of Step h
Initiation
Propagation
Termination
(Free Radicals)
Overall reaction: CH4 + Cl2  CH3Cl + HCl
 chloromethane
Why not 1-chloromethane?
Halogenated product is a haloalkane
Naming: halogen atom is a substituent, replace –ine ending with –o
-F fluoro -Cl chloro -Br bromo -I iodo

38. Radical Halogenation of Alkanes
Halogen substitutes for hydrogen in alkane →multiple results
Cl2 
Cl2 
Cl2 
Cl2 
CH4
CH3Cl
CH2Cl2
CHCl3
CCl4
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