Organic Chemistry and Polymers -- Chapter 20
1. Introductory Topics
Bonding and Structure Concepts
Review Chapters 9 and 10
(especially Lewis dot formulas, VSEPR, and Valence Bond Theory)
Types of Chemical Formulas
e.g.,
2-propanol (iso-propanol)
H
OH
H O H
H C C C H
CH3 CH CH3
or
H H H
OH
expanded
CH3CHCH3
OH
fully condensed
formula
formula
(missing C's and H's
are understood)
condensed
formula
! ! ! Always FOUR BONDS to Carbon ! ! !
Structural Isomers - same chemical formula, but different
arrangement (connectivity) of atoms
e.g., C3H8O
- 3 isomers (2 alcohols, 1 ether)
OH
CH3 CH2 CH2 OH
CH3 CH CH3
1-propanol
2-propanol
CH3 CH2 O CH3
ethyl methyl ether
number of possible isomers can be very large, e.g.:
C3H8
1
C4H10
2
C5H12
3
C6H14
5
1
C8H18
18
C10H22 C20H42
75
> 105
Optical Isomers
(aka enantiomers)

non-superimposable mirror images

occur when four different groups are attached to a
tetrahedral (sp3) carbon center, i.e., a "chiral center"

all physical and most chemical properties are the same
but enantiomers interact differently with other chiral
molecules
e.g., CH3CH(Br)Cl is chiral and exhibits enantiomers because
its mirror images are not superimposable.
H 3C
H
H
C
C
Cl
Cl
Br
Br
CH3
mirror
In contrast, CH3CHCl2 is not chiral
superimposable on its mirror image.
H 3C
H
H
C
C
Cl
Cl
Cl
Cl
mirror
2
because
CH3
it
is
2. Organic Functional Groups
Tremendous Variety of organic molecular structures and
properties are possible, e.g.:
H
H
C
C
H
Cl
H
H
C
C
H
Cl
n
poly(vinyl chloride)
"PVC"
vinyl chloride
O
CH3
O
C
OH
O
OH
C
acetic acid
aspirin
O
H3C
O
C
CH3
O
CH3
H
N
N
CH3
N
CH3
N
H
N
caffeine
C8H10N4O2
methylamine
fortunately, the subject is very systematic !
and is readily classified by "organic functional groups"
3
Organic Functional Groups
Family
Hydrocarbons
Alkanes
Alkenes
Alkynes
Aromatic
Characteristic
Structural Feature
Examples
only single bonds
C=C
CC
CH3CH3
CH2=CH2
HCCH
benzene ring
Alcohols
R-OH
CH3CH2OH
Ethers
R-O-R'
CH3OCH3
Aldehydes
O
R C H
O
CH3 C H
Ketones
O
R C R'
O
CH3 C CH3
Carboxylic Acids
O
R C OH
O
CH3 C OH
Esters
O
R C OR'
O
CH3 C OCH3
2
RNH2
RNHR'
CH3NH2
(CH3)2NH
3
RNR'R"
(CH3)3N
O H (R')
R C N
H (R")
O
CH3 C NH2
Amines:
Amides
1
4
3. Hydrocarbons
(a) Alkanes
CH4
C2H6
C3H8
C4H10
CnH2n+2
methane
ethane
propane
butane
C5H12
C6H14
C7H16
C8H18
pentane
hexane
heptane
octane, etc......
alkyl groups
methyl
CH3
H
H C
H
ethyl
CH3CH2
phenyl
C6H5
H H
H C C
H H
Nomenclature of alkanes
(see book for "rules")
e.g.,
CH3 CH3 CH3
CH3CH2CHCHCHCH2CHCH3
CH2CH3
5-ethyl-2,4,6-trimethyloctane
5
Reactions of alkanes
(generally unreactive)
free radical substitution (not selective!)
C2H6
+

Cl2
C2H5Cl
+
HCl
dehydrogenation (reverse Rx is more common!)

