Chapter 12
Organic Chemistry:
Fuels and Materials
Peak Oil??? M. King Hubbert predicted the US
production would peak in 1970…and he was
right!
Clausius-Clapeyron Equation
Pine Oil The smell of fresh cut pine is due in part to
the cyclic alkene pinene, whose structure is shown in
Figure P12.47. Use the data in the table to calculate
the heat of vaporization, ΔHvap, of pinene.
Vapor Pressure (Torr)
Temperature (K)
760
429
515
415
340
401
218
387
135
373
Problem 12.47
ln(P) vs. 1/T
7
6.5
y = -4936.4x + 18.14
6
ln(P)
5.5
Linear (ln(P))
5
4.5
4
0.0023
0.00235
0.0024
0.00245
0.0025
0.00255
0.0026
0.00265
0.0027
Clausius-Clapeyron Equation
ln(Pvap) = -DHvap/R (1/T) + C
This equation suggests
that if the vapor
pressure is known that
the enthalpy of
vaporization (DHvap)can
be calculated.
This equation generally
holds true for small
values of DT as DHvap
values typically change
with temperature.
Petroleum Refineries use
hydrocarbon volatility to
separate marketable
fractions of crude oil.
The more volatile
fractions have a greater
vapor pressure.
Raoult’s Law
Ptotal = SciP°I
DNA
(deoxyribonucleic
acid) is the blueprint
for all cellular
structure and
function.
All functions of DNA
depend on
interactions with
proteins.
Thus the importance
of understanding
and modeling these
interactions can not
be understated.
Organic Chemistry
• Organic chemistry is the study of the
compounds of carbon, in which carbon
atoms are bound to other carbon atoms,
to hydrogen atoms, and to atoms of
other elements (esp. N, O, S, P).
• Organic chemistry spans many diverse
fields from drug discovery, material
sciences, biology and the origins of live.
Organic Chemistry
• Polymers or macromolecules are very
large molecules with high molar masses
(e.g. latex, nylon or DNA and proteins)
• Oligomers are molecules that contain a
few monomers; this is the middle
ground between small molecules and
polymers.
• Monomers are small molecules that
bond together to form polymers.
Common Orgainic Functional Groups
Alkane
R-H
Alkene
Alkyne
Aromatic
Alcohol
R-OH
Ether
R-O-R
O
Aldehyde
C
R H
O
Ketone
C
R R
O
Carboxylic Acid R C OH
O
C
Ester
R OR
O
Amide
C
R NH2
Amine RNH2, R2NH, R3N
Hydrocarbons
• Alkanes are hydrocarbons in which all
the bonds are single bonds.
• Alkenes are hydrocarbons containing
one or more carbon-carbon double
bonds.
• Alkynes are hydrocarbons containing
one or more carbon-carbon triple bonds.
Alkanes are saturated hydrocarbons
common in gasoline and oils.
n-alkanes are straight chains, i.e. each
carbon atom is bound to no more than two
other carbon atoms. They have the
general formula:
CH3(CH2)nCH3
Or
CnH2n+2
Cycloalkanes are formulated “cuts” of
crude oil and are commonly C5 – C12, but
have the formula: CnH2n.
Hexane
Conformations of Cyclohexane
DHf= -167kJ/mole
DHf= -123 kJ/mole
DE= 33 kJ/mole
Melting Points and Boiling points for n-alkanes
Melting Points and Boiling Points for Selected Alkanes
Mp (oC)
Bp(oC)
-190
-42
-138
-0.5
CH3(CH2)3CH3
-130
36
CH3(CH2)4CH3
-95
69
-91
98
-57
126
-54
151
Formula
CH3CH2CH3
CH3(CH2)2CH3
CH3(CH2)5CH3
CH3(CH2)6CH3
Use
Gaseous
Fuels
Gasoline
CH3(CH2)7CH3
CH3(CH2)10CH3
through
CH3(CH2)16CH3
Diesel Fuel
and
Heating Oil
-10
216
28
316
CH3(CH2)18CH3
through
CH3(CH2)32CH3
Paraffin
Candle
Wax
37
343
72-75
na
CH3(CH2)34CH3
higher homologs
Asphalt
72-76
na
Melting Points of n-alkanes
Alkanes having more than three carbons can
be formulated into branched alkanes.
Iso-octane is used to rate gasoline for
combustion or “anti-knock” properties.
