IMPORTANT ORGANIC
REACTIONS
Presentation created by S. Schlosz
Information by N. Solomons, K. Dilraj & S. Schlosz
What must you be able to do?
• identify the types of reactions that
hydrocarbons undergo.
• explain what happens during each type
of reaction.
• compare the reactivity of different
hydrocarbons.
Reactions of Alkanes:
H
H
H
C
H
+
Br Br
H
HALOGEN (as found in the
B r Normally
table)
diatomic
B r periodic
+ H
C
H
H
Conditions: Heat OR sunlight; Reactants: alkane + X2 (Br, Cl, I, F)
Process = halogenation; Products = haloalkane + hydrogenFhalide
(F ) Fluorine
NOTE:
F- (Fluoride)
2
This is a hydrogen halide [acid].
Cl- (Chloride)
Cl (Cl2) Chlorine
2C6H14 + 19O2 → 12CO2 + 14H2O
(Br2) Bromine
Alkane + oxygen → carbon dioxide + water +Br
energy
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
H
H
H
H
C
C
C
H
H
H
H
H
+
H
C
H
Conditions: Heat and high pressure OR heat and catalyst
Process = cracking
Products = alkene(s) + alkane(s)
REACTIONS OF
OXIDATION
(COMBUSTION)
ALKANES
Br- (Bromide)
I- (Iodide)
I (I2) Iodine
H
HALIDE (the state of the
Halogen after it has
received
an electron via
SUBSTITUTION
bonding)
Alkane becomes
haloalkane
ELIMINATION
C
H
Alkane becomes alkene(s)
and alkane(s) with shorter
chain
REACTIONS OF ALKENES
NOTE:
Only minor product shown. This is the CIS structure.
The major product will have the TRANS structure [Cl
on opposite sides of the different Carbons]
H
H
H
C
+
C
H
H
Cl Cl
H
C
H
C
Cl
H
H
H
H
C
C
H
H
H
C
+
C
Cl
HBr
H
H
H
H
H
C
C
C
C
H
Br H
H H
M a jo r p ro d u ct
H
Process = halogenation
Product = haloalkane
H
+/
/
H
H
H
H
H
C
C
C
C
H
H
H
Br
H
No water present; Process = hydrohalogenation Product = haloalkane
Major product: H atom attaches to the C atom already having the greater
number of H atoms
NOTE:
This is Markovnikov’s Rule for
ADDITION Reactions.
ADDITION
Alkene becomes alkane, alcohol
or haloalkane
H
H
H
H
H
H
C
C
H
H
NOTE:
The acid must be dilute H2SO4 or H3PO4. Cannot use
HNO3 & HCl as they produce gases.
H
C
+
H
C
+
C
Pt
H
H
H
C
C
H
H
H
C
H
H
H 2O
H
H
H
H
H
C
C
C
C
H H OH H
M a jo r p ro d u ct
H
+
/
H
H
H
H
H
C
C
C
C
H
H
H
OH
150C
H
H
Pt, Pd or Ni as catalyst
Process = hydrogenation; product = alkane
In presence of excess H2O and acid as catalyst
Process = hydration; product = alcohol
Major product: H atom attaches to the C atom already having the greater
number of H atoms
H
Haloalkanes are important compounds that
are used as anesthetics (trichloromethane),
solvents and dry cleaning agents.
Tetrachloroethane
Trichloromethane
(chloroform)
Tetrachloromethane
(Carbon tetrachloride)
H
Halo-ethane
H
H
H
H
H
C
C
C
C
H
Br
H
+
Na OH
heat
H
H
H
H
H
C
H
H
C
C
H
H
H
H
C
C
H
m a jo r p ro d u ct
H
C
Br
H
C
H
+
C
H
H
C
C
H
H
H
H
H + Na OH
H
+ N aB r + H 2O
HaloAlkanes undergo:
H
C
H
C
H
H
heat
H
C
C
H
H
H
H
H
C
C
H
H
H
C
C
C
H
H
H
H
H
/+
C
H
H
+ N aB r + H 2O
ELIMINATION
Haloalkane becomes alkene
m a jo r p ro d u ct
Conditions: concentrated strong base (NaOH, KOH, LiOH), heat
Process = dehydrohalogenation; Products = alkene + NaBr + H2O
Major product: The one where the H atom is removed from the C atom with the least number of
H atoms (most substituted double bond forms i.e. double bond with most alkyl groups forms)
NOTE:
This is VASILY SAYTZEFF’s Rule
for ELIMINATION Reactions.
REACTIONS OF HALOALKANES
H
H
H
H
H
C
C
C
C
H
H
Br
H
H
+
Na OH
H
H
H
H
H
C
C
C
C
H
H
OH
H
H
+
Na Br
Conditions: Dilute strong base (NaOH, KOH, LiOH), mild heat
Substitution - hydrolysis; Products = alcohol + NaBr (KBr or LiBr)
SUBSTITUTION
Haloalkane becomes alcohol
H
H
H
H
H
C
C
C
C
H
H
Br
H
H
+
H 2O
H
H
H
H
H
C
C
C
C
H
H
OH
H
Conditions: Add water, mild heat
Substitution – hydrolysis; Products = alcohol + HBr
H
+
HBr
H
H
C
H
Primary
REACTIONS OF ALCOHOLS
Secondary
Alcohols
Tertiary
/ Alcohols
The O-H group
Alcohols
+
is attached to The O-H group The O-H
group
is attached to
a Carbon
is attached to
a Carbon
which is
a Carbon
is
+
attached to 1 which
which is
other Carbon attached to 2 attached to 3
SUBSTITUTION
ELIMINATION other
other
H H
Carbons
REACTIONS OF ALCOHOLS
Carbons
H
H
H
H
C
C
C
OH H
H
H2SO4
H
H
H
H
C
H
C
C
C
H
H
C
C
C
H
H
H
H
H
+
C
H
H
H
H
m a jo r p ro d u c t
H
+
H 2O
H
Elimination of H2O – dehydration; Products = alkene + H2O
Major product: The one where the H atom is removed from the C atom with
the least number of H atoms (most substituted double bond forms i.e. double bond
H
H
C
C
H
OH
H
To produce gaseous alkenes: pass alcohol over heated AlCl3
H
H
C
C
H
H
H
H
H 2O
C
H
H
Alcohol becomes haloalkane
Alcohol becomes alkene
H– C–C–O–H
H
H
O
H
ESTERIFICATION
H
Acid catalysed condensation
Alcohol + carboxylic acid → ester + water
H2SO4
H
H
H – C– C–C–H
O
H
H – C – CH– C – H
H
H
H
H
C
C
C
C
O
H
H
H
H
H
H
O
+
H
C
C
H
Br
Reactants needed:
Primary & secondary alcohols: NaBr + H2SO4
Tertiary alcohols: HBr (or HCl)
H
C
O
H
H
Substitution with hydrogen halide
Products = haloalkane + H2O
with most alkyl groups)
H
HBr
H
H
H
H
H
C
O
C
H
H
H
H
H
C
C
C
C
H
H
H
H
H C C HH
HO - CH - H
+ H 2O
O
H
H
H
H
+
H 2O