C2H6
H2C=CH2
+
H2
"cracking" of hydrocarbons (petroleum industry)
(b) Alkenes
~ C=C double bond
CnH2n (with one double bond)
Geometric Isomers are possible, e.g.:
H3C
H3C
CH3
C
H
H
C
C
H
H
cis-2-butene
C
CH3
trans-2-butene
 restricted C=C bond rotation
 trigonal planar geometry at C=C carbons
 sp2 hybridization at C=C carbons
Nomenclature
(C=C bond takes preference)
CH3
CH3
CH3CH2CHCH2CH CCH3
2,5-dimethyl-2-heptene
6
cyclohexene
Reactions of alkenes ~ addition to double bond

RCH=CH2 + HX
R
RXCH-CH3
H
C
C
H
+
H
X-
X
H
H
C
H
X
X
RCH
R
+C
CH3
R
H
H
H
C
H
C
H
H
Markarnikov's rule ~ "them that has, gets"
(H goes on the C that already has the most H's)
addition of non-polar reagents (H2, Br2, etc.) also occurs
(c) Alkynes
~
CnH2n-2
CC triple bond
(with one triple bond)
 linear geometry at CC carbons
 sp hybridization at CC carbons
 no "cis - trans" isomers
 similar addition reactions as alkenes
(stepwise addition can occur)
X
R
C
C
H
XY
Y
C
C
R
H
7
XY
X
R
Y
C
X
C
H
Y
(d) Aromatic Hydrocarbons (Benzene and it's derivatives)
Benzene ~ C6H6




planar 6-membered ring (especially stable)
all C-C distances equivalent
sp2 hybridization at all carbons
delocalized set of 3 double bonds (6  electrons)
Derivatives of Benzene
 common names ~ monosubstituted
CH3
OH
toluene
NH2
CH CH2
aniline
phenol
styrene
 systematic names ~ disubstituted
CH2CH3
6
3
2
4
5
1
6
2
4
Br
Br
1
5
3
Br
1,2-dibromobenzene
1-bromo-3-ethylbenzene
 ortho, meta, para designators
Cl
Cl
Cl
Cl
Cl
o-dichlorobenzene
m-dichlorobenzene
8
Cl
p-dichlorobenzene
Substitution Reactions (never addition!)
X2
X
X = Cl, Br
H
H
H
HNO3
NO2
(H+ catalyst)
X2
H
H
X
( NOT aromatic ! )
H
X
other common aromatic hydrocarbons:
naphthalene
anthracenes
9
(4) Alcohols and Ethers
(organic derivatives of H2O)
Nomenclature
Alcohols, R-O-H
R = CH3
R = CH3CH2
R = CH3CH2CH2
methanol
ethanol
1-propanol (n-propanol)
OH
OH
OH
CH3CHCH3
2-propanol
(iso-propanol)
phenol
3,7-dimethyl-4-octanol
Ethers, R-O-R'
CH3CH2-O-CH2CH3
CH3-O-CH2CH2CH3
Ether Synthesis:
R
O
H
+
H
O
diethyl ether
methyl propyl ether
R
H+
R
- H 2O
O
R
Oxidation of alcohols
H
R
C
O
H
H
primary
C
- "H2"
O
R
C
H
aldehyde
O
H
R
[O]
O
H
R' secondary
[O]
- "H2"
R
C
R'
ketone
R'
R
C
O
H
R" tertiary
[O]
No Reaction
[O] = an oxidizing agent like [Cr 2O7]2-
10
Elimination Reactions of alcohols
R
H
OH
C
CH2
H
R

C
H+
H
alcohol
+
CH2
H2O
alkene
Substitution Reactions of alcohols
RCH2
OH
alcohol
+
H

X
RCH2
- H 2O
X = Cl, Br, I
X
alkyl halide
(5) Amines (organic derivatives of NH3)
CH3
N
CH3
H
N
H
CH3
CH3
H
methylamine
dimethylamine
N
H
CH2CH2CH3
methylpropylamine
NH2
NH2
2-aminohexane
aniline
like ammonia, amines are weak bases
RNH3+
RNH2 + H +
(6) Aldehydes and Ketones
Nomenclature
O
H
C
O
H
CH3
methanal
(formaldehyde)
C
O
H
CH3CH2
ethanal
(acetaldehyde)
O
CH3
C
propanone
(acetone)
CH3
O
C
CH2CH3
butanone
(methyl ethyl ketone)
11
H
propanal
O
CH3
C
5-methyl-3-heptanone
Hydrogenation (reduction) of aldehydes and ketones
O
R
C
OH
"H2"
H
R