Table 12.3 Octane Ratings
Formula
Name
C5H12
Pentane
2-methybutane
Hexane
2-methylpentane
Heptane
2,2,3-trimethylbutane
C6H14
C7H12
Octane
Rating
66
104
22
82
0
112
Alkane Isomerism
Number of Alkane Isomers
Molecular Formula
Possible # Isomers
C4H10
2
C5H12
3
C6H14
5
C7H16
9
C8H18
18
C9H10
35
C10H22
75
C15H32
4,374
C20H42
366,319
Physical Constants of Hexane Isomers
Formula Name
mp(°C)
bp(°C) D(g/mL) nD
C6H14
n-hexane
-95
68.7 0.6594
1.3748
C6H14
2-methyl
pentane
-154
60.3 0.6532
1.3714
C6H14
3-methyl
pentane
2,2-dimethyl
butane
3,3-dimethyl
butane
-118
63.3 0.6643
1.3765
-129
58 0.6616
1.3750
-98
49.7 0.6492
1.3688
C6H14
C6H14
•Rules for naming alkanes
•
H
•
H
H
H
H
H H-C-H H
•
|
|
|
|
‫׀‬
•
H-C—C—C—C-H
|
‫׀‬
H-C —C —C-H
•
|
|
|
|
|
|
|
•
H
H
H
H
H
H
H
1.
Locate the longest carbon chain, or backbone, of the
molecule.
2.
Assign a base name that corresponds to the number of
carbon atoms in the longest chain. Thus, the name of the isomer
of butane in the left-hand structure shown above should rightly be
butane because there are four carbon atoms in its backbone. The
isomer depicted in the right-hand structure has only a threecarbon backbone, and so it has the base name propane.
3.
The name of a linear, or straight-chain, alkane is simply its
base name, though the names of these normal alkanes may be
preceded by n- Thus, butane is sometimes referred to as nbutane.
4.
The name of an isomer with substituents bonded to one or
more middle carbon atoms includes the names of the backbone
with a prefix that includes:
a)
the number(s) of the carbon atom(s) to which the
substituents are bonded;
b)
the number of substituents (if there is more than
one) of each type using the appropriate prefix – e.g., di for 2, tri for
3, and tetra for 4; to name the substituents.
The substituent names are listed alphabetically. And
numbering is done to keep the numbers as low as possible.
Structural Isomers of Octane
Name these structures
Problem
Draw the Lewis structures of the following.
(a) 2-methylpentane
(b) 2,3-dimethylhexane
(c) 2,3-dimethylbutane
(d) 2-methyl-3-ethylpentane
Alkenes and Alkynes
• Alkenes and alkynes are unsaturated
hydrocarbons.
• The reaction of an unsaturated
hydrocarbon with hydrogen is called
hydrogenation.
Examples
Terms
• A homologous series is a set of related
organic compounds that differ from one
another by the number of subgroups,
such as -CH2-, in their molecular
structure.
• A methylene group (-CH2-) is a
structural unit that can make two bonds.
• A methyl group (-CH3) is a structural
unit that can make only one bond.
Structural Isomers
Comparing Structural Isomers
n-Butane
2-Methylpropane
CH3CH2CH2CH3
CH3CH(CH3)CH3
Melting Point (oC)
-138
-160
Boiling Point (oC)
0
-12
Density of Gas
(g/L)
0.5788
0.5934
Structural Formula
Carbon-skeleton
n-Alkanes
Formula
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
C7H16
C8H18
C9H20
C10H22
Structural Formula
CH4
CH3CH3
CH3CH2CH3
CH3CH2CH2CH3
CH3CH2CH2CH2CH3
CH3CH2CH2CH2CH2CH3
CH3CH2CH2CH2CH2CH2CH3
CH3CH2CH2CH2CH2CH2CH2CH3
CH3CH2CH2CH2CH2CH2CH2CH2CH3
CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
Name
Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane
Octane
Nonane
Decane
Naming Alkanes
1.
2.
3.
4.
5.
Find the longest continuous chain of carbon atoms to
assign the parent name.
Find whatever groups that are not apart of the longest
continuous chain. Name these as prefixes.
Assign numbers to the groups by counting from one end
of the chain. A chain has two end so start with the end
closest to the groups.
If there are two or more identical groups, we use prefixes
to designate the number. di - 2, tri - 3, tetra - 4, penta - 5,
etc.
If there are two or more different groups, we put all of
them into the prefix in alphabetical order.
Some Common Alkyl Groups
Number of
Carbon Atoms
Structure
Name
1
2
CH3CH3CH2-
Methyl
Ethyl
3
CH3CH2CH2|
CH3CHCH3
Propyl
4
CH3(CH2)2CH2(CH3)2CHCH2|
CH3CHCH2CH3
(CH3)3C-
Isopropyl
Butyl
Isobutyl
Sec-butyl
tert-Butyl
Naming Examples
Cycloalkanes
Carbon atoms in alkanes have tetrahedral
geometry, therefore cycloalkanes are not
planar structures.
