• Unsaturated chemical compound
containing at least one carbon-carbon
double bond, where rotation about the
C=C is very difficult.
• To show the presence of the double
bond, the –ane suffix from the alkane
name is changed to –ene.
• Also called olefins( fat dissolving)
• sp2 atomic orbitals
• Trigonal planar, 120o degree
Geometric Isomerism
• Cis-trans isomerism
-isomers that have same order
of atom attachment but a
different arrangement of
their atoms in space.
General Formula
CnH2n
• where n is the number of
carbon atoms in the
molecule
Physical Properties
• Physical state -The first lower
member like ethene, propene and
butene are colorless gases.
• Density - lighter than water.
• Solubility - insoluble in water and
soluble in nonpolar organic solvents.
• more reactive than alkanes due to
their double carbon-carbon bond.
• Boiling point -The boiling points
of alkenes gradually increase with
an increase in the molecular
mass.
• The cis isomer ( example cis-2butene, b.p.= 3.7°C) is higher in
bpt than its trans isomers
(example, trans-2-butene, b.p.=
1°C)
• Melting point
The melting points of alkenes
increase with an increase in
the molecular mass.
Natural Sources
• Isolated from petroleum.
• Plant material like plant
hormone, like Ethylene – a
natural ripening agent and
Terpenes – found in essential oil.
Some Common Alkene Polymers and their Uses
•Ethylene H2C=CH2 Polyethene, Polythene Packaging, cable
insulation, films and sheets
•Tetrafluoroethene F2C=CF2 Polytetrafluoroethene, PTFE,
Teflon Coatings, gaskets.
•Chloroethene (vinyl chloride) H2C=CHCl Polyvinyl chloride,
PVC, Tedlar Insulation, films, pipes
•Styrene H2C=CHC6H5 Polystyrene, Styron Foam for packaging
etc.
•Vinyl acetate H2C=CHOCOCH3 poly(vinyl acetate), PVA
•Paints, adhesives.
Preparations of Alkenes
1. Dehydrohalogenation of Alkyl
halides
2. Dehydration of Alcohol
3. Dehalogenation of Vicinal Halides
4. Reduction of Alkynes
Preparations of alkenes
1. Dehydrohalogenation of alkyl halides
C
H
C
+
KOH
alcohol
C
+
C
KX
+
H2O
Ease of dehy drohalogenation of alky l halides
X
3° > 2° > 1°
Example:
CH3CH2CH2CH2Cl
KOH
CH3 CH2 HC
n-butyl chloride
CH2
1-butene
-
+
KOH is an OH donor use to abstract H
KOH
CH3CH2CHClCH3
sec - buty l chloride
CH3 HC
CHCH3
2 - butene (80%)
+
CH2
CH3CH2HC
1 - butene (20%)
Dehydrohalogenation of Alkyl Halides
• Is an Elimination reaction. The term "elimination"
describes the fact that a small molecule is lost
during the process.
Different mechanisms are possible:
– Loss of the LG to form a carbocation, removal of
H+ and formation of C=C bond
– Simultaneous H+ removal, C=C bond formation
and loss of the LG
– Removal of H+ to form a carbanion, loss of the LG
and formation of C=C bond.
2. Dehydration of alcohol
C
C
H
OH
acid
C
+
C
H2O
alkene
Ease of dehy dration of alcohols
3° > 2° > 1°
ex.
H
H
H
C
C
H
OH
H
H
H2SO4
H
H
C C
H
ethy lene
+
H2 O
ethy l alcohol
+
acid serv es as H donor
H2SO 4
CH3CH2CH2CH2OH
n-butyl alcohol
CH3CH2 HC
OH
CH3
CH3CH2 HC
CH2
1-butene
H2SO4
Al 2O2 in
CH3 HC
CH3 HC
2-butene
(chief product)
CHCH3
+
CH3CH2 HC
heated tube
sec-butyl alcohol
CHCH3
2-butene
(chief product)
1-butene
CH2
Dehydration of Alcohols
• It is the elimination of water
molecule from alcohol to convert
into alkene.
• Lost of H and OH from adjacent
carbons
• An acid catalyst alkene.
Mechanism of Alcohol Dehydration
Step 1 : Alcohol unites with a hydrogen
ion to form the protonated alcohol
Step 2 : Alcohol associates into water
and carbonium ion.
Step 3 : The carbonium ion then loses
a hydrogen ion to form alkene.
