Ch. 3 Review:
Nomenclature: Organic Compounds
• Compounds of carbon--organic chemistry
– If they have only C and H, hydrocarbons
– e.g. alkanes: methane CH4, ethane C2H6, propane C3H8
• general formula: CnH2n+2
– Know Table 3.7
• Functional Groups
–
–
–
–
R = hydrocarbon group
e.g. alcohols: methanol CH3OH, ethanol C2H5OH
e.g. amines: propyl amine, butylamine
Know functional groups in Table 3.8
Methanol (wood alcohol), CH3OH,
is related to methane, CH4, by
replacing one H with OH.
Organic chemistry -- Chapter 20
• Introductory Topics
Bonding & Structure -- Review Chapters 3, 9, and 10!!
Types of Chemical Formulas
e.g. 2-propanol (iso-propanol)
OH
H
H
H
O
H
C
C
C
H3C
H
CH
OH
CH3
or
OH
H
H
H
expanded
structural
formula
CH3CHCH 3
condensed
structural
formula
fully condensed
structural formula
“line drawing”
(missing C’s and H’s
are understood)
!!! Always FOUR BONDS to Carbon !!!
Isomerism
• Isomers– different molecules with the same
molecular formula
Structural isomers--different pattern of atom attachment;
different connectivity
Stereoisomers—same atom attachments (connectivity),
different spatial orientation
Rotation about a single bond is not isomerism!!
Structural Isomers
• Structural Isomers -- same chemical formula, but different
arrangement (connectivity) of atoms
e.g. C3H8O - 3 isomers (2 alcohols, 1 ether)
CH3
CH2
CH2
OH
OH
1-propanol
H3C
CH
CH3
2-propanol
CH3
CH2
O
CH3
ethyl methyl ether
Number of possible isomers can be very large, e.g.
C 3H8
C4H10
1
2
C5H12 C6H14 C8H18
3
5
18
C10H22 C20H42
75
> 105
Stereoisomers
• Stereoisomers—same atom attachments (connectivity),
different spatial orientation
• Optical isomers (enantiomers)—are molecules that are
nonsuperimposable mirror images of each other
• Geometric isomers—are stereoisomers that are not
optical isomers, e.g. cis and trans
Chiral Molecules
• Are molecules that have nonsuperimposable mirror images
– If 4 different groups are attached to carbon, it will be
chiral
– Chiral molecules will rotate plane-polarized light
– Most physical properties are identical, but in a chiral
environment enantiomers behave differently
Isomerism; Overview
7
Many Possible Compounds
A Tremendous Variety of organic molecular structures and
properties are possible, e.g.:
H
H
C
C
Cl
H
vinyl chloride
O
CH 3
C
H
H
C
C
H
Cl
n
poly(vinyl chloride)
“PVC”
O
C
OH
OH
O
acetic acid
C
O
aspirin
CH3
More Organic Compounds
O
CH 3
CH 3
N
N
N
O
H
CH 3
H
CH 3
Caffeine
C8H10N4O2
N
methylamine
fortunately, the subject is very systematic !
and is readily classified by “organic functional groups”
Hydrocarbons
• Alkanes
CH4
C 2H6
C 3H8
C4H10
CnH2n+2
methane
ethane
propane
butane
C5H12 pentane
C6H14 hexane
C7H16 heptane
C8H18 octane, etc….
alkyl groups:
H
methyl CH3
H
C
H
ethyl CH3CH2
phenyl C6H5
H
H
H
C
C
H
H
Alkane Nomenclature
1.
2.
Name parent chain--longest continuous chain
Number parent chain
-- First branch gets lowest possible number
3.
4.
Name & number branches
Order branches
-- Alphabetical order
-- Multiple identical substituents get prefix
Samples:
CH3 CH3
CH3
CH3CH2CHCHCHCH2CHCH3
Br
C
N
CH2CH3
5-ethyl-2,4,6-trimethyloctane
5-bromo-2-cyano-4-methylheptane
(see book for detailed “rules” and other functional groups)
Reactions of Alkanes
(generally unreactive)
• Combustion -- fuels!
e.g. C5H12(l) + 8 O2(g) --> 5 CO2(g) + 6 H2O(l)
• Free radical substitution (not selective!)
C2H6(g) + Cl2(g) --> C2H5Cl(g) + HCl(g)
• Dehydrogenation (reverse rxn is more common!)