Refineries use
Fractional
Distillation
Simple and Fractional Distillation
Graph
Raoult’s Law & Fractional Distillation
Raoult’s Law
• Ptotal = X1P1 + X2P2 •••
• Raoult’s Law applies to ideal solutions
• Ideal solutions have similar strengths of
solute-solvent, solvent-solvent, and
solute-solute intermolecular interactions.
Behavior of Nonideal
Solutions
Alkenes and Alkynes
Melting and Boiling Points of Alkenes and Alkynes
Formula: Alkene
Mp(oC)
Bp(oC)
H2C=CHCH3
-185
-47
H2C=CHCH2CH3
-185
-6
H2C=CH(CH2)2CH3
-138
30
H2C=CH(CH2)3CH3
-140
63
H2C=CH(CH2)4CH3
-119
94
H2C=CH(CH2)5CH3
-104
123
H2C=CH(CH2)6CH3
-81
146
H2C=CH(CH2)7CH3
-87
174
HCCCH3
-102
-23
HCCCH2CH3
-126
8
HCC(CH2)2CH3
-90
40
HCC(CH2)3CH3
-132
71
HCC(CH2)4CH3
-81
100
Formula: Alkyne
Isomers
• Geometric isomers are structures in which
molecules with the same connectivity have
atoms in different positions because of
restricted rotation.
• A cis isomer (or Z isomer) has two like groups
on the same side of a line drawn through the
double bond.
• A trans isomer (or E isomer) has two like
groups on opposite sides of a line drawn
through the double bond.
Example
Naming Alkenes and Alkynes
• The suffix -ene is used when double bonds are
present or -yne when triple bonds are present.
• When a chain has 4 or more carbons, the chain is
numbered for the position of the multiple bond. The
position must be the lowest possible value.
• The longest chain must include the multiple bond.
• Compounds with two or more double bonds are given
the suffixes diene, triene, and so on.
Practice
Name the following compound.
CH3CH=CCH2CH3
CH2CH3
Polymers of Alkenes
n CH2=CH2 ---> -[CH2CH2]-n
Other Polymers
Aromatic Compounds
Structural Isomers of Aromatic
Compounds
Polymers Containing Aromatic
Rings
Alcohols
• Ethanol CH3CH2OH (grain alcohol)
fermentation of sugars
• Methanol CH3OH (wood alcohol)
• Isopropyl Alcohol (CH3)2CHOH (rubbing
alcohol, 2-propanol)
Solubility of Alcohols in Water at 20oC
Formula
Water Solubility (g/100mL)
CH3OH
Miscible in all proportions
CH3CH2OH
CH3CH2CH2OH
CH3(CH2)2CH2OH
Miscible in all proportions
Miscible in all proportions
Miscible in all proportions
CH3(CH2)3CH2OH
CH3(CH2)4CH2OH
CH3(CH2)5CH2OH
CH3(CH2)6CH2OH
7.9
2.3
0.6
0.2
CH3(CH2)7CH2OH
0.05
Ethers
• Ethers - compounds having an oxygen
atom between two carbon atoms (C-O-C).
• R-H
H-O-H
H-R’
R-O-R’
Functional Groups Affect Physical Properties
Molar
Mass
(g/mol)
Bp (oC)
Solubility in Water
(g/100mL at 20oC)
74
35
6.9
72
36
0.0038
74
117
7.7
CH3CH2-O-CH2CH3
O
Diethyl Ether
CH3CH2CH2CH2CH3
n-Pentane
CH3CH2CH2CH2OH
OH
n-butanol
Polymer of Alcohols and Ethers
Carbonyl Groups
Synthesis of Polyesters
Synthesis of Polyamides
Kevlar
Amines
RNH2
Primary Amine
R2NH
Secondary Amine
R 3N
Tertiary Amine
ChemTour: Structure of
Cyclohexane
Click to launch animation
PC | Mac
This ChemTour explores the structure of cyclohexane, a
common cyclic alkane in gasoline. Students can manipulate
an interactive energy diagram and observe the energy
changes that occur as the molecule cycles between chair
and boat conformation.
ChemTour: Fractional Distillation
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PC | Mac
This ChemTour shows how differences in boiling points are
used to separate a mixture of volatile molecules, such as
crude oil. Includes follow-up questions.
ChemTour: Structure of Benzene
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PC | Mac
In this ChemTour, students explore the delocalized nature of
the carbon–carbon double bonds of benzene.
ChemTour: Polymers
Click to launch animation
PC | Mac
This ChemTour animates the condensation and addition
polymerization used to form such polymers as silk, rayon,
and spandex. Includes Practice Exercises.