3. Dehalogenation of vicinal dihalides
(same side)
C
C
+
Zn
+
C C
ZnX2
X
X
dihalides
Example:
CH3 HC
Br
CH
CH3
Zn
CH3 HC
CHCH3
Br
2,3- Dibromobutane
2- butene
+
ZnX2
4. Reduction of alkynes
R
Pd, NiBr
Lindlar
Cataly st
R
C C
R
C
C
H
sy n (cis)
H
R
R
Na or LiNH3
H
C
H
anti (trans)
C
R
Reduction of Alkynes
• Reducing Alkynes to form trans or cis
Alkenes.
Using Na/ NH3
Step 1:
Sodium transfer an electron to the alkyne
giving a radical anion.
Step 2: The radical anion removes a proton
from the ammonia in an acid/base
reaction
Step 3:
A second atom of sodium transfers
another electron to the alkyne giving an
anion.
Step 4 :
the anion removes proton from the
ammonia in an acid/base reaction.
Reactions of Alkene
•
•
•
•
•
•
•
Halogenation
Hydration
Hydrogenation
Addition of hydrogen Halides
Addition of sulfuric acid
Addition of Carbenes
Addition of Free Radical
•
•
•
•
•
•
•
Allylic Hydrogenation
Dimerazation
Alkylation
Polymerization
Hydroxylation
Halohydrins formation
Ozonolysis
• Hydroborationoxidation
• Epoxidation
Reactions of Alkenes
1. Addition of Halogens (X2)
C
C
+
X2
C
C
X
X
X2 = CL2, Br2
I2 - unreactiv e with alkane
Example.
Br2 CCl4
HCH3C
CH2
propene(propy lene)
CH3CHBrCH2Br
1,2 dibromopropane (propy lene bromide)
Halogenations – Addition of
Halogens
• When an alkene is treated at room temperature
with a solution of bromine or chlorine in carbon
tetrachloride or some other inert solvent, the
halogens adds rapidly to the double bond of the
alkene to give the corresponding vicinal dihalide (
two halogens attached adjacent carbons
2. Addition of Hydrogen (catalytic hydrogenation)
Pt, Pd or Ni
C
C
+
H2
C
C
H
H
Ex.
HCH3C
CH2
propene(propy lene)
H2, Ni
CH3CH2CH3
propane
Hydrogenation of Alkenes
• The relationship between reactants and
products in addition reactions can be
illustrated by the hydrogenation of alkenes
yield alkanes.Hydrogenation is the addition of
H2 to a multiple bond.
3. Addition of hydrogen halides
C
C
+
HX
C
C
H
X
HX = HCL, HBr, HI
Ex.
HCH3C
CH2
HI
CH3CHICH3
2 - iodopropane ( isopropy l halides
propene
Br
no peroxides
HCH3C CH2
H3C
C
CH3
Markov nikov addition.
H
2 - bromopropane
(Isopropy l bromide)
HBr
peroxides
CH3CH2CH2Br
1 - bromopropane
(n - propy l bromide)
anti - Markov nikov addition
Ex.
HCH3C
H3C
CH
H
CH2
CH2
+ HI
+ HI
H3C CH
H3C CHI CH3
I
CH2
actual product
HI
CH2=CHCl
CH3CHICl
-
- -
1 Chloro 1 iodoethane
v iny l chloride
CH3
H3CHC=C
CH3
CH3
+
HI
I
CCH2CH3
CH3
CH3CH=CHCH3
+
HI
CH3CHICH2CH3
Addition of hydrogen halides
– In the addition of an acid to the C=C of an
alkene, the hydrogen of the acid attaches
itself to the carbon that already holds the
greater number of hydrogens
– The reactivity of alkene, with halogen
acids is in the order;.
HI > HBr > HCl
4. Addition of sulfuric acid
C
C
+
H2SO4
C
C
H OSO3H
alky l hy drogen sulf ates
Ex.
HCH3C
propene
CH2
80% H2SO4
OSO3H H2O, heat
H3C CHCH3
H3C CHCH3
OH
Isopropy l alcohol
CH2=CH2
98%H2SO 4
CH3
H2C
CCH3
H2O, heat
CH3CH2OSO 3H
63%H2SO4
CH3CH2OH + H2SO 4
5. Addition of water. HYDRATION
C
C
+
HOH
H
+
C
C
H
OH
Ex.
OH
+
HCH3C
propene
CH2
H2O, H
H3C
H3 C
C
CH2
CH
Isobuty lene 4
H3C
CHCH3
Isopropy l alcohol (2 - propanol)
CH3
+
H2O, H
H3C
C
CH3
OH
tert - buty l alcohol
Addition of Water - Hydration
– When heated with water in the presence of an
acid catalyst, alkenes yield alcohol ROH.
– The process is called hydration of alkenes because
it involves the addition of water across the double
bond.
– The addition of the HOH across the double
bonded carbon that bears the greater number of
hydrogen atoms and the hydroxyl groups goes to
the other double-bonded carbon
6. Halohydrin formation
C
C
+
X2
+ H2O
C
C
H
OH
+ HX
X2 = Cl2, Br2
Ex.
Cl2, H2O
HCH3C CH2
propy lene
(propene)
H3C CH
CH2
HO
Cl
propy lene chlorohy drin
f ollow Markov nikov ru
Sterospecific:
H
H3C
C
CH3
Cl2, H2O
cis - 2 - butene
CH3
threo (stereospecif ic)
CH3
C
OH
H
H
H
H
3 - chloro - 2 - butanol
C
H3C
Cl
CH3
Cl2, H2O
H
Cl
3 - chloro - 2 - butanol
C
H3C
H
trans 2 - butene
OH
H
CH3
ery thro
7. Dimerization (di = two, mer = part, product contains exactly twice
the # of C & H atom as the original).
CH3
H3C C CH2
isobuty lene
CH3
+ H3C
C CH2
isobuty lene
CH3
H2SO 4
CH3
CH3
+
H3C
H3C C CH2 C CH2
CH3
C CH C
CH3
CH3
2,4,4 - trimethy l - 2 - pentene 2,4,4 - trimethy l - 1 - pen
H3 C
Mechanism:
CH3
CH3
H3C
C
CH2
+ H:Br
CH3
CH3
H3C
C
+
CH3
H3C
+ H3C
C
CH2
H3C
C
+
CH3
+
CH3
CH3
C
C
+
H3C
CH2
addition of a hy drogen ion
: Br to isobuty lene to f orm
the carbon
H3C
CH3
CH3
H3C
C
CH
C
CH3
H3C
Addition of the tert-butyl cation to iso butylene; the orientation of addition is
duch to yield the more stable tertiary cation. Step(2) brings about the union
of two : isobutylene units, which is of course necessary for the product.
8. Alkylation
C C
+
R
acid
H
ex.
CH3
H3 C
C
C
C
H
R
CH3
CH2
+
H3 C
C
CH3
H
H2SO4
H3 C
C
CH3
CH2
C
CH3
isobuty lene
CH3
isobutane
H
CH3
2, 2, 4 - trimethy l pentane
mechanism:
CH3
H3 C
C
CH3
+
CH2
H:B
C
C
CH3
+
CH3
CH3
H3C
H3C
CH2
+
H3 C
C
+ :B
CH3
+
H3C
C
+
CH3
CH2
CH3
CH3
H3C
C
+
CH2
C
CH3
CH3
+
H
C
Addition of a
tert-butyl
carbocation to
isobutylene
CH3
CH3
CH3
CH3
Addition of a hydrogen
ion to form carbocation
C
CH3
CH3
CH3
H3C
C
H
CH3
+C
CH3
CH3
CH3
CH2
C
CH3
CH3
+
Carbocation
abstracts a
hydrogen atom with
its pair of electrons
from a molecule of
alkane. This
abstraction of
hydride ion yields
an alkane of 8
carbons and a new
carbocation to
continue the chain.
A carbocation may:
a.) combine with a negative ion or other basic molecule
b.) rearrange to a more stable cabocation
c.) eliminate a hydrogen ion to form an alkene
d.) add to an alkene to form a larger carbocation
e.) abstract a hydride ion from an alkane
9. Oxymercuration - demercuration
oxy mercuration
C
C
+ H2O + Hg(OAc)2
mercuric acetate
C
C
demercuration
NaBH4
HO AcOHg
organomercurial cmpd.
C
HO H
alcohol
Markov nikov orientation
•Oxymercuration – involves addition to the C=C of OH and HgOAc
(mercuric ion)
•Demercuration – the HgOAc is replaced by H
C
Ex.
Undergo the process
of
oxymercuration,
involves addition to
CH(CH2)3CH3 the carbon – carbon
double bond of –OH+
-HgOAc
- hexanol
OH
H3C(H2C)3HC
CH2
Hg(OAc)2, H2O
NaBH4
H3C
1 - hexene
2
CH3
CH2CH3C
CH2
Hg(OAc)2, H2O
CH3
NaBH4
CH3 Follows Markovnikov
addition
CH2CH3C
2 - methy l - 1 - butene
OH
tert - penty l alcohol
CH3
Hg(OAc)2, H2O
CH3
NaBH4
OH
1 - methy lcy clopentanol
1 - methy lcy clopentene
CH3
CH3
H3C
C
CH
CH2
CH3
3, 3 - dy methy l - 1 - butene
Hg(OAc)2, H2O
NaBH4
H3C
C
HC
CH3
CH3
OH
3, 3 - dy methy l - 2 - butanol
10. Hydroboration – oxidation
C
C
+
(BH3)2
C
C
H2O 2
OH
Diborane
H
-
B
C
C
H
OH
Anti - markov nikov orientation
With the reagent Diborane, alkenes undergo hydroboration to yield alkylboranes,
which on oxidation give alcohols.
(BH3)2
diborane
H2C=CH2
CH3CH2BH2
H2C=CH2
(CH3CH2)2BH
(CH3CH2)3B
triethy lboron
-
(CH3CH2)3B
H2C=CH2
+ 3H2O2
OH
3CH3CH2OH
ethanol
+ B(OH)3
boric acid
Mechanism:
C
C
+
H-B
C
C
hy droboration
B
H
B
C
oxidation
C
OH
= H - BH2, H - BHR, H - BR
2
Hydroboration involves the addition of the double bond of BH3 w H becoming
attach to one doubly bonded carbon and boron to the other. The alkylborane can
then undergo oxidation in which the boron is replaced by –OH. Thus, the 2 –
stage reaction process of hydroboration oxidation permits the effect. The addition
to the carbon – carbon double bond of elements of H-OH.
-
H2O2, OH
CH3CH=CH2 (BH3)2
CH3CH2CH2OH
-
n propy l alcohol
propy lene
CH3
H3C
C=CH2
(BH3)2
CH3
-
H2O 2, OH
H3C
Isobuty lene
CH3CH2CH=CH2
-
1 butene
CHCH2OH
Isobuty l alcohol
(BH3)2
-
H2O2, OH
CH3CH2CH2CH2OH
-
n propy l alcohol
11. Addition of free radicals
C
C
+
n - C6H13CH
Y
CH2
peroxides
or light
Z
+
Y
Z
BrCCl3 peroxide
n - C6H13CH
CH2
CCl3
Br
3 - bromo - 1,1,1 - trichlorononane
stability of radical: 3º > 2º > 1º CH
3
CH2
C
bromotrichloromethane
1 - octane
RCH
C
+
CCl4
peroxides
RCH
Cl
CH2
CCl3
Mechanism:
peroxides
rad.
+ Cl:CCl3
.CCl3 + RCH=CH2
RC.H - CH2 - CCl3 + Cl:CCl3
Rad.
+
Rad:Cl
.CCl3
RCH - CH2 - CCl3
RCH - CH2 - CCl3
Cl
+
.CCl3
Electrophilic addition : Markonikov orientation
H3C
CH
CH3
+
2º cation
HBr
HCH3C CH2
propy lene
H3C
CH2
CH2 +
1º cation
H3C
CH
CH3
Br
isopropy l bromide
Free – radical Addition : Anti – Markovnikov orientation
H3C
.
CH
CH2Br
HBr
2º f ree radical
HCH3C CH2
propy lene
Br.
H3C
CH2
.
CH2
Br
1º f ree radical
H3C
CH2
CH2Br
12. Polymerization of Alkenes
Polymerization – the joining together of many small molecules to form very large
molecules.
Monomers – the simple compounds form which polymers are made.
Ex.
nCH2
CH2
O2, heat, pres
H2C
CH2
CH2
CH2
CH2
or
H2C
CH2
poly thy lene
(plastic material of packaging f ilm)
•5 processes of polymerization
1. Free - radical polymerization
2. Cationic polymerization
3. Anionic polymerization
4. Condensation polymerization
5. Coordination polymerization
CH2
Free – radical polymerization
peroxide
nCH2
H2C
CH
CH
CH2
CH2
Cl
Cl
Cl
CH
CH
CH2
Cl
or
H2C
CH2
Cl
n
poly (v iny l chloride)
Polyvinyl chloride - use to make phonograph, records, plastic pipes, when plasticized with
high boiling esters – raincoats, shower curtains and coatings for metal and upholstery fabrics.
Peroxide – initiator, required in small amount in polymerization
-Free radical initiator
Mechanism:
peroxide
Free radical adds to
molecule of alkenes
which for another free
radical
.
rad
decomposition of peroxides to f orm f ree radical
rad
H2C
radCH2
CH
G
.
CH
chain initiating step
G
This radical adds to another
molecule of alkene to generate
another free radical. This radical
adds to another molecule of alkene
to generate a still larger radical
radCH2
.+
CH
G
H2 C
CH
G
radCH2
CH
G
CH2
.
CH
G
chain propagating step
13. Addition of Carbenes. Cycloaddition
carbenes – derivative of methylene
H2C
+
N
N
UV light
photoly sis
diazomethans
H2C
C
ketene
O
CH2
+
N2
methy lene
UV light
+
CH2
CO
methy lene
Methylene exist into 2 different forms
.
:. ..
singlet methylene – unshared electrons are paired, less stable
& generated first in photolysis : stereospecific addition
CH2
:
or
H
C
H
triplet methylene – unshared electrons are not paired,
free radical (diradical) : nonstereospecific addition
H
..
:..
C
H
Cycloaddition: addition of the carbon – carbon double bond
HCH3C
2 - butene
+
CH2N2
CHCH3
diazomethane
light
HCH3C
CHCH3
CH2
1, 2 - dimethy cy clopropan
Sterospecific: (addition of methylene can occur with 2 different kinds of
stereochemistry.)
Photolysis of diazomethane into in liquid
+
cis - 2 -butene
CH2N2
cis 1, 2 - dimethy lcy clopropane
And in liquid
+
trans 2 -butene CH2N2
+ N2
trans 1,2 -dimethy lcy clopropane
CH2
:+
C
C
C
C
CH2
. .+
CH2
C
C
C
CH2
.
.
C
Non – stereospecific: cis/trans2 – butene + CH2N2
C
C
CH2
Singlet methylene
Stereospecific
Electrophilic addition
Electron deficient and
can find electrons at
the C-C double bondingle
C
C
CH2
both cis and trans 1,2 dimethylcyclopropane
Triplet methylene
Non - Stereospecific
Free radical addition
ff. by addition
Methylene undergoes intersection
C
H
+ CH2
C
CH2
H
Addition of substituted carbenes: 1,1 - elimination
- +
HCH2C
2 - butene
CHCH3
+ CHCl3
t - BuO K
chlorof orm
HCH3C
CHCH3
+
t - BuOH
+KCl
C
Cl
Cl
3, 3 - dichloro - 1, 2 - dimethy lcy clopropa
Mechanism:
..-+ ..
..
t - BuO
H CCl3
..
-
CCl3
HCH3C
CH3CH
.
+.
CCl2
..
..
Reaction involves
a divalent carbon
CCl3
t - BuO H
compound, a
derivative of
Cl CCl2
methylene:
dichlorocarbene
dichlorocarbene:
CU2.
Generated in 2
HCH3C
CHCH3 steps, initiated by
attack on
chloroform by the
C
strong base tertbutoxide ion and
Cl
Cl
then adds to the
alkene.
+
+
Because of the presence of halogen atom, the singlet form is the more
stable form of dichlorocarbene and is the one adding to the double bond.
Addition of Carbenes
• Carbenes are intermediates of the general
formula CH2:. The derivatives of methylene
(CH2) are the carbenes.
•
Methylene is formed by the photolysis of
either diazomethane, CH2N2 or ketene,
CH2=C=O.
14. Hydroxylation. Glycol formation
C
C
+ KMnO4 or HCO2OH
C
C
OH OH
Example.
HCH3C CH2
propy lene
cold, dil. KMnO4 or HCO2OH
H3 C
CH CH2
+ 2MnO2
OH OH
1,2 - propanediol (propy lene gly col)
Oxidizing agents that bring about hydroxylation
a. cold alkaline potassium permanganate, KMnO4
b. peroxy acids, such as peroxyformic acid HCO2OH
-
KMnO 4
sy n hy droxy lation
OH
HO
cis 1,2 cy clopentanediol
HCO2OH
OH
+
-
HO
OH
HO
trans 1,2 cy clopentanediol
anti hy droxy lation
15. Halogenation. Allylic substitution ( same mechanism with substitution in alkenes
H C
C C
+
X2
heat
X C
C C
X2 = Cl2, Br2
low conc.
Ex.
