Addition Reactions

Atoms are added across a double or triple bond
Hydrogenation: H2(g) is added
H
H H
H
+
C C
H
catalyst
H2
H
R
H H
H2
R
, P
H
C OH
H
H
catalyst
+
C O
H
catalyst
+
C O
R
H C C H
, P
H2
R
, P
R'
C OH
R'
Halogenation: X2(g) is added
H
H
+
C C
H
Br2
room
temp
Br Br
H C C H
H
H H
Markovnikov’s Rule: When H-X or H-OH is added, the H bonds to the carbon that already has the most
H’s on it. In other words “the rich get richer”
Hydrohalogenation: HX is added
H
H
+ HCl
C C
H3C
room
temp
H
Cl
H C
H
C H
CH3 H
Hydration: H2O is added
H
+
C C
H3C
OH H
H
H
H2O
H2SO4
H C
C H
CH3 H
Substitution Reactions

Hydrogen atom is replaced by another atom or group of atoms
Halogenation: Halogen replaces a hydrogen when X2(g) or HX is added
H H
H
H Br
+
C C H
HBr
 or h
H H
H
+
C C H
H2
H H
Cl
+
Cl Cl
FeBr3
+
H Cl
Nitration: NO2 replaces a hydrogen when HNO3 is added
+
HNO 3
NO 2
H2SO4
+
H2O
Alkylation: An alkyl group replaces a hydrogen when RX is added
+ H3C
Br
H
N H
+
CH3
AlCl3
+
HBr
H
H3C Cl
H
N CH3
H
+
HCl
CH3
H
N CH3
+
H3C
H2C
CH2 Cl
H
N CH3
+
HCl
H
CH3
H2C
N CH3
H
CH3
+
H2C
H3C Cl
N CH3
H3C
+
HCl
Elimination Reactions


Results in loss of small molecule from larger molecule which causes a single bond to become a
double bond, and double to become a triple
When molecule is not symmetric, isomers occur. The major product is the one where the
hydrogen is removed from the carbon with the most carbon-carbon bonds
Dehydration: Water is formed as a product
H H
H H
R
C C R'
+
OH
-
R
C C R'
+
H2O
+
Cl
-
Cl H
H H
H H
R
C C R'
acid
R
C C R'
+
H2O
H OH
Condensation Reactions

Two molecules combine for form a larger product, eliminating a small molecule such as water or
alcohol
Dehydration: Water is formed as a product, removing an –OH group from one molecule and an H from
the other molecule where the 2 molecules are joined
R
OH
+ R'
H2SO4
OH
R
O
R'
O
O
H3C CH2 C
OH
+
H2N CH3
H3C CH2 C
NH CH3
+
H2O
Esterification: Reaction of a carboxylic acid with an alcohol to form an ester and water
O
O
H3C CH2 C
OH
+
H3C OH
H2SO4

H3C CH2 C
O
CH3
+
H2O
Controlled Oxidation Reactions


Gain of oxygen or loss of hydrogen
(O) tells us that the oxygen is supplied by an oxidizing agent K2Cr2O7 or KMnO4 in the presence of
H2SO4
H OH
H
H O
C C H
+
(O)
H
H H
C C
+
H2O
H H
Note that the aldehyde can also be oxidized further into a carboxylic acid
OH
H3C C
O
CH3
+ (O)
H3C C
CH3
+
H2O
H
Note that the ketone can not be oxidized since there is no H on the C to
make room for a double bond.
OH
H3C C
CH3
+ (O)
NO REACTION
CH3
Hydrolysis


Water molecules are split into H+ and OH- and are used to break down a molecule into smaller
molecules
Sometimes an acid or base can be used instead of water (in cation and anion form)
o When this is done with esters, the sodium salt of the acid that results is soap
o This process is called saponification
O
O
H3C CH2 C
O
CH3
+
+
Na
O
H3C CH2 C
+
OH
-

H3C CH2 C
-
+
O Na
+ H3C
O
O
NH2
+
H2O
H3C CH2 C
OH
+
H2N OH
OH
Reduction


R
Reaction in which carbon atom forms fewer bonds to oxygen atoms or more
[H] indicates a reducing agent, usually LiAlH4 or H2 with a Pt catalyst
+ [H]
C O
R'
H
H
+ HCl
C C
H3C
room
temp
H
Combustion

Among most common oxidation-reduction reactions
Complete Combustion: Excess of oxygen allows reactants to completely react
Hydrocarbon + O2(g)  CO2(g) + H2O(g) + energy
Incomplete Combustion: Occurs when insufficient oxygen is present
Hydrocarbon + O2(g)  C(s) + CO(g) + CO2(g) + H2O(g) + energy