H
aldehyde
O
R
C
C
primary
alcohol
OH
"H2"
R'
H
R

C
H
ketone
R'
secondary
alcohol
Oxidation of aldehydes (very easy!)
O
O
R
C
[O]
H
R
aldehyde
C
O H
carboxylic acid
(7) Carboxylic Acids and Esters
Nomenclature of Acids
O
H
C
O
O
O H
CH3
methanoic acid
(formic acid)
C
C
O H
ethanoic acid
(acetic acid)
O H
benzoic acid
O
CH3CH2CH2 C OH
CH3CH2CH2CO2H
butanoic acid
(condensed formula)
Salts of Acids
O
O
CH3
C
O H
acetic acid
NaOH
H2O
12
CH3
C
O- Na+
sodium acetate
Nomenclature of Esters
O
R
O
alkyl group
C
O R'
CH3
C
O CH2CH3
ethyl acetate
acid name
-ate
O
CH3CH2CH2
C
O
O CH2CH3
C
ethyl butanoate
O CH3
methyl benzoate
Formation of Esters (from acid + alcohol)
O
R
C
O
+
O H
H O R'
R
C
+
O R'
H2O
Saponification of Esters (hydrolysis)
O
CH3
C
O
O CH2CH3
ester
NaOH
H2O
CH3
C
O- Na+
salt of acid
+
HOCH2CH3
alcohol
Soap ~ salt of long chain carboxylic acid
O
O- Na+
non-polar hydrocarbon "tail"
13
polar "head"
(8) Amides
acid derivatives (e.g., 1 amides: -NH2 instead of -OH)
O
R
C
O
O H
+
H NH2
R
C
H
N
H
+
H2O
Nomenclature
R = CH3
ethanamide
R = CH2CH2CH2CH3
pentanamide, etc.
amides (unlike amines) are generally not basic
(due to e- withdrawing effect of the C=O group)
Organic Polymers
(1) Polymers -- macromolecules made up of many repeating
units called monomers
e.g.,
polystyrene is formed via the polymerization of the
monomer, styrene:
n HC
CH2

CH
h
CH2
n
n ~ 103 - 106
styrene
e.g.,
polystyrene
some rings can open to form polymers:
O
CH2 CH2 CH2 CH2 O
n
14
(2) Types of polymer structures
Homopolymers
A
A
A
A
A
A
A
A
linear
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
branched
A
cross-linked
A
A
A
A
A
A
Solubility
linear and branched -- usually soluble
cross-linked -- insoluble (swell)
Elastomer
a lightly cross-linked polymer
Copolymers -- contain two or more different monomers,
combine properties of 2 polymers
A
B
A
B
A
A
B
alternating copolymer
(or random)
A
A
A
A
A
B
B
B
block copolymer
15
B
B
A
A
A
B
B
B
B
B
A
A
graft
copolymer
A
(3) Methods of Polymerization
Addition (very common -- works with most alkenes)
CH2 CH2 + CH2 CH2 + CH2 CH2
etc.....
CH2 CH2 CH2 CH2 CH2 CH2
requires an initiator (e.g., a catalyst or UV light)
to start the "chain" reaction
Condensation (common for polyesters and polyamides)
a small molecule (e.g., H2O) byproduct is formed
+
X A Y
Ring-Opening
A
- XY
X B Y
A B
n
(uncommon except for polyethers and
most inorganic polymers, e.g., silicones)
B
A
B A
B A
B A
etc....
(4) Common Addition Polymers
Monomer
Polymer
CH2 CH2
n
polyethylene
CH2 CH2
ethylene
HC
CH2
CH
styrene
CH2
polystyrene
16
n
HC CH2
Cl
CH
Cl
vinyl chloride
HC
CH
CH2
CH2
n
N C
"Orlon"
cyanoethene
CH3
(ester)
CH2 C
CO2CH3
CH3
CH2 C n
CO2CH3
methyl methacrylate
"plexiglas" (Lucite)
C N
CH2 C
CO2CH3
C N
CH2 C n
CO2CH3
methyl cyanoacrylate
"super glue"
CF2
CF2
n
"Teflon"
CF2
tetrafluoroethene
H C
n
poly(vinyl chloride) ~ PVC
N C
F2C
CH2
H
C
C H
acetylene
(ethyne)
C
n
H
poly(acetylene)
Addition polymerization of dienes
CH3
CH3
CH2
C
CH
CH2
CH2
"isoprene"
(2-methyl-1,3-butadiene)
C
CH
CH2
"natural" rubber
17
n
(5) Common Condensation Polymers
Polyesters
O
O
H O C A C O H
+
H O B O H
diacid
diol
O
O
C A C O B O
n
polyester
e.g.,
A =

- H 2O
B =
O
C
CH2 CH2
O
C O CH2 CH2 O
n
"Dacron"
Polyamides (nylons)
O
O
H O C A C O H
+
diacid
H
H
H N B N H
diamine
O
O
C A C N B N
n
H
H
polyamide
e.g.,
A =

- H 2O
B =
(CH2)4
O
O
C (CH2)4 C N (CH2)6 N
n
H
H
e.g.,
(CH2)6
nylon-66
A = B =
O
C
O
C N
H
N
n
H
18
"Kevlar"