HCH3C CH2
propy lene
Cl2, 600º
Cl - CH2CH
CH2
ally l chloride
Br
+
cy chlohexene
NBS
N - bromosuccinimide
3 - bromocy clohexene
-
CH2=CH CH3
-
-
alkene like site of addition
alkane like site of substitution
-
CH2=CH CH3
heteroly tic attack, addition
-
Free radical attack, substitution
Can we direct the attack to just one of these sites? Yes, by our choice of
rxn. Conditions.
Conditions:
1.alkenes undergo substitution by halogen at high temp. or under the influence of
UV light, generally in gas phase.
2.it can also undergo addition of halogen at low temp. in the absence of light and
generally in liquid state(phase).
low T
CCl4 soln
H3C CH
CH2
H3C
CH
CH2
Cl
Cl
1,2 - dichloropropane
Cl2
heteroly tic add'n
propy lene
500 - 600º
gas phase
Cl CH2 CH
CH2
3 - chloro -1 - propane
HCl
f ree radical subs
N – bromosuccinimide a reagent used
for the specific purpose of brominating
alkenes at the allylic position provides
a constant low conc. of bromine.
O
O
C
CH2
C
HBr
+
CH2
CH2
N
Br
Br2
+
CH2
N
H
C
C
O
O
NBS
succinimide
C
H
v iny lic hy drogen: hard to abstract
C
H
C
H ally lic hy drogen: easy to abstract
.
H
Vinylic hydrogen- hydrogens attached to C=C
Alylic hydrogen – hydrogens attached to a carbon atom next to a double bond
Ease of abstraction of hydrogen atoms: Allylic >3º > 2º > 1º > CH4 > Vinylic
Ease of formation of free radicals: allyl > 3º > 2º > 1º > CH3. > vinyl
Example:
CH3(CH2)3CH2CH2CH=CH2
NBS
16. Ozonolysis (Cleavege rxn)
C
C
+
O
O3
ozone
O
O
O O
ozonide
H2O, Zn
+O
C O
aldehy de
C
ketone
Cleavage – a rxn in which the double bond is completely broken and the alkene
molecules converted into 2 smaller molecule.
Reducing agent (Zn) – prevent formation of hydrogen peroxide
will not react with aldehyde and ketone (aldehyde are often
converted to acid, RCOOH for ease of isolation.)
CH3CH2CH=CH2
O3
CH3
H3C C=CH2
O3
H2O, Zn
CH3CH2CHO
H3C
H2O, Zn
H3C C=O
H
+
O CH
+
CH2=O
CH3CH2CH2CHO
H2O, Zn
+
CH3CH2CH2CH=CHCH3
CH3CHO
H
CH2CH3C
O3
H
H
CH2CH3C
C
H
O
+
O
C
CH2CH3
H2O / Zn
O3
aldehy des
3 - hexene
H
CH2CH3C
aldehy des
CH2CH3
H
CH3
O
+
O
C
CH3
H2O / Zn
O3
ketone
Ozonolysis – is a typical means of degradation
CH2CH3C
CH3
C
CH3
2 - methy l - 2 - penten
17. Cleavage with periodate ( cleavage with a diol)
C
C
KMnO 4
cold, dil.
C
C
NaIO4
acids, ketones. CO
2
OH OH
RCOOH are generally obtained instead of aldehydes, RCHO a
terminal ==CH2 group is oxidized to CO2.
Example.
CH3
+
CH3COOH
carboxy lic acid
O
C
CH3
CH3
ketone
KMnO 4
NaIO4
KMnO 4
CH3CH2CH2COOH
NaIO4
carboxy lic acid
carbon dioxide
+
CO2
H3C
CH
C
CH3
2 - methy l - 2 - butene
HCH2CH2CH3C
CH2
Cleavage of cycloalkenes
H2O, Zn
O3
H 2C
di - aldehy de
H 2C
CH2
H2C
CH
H2C
CH
CH2
KMnO 4
NaIO4
CH 2
CHO
CHO
CH 2
CH 2
H2C
COOH
H2C
COOH
CH 2
di - acid
18. Epoxidation of Alkenes
O
C=C +CH3COOH
O
C
C
+ CH3COH
O
Alkene
Peroxyacetic Acid
Epoxide
Carboxylic acid
Example
O
H2C=CH(CH2)9CH3 + CH3COOH
1-Dodecane
Peroxyacetic acid
O
CH2-CH(CH2)9CH3 + CH3COH
1,2-epoxydodecane
Acetic acid