C2H6(g) --> H2C=CH2(g) + H2(g)
• “Cracking” of hydrocarbons (petroleum industry)
Alkenes ~ C=C double bond
CnH2n (with one double bond)
• Geometric isomers are possible, e.g.:
CH 3
H3C
C
C
C
H
H
CH 3
H
H3C
cis-2-butene
C
H
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
cyclohexene
Reactions of Alkenes
addition to double bond
RCH=CH2 + HX --> RXCH-CH3
H
R
C
H
H
R
+
C
H
X
X
C
H
H
X
RHC
≡
X
C
H
H
H
H
R
CH 3
C
C
H
H
Markovnikov’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
Alkynes ~ C≡C Triple Bond
CnH2n-2 (with one triple bond)
•
•
•
•
linear geometry at C≡C carbons
sp hybridization at C≡C carbons
no “cis-trans” isomers
similar addition reactions to alkenes
(stepwise addition can occur)
Y
X
R
C
C H
XY
C
R
XY
C
H
Y
X
R
C
X
C
H
Y
Aromatic Hydrocarbons
(benzene and its derivatives)
Benzene ~ C6H6
•
•
•
•
planar 6-membered ring (especially stable)
all C-C distances equivalent
sp2 hydridization at all carbons
delocalized set of 3 double bonds (6 p electrons)
other common aromatic hydrocarbons:
napthalene
anthracenes
Aromatic Nomenclature
• Aromatic ring as substituent
– Phenyl (C6H5–)
– Benzyl (C6H5CH2–)
H 2C
• Monosubstituted benzene
– (name of substituent)benzene
– Some common “trivial” names
• Toluene
• Phenol
• Polysubstituted benzene
– Assign numbers to substituents
CH CH2
CH CH2
CH3
4-phenyl-1-hexene
CH2CH2CH3
propylbenzene
F
3
2
1 Br
1-bromo-3-fluorobenzene
Aromatic Substitution Rxns
• Substitution Reactions of Aromatic Hydrocarbons (never
addition!)
X2
X
X = Cl, Br
H
H
H
X2
HNO3
(H+ catalyst)
H
X
X
H
( NOT aromatic! )
NO 2
H
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-O-H
CH3CH2OH
Ethers*
R-O-R’
CH3OCH3
O
* structures like water
H
H
More Organic Functional Groups
“carbonyl” compounds
Family
Characteristic
Structural Feature
Aldehydes
O
R
Ketones
C
Carboxylic Acids
C
H
Esters
C
R'
C
H3C C
H
H3C C
CH3
O
OH
H3C C
OH
O
O
R
Examples
O
O
R
C
O
O
R
O
OR'
H3C C
OCH 3
More Organic Functional Groups
Family
Characteristic
Structural Feature
Examples
Amines: 1º
2º
3º
RNH2
RNHR’
RNR’R”
CH3NH2
(CH3)2NH
(CH3)3N
O
Amides
R
C
H (R')
N
O
H3C C
NH2
H (R")
N
Alcohols
(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
Reactions of Alcohols
Oxidation
H
R
C
H
[O]
O
H
primary
H
R
C
– “H2”
R
O
H
R
– “H2”
[O]
C
O
H
R
tertiary
C
H
aldehyde
O
[O]
R secondary
R
O
R
C
R
ketone
No Reaction
[O] = oxidizing agent, e.g. Cr2O72–
More Reactions of Alcohols
Elimination
R
H
OH
C
CH 2
H
alcohol
R
C
H+
H
CH 2
+ H2O
alkene
Substitution
RCH2—OH + H—X
alcohol
X = Cl, Br, I
– H2O
RCH2—X
alkyl halide
Aldehydes and Ketones
Nomenclature
H
C
O
O
O
H
methanal
(formaldehyde)
H3C
C
H
ethanal
(acetaldehyde)
CH3CH 2
C
H
propanal
O
O
O
H3C
C
CH 3
propanone
(acetone)
H3C
C
CH 2CH 3
butanone
(methyl ethyl ketone)
5-methyl-3-heptanone
Reactions of Aldehydes and Ketones
Hydrogenation (reduction) of aldehydes and ketones
“H2”
O
OH
R
R
C
H
aldehyde
O
R
C
“H2”
R'
C
H
H
primary
alcohol
OH
R
C
R'
H
secondary
alcohol
ketone
Oxidation of aldehydes (very easy!)
