organic chemistry chm 207 chapter 3: alkenes nor akmalazura jani
TRANSCRIPT
ORGANIC CHEMISTRY CHM 207
CHAPTER 3:ALKENES
NOR AKMALAZURA JANI
SUBTOPICS
• Naming alkenes and cycloalkenes.
• Physical properties of alkenes:
i) boiling points and densities
ii)polarity
• Preparation of alkenes:
i) dehydration of alcohols
ii) dehydrohalogenation of haloalkanes
• Reactions of alkenes:
i) Addition reaction: a) Catalytic hydrogenation
b) Addition of halogens- In inert solvent
- In water / aqueous medium
c) Addition of hydrogen halides
d) Addition reaction with concentrated sulfuric acid: hydration of alkenes
e) Addition reaction with acidified water (H3O+): hydration of alkenes
ii) Combustion of alkenes