O
R
C
aldehyde
O
[O]
H
R
C
OH
carboxylic acid
Carboxylic Acids
Nomenclature of Acids
H
O
O
O
C
H3C
OH
C
C
OH
ethanoic acid
(acetic acid)
methanoic acid
(formic acid)
benzoic acid
O
CH 3CH2CH 2
C
OH
butanoic acid
CH3CH2CH2CO2H
(condensed formula)
Salts of Acids
O
H3C
C
O
NaOH
OH
acetic acid
H2O
H3C
C
O
sodium acetate
Na
OH
Condensation Reactions
• a condensation reaction is any organic reaction driven by the
removal of a small molecule, like water
• esters are made by the condensation reaction
between a carboxylic acid and an alcohol

the reaction is acid catalyzed
• acid anhydrides are made by the condensation
reaction between 2 carboxylic acid molecules

the reaction is driven by heat
+
O
R
C
OH
O
HO
C
O
R'
R
C
O
O
C
+
R'
HOH
Esters
Nomenclature of Esters
O
O
alkyl group
R
C
O R'
acid name
H3C
C
O
ethyl acetate
-ate
O
CH3CH2CH 2
C
CH 2CH 3
O
O
CH2CH3
C
O
CH 3
ethyl butanoate
methyl benzoate
Formation of Esters (from acid + alcohol)
O
O
R
C
O
H
+
H
O
R'
R
C
O
R' +
H2O
Ethers
Ethers
R – O – R’
CH3CH2–O–CH2CH3 diethyl ether
CH3–O–CH2CH2CH3 methyl propyl ether
• Ether Synthesis:
H+
R–O–H + H–O–R
– H2O
R–O–R
Amines
(organic derivatives of NH3)
H3C
N
H
H3C
N
H3C
H
N
CH 2CH 2CH3
CH 3
H
methylamine
dimethylamine
methylpropylamine
NH 2
NH 2
2-aminohexane
aniline
Like ammonia, amines are weak bases:
RNH2 + H+
H
RNH3+
Amides
Acid derivatives (e.g. 1º amides: –NH2 instead of –OH)
O
O
R
C
H
O
H
+
H
NH2
R
C
N
+
H2O
H
Nomenclature
R = CH3
R = CH2CH2CH2CH3
ethanamide
pentanamide, etc.
amides (unlike amines) are generally not basic
(due to e- withdrawing effect of the C=O group)
Sample Questions
(1) Write complete, systematic names for:
H3C
CH
H3C
C
CH 2
CH 2
C
CH 3
N
CH3
O
C
CH
O CH
H2C
CH3
O
H
C
CH 2
CH 2
CH CH 2 CH 3
Sample Questions, cont.
(2) Write complete, specific structural formulas for all of the
organic reactants and products in the reaction.
an ester
NaOH
sodium acetate + 3-pentanol
(3) Show, with specific structures and reactions, how the
following compound can be prepared in three steps starting
with the appropriate alkyne.
O
H3C
C
CH
CH3
CH3
Answers
1. 2-cyano-4-methyl-3-heptene
2-butylbenzoate
4-phenylhexanal
CH 3
2.
NaOH
CH 2
O
O
+
C
CH
C
H3C
CH3
O
CH2
3.
cat, D
CH 3
C
H
O
H3C
C
+ H2
CH
Na +
OH
H
H
pressure
CH 3
C
step 1
C
CH
H
CH 3
CH 3
H
H
C
H
+ H2O
C
CH
CH 3
CH 3
acid cat
H
H
OH
C
C
H
H
CH 3
step 2
CH
CH 3
Answers, cont.
3., cont.
H
H
O
OH
C
C
H
H
CH 3
CH
[ox]
C
H3C
CH 3
CH
CH3
CH3
Organic Polymers
Polymers -- macromolecules made up of many repeating units
called monomers
e.g. polystyrene is formed via the polymerization of the
monomer styrene:
HC
CH 2
CH
hn
C
H2
n
n ~ 103 - 106
styrene
polystyrene
e.g. some rings can open to form polymers:
O
CH2
CH2
CH2
CH2
O
n
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
More Methods of Polymerization
Condensation (common for polyesters and polyamides)
a small molecule (e.g. H2O) byproduct is formed
X-A-Y + X-B-Y
Ring-Opening
A
– XY
A
B
n
(uncommon except for polyethers and most
inorganic polymers, e.g. silicones)
B
A
B
A
B
A
B
A
etc…
Common Addition Polymers
Monomer
CH2=CH2
Polymer
—CH2–CH2—n
ethylene
polyethylene
CH=CH2
—CH–CH2—
n
styrene
CH=CH2
Cl
vinyl chloride
CH=CH2
N≡C cyanoethene
polystyrene
—CH–CH2—
Cl
n
poly(vinyl chloride) ~ PVC
—CH–CH2—
N≡C
n
“Orlon”
One More Common Addition Polymer!
Addition polymerization of dienes
CH 3
CH 3
H2C
C
CH
CH 2
“isoprene”
(2-methyl-1,3-butadiene)
CH 2
C
CH CH 2
“natural” rubber
n
Common Condensation Polymers
Polyesters
O
O
H
O C
A
C
O
H
+
diacid
H
O
B
O
H
diol
O
O
C
– H2O
A
C
O
B
O
n
polyester
e. g.
A =
B =
O
O
C
C
CH2 CH2
O
CH2
CH 2
O
n
“Dacron”
Sample Question
Write a complete structural formula of the organic polymer
that is produced in each reaction. State whether the
polymerization process is addition, condensation, or ringopening.
O
O
C
C
HO
OH
O
CH 3
C
CH 2
CH
N
+ HO-CH2CH2-OH
Answer
c. addition
a. condensation
C
O
O
N
O
CH2 CH
O
n
CH 2CH 2
n
b. ring-opening
d. addition
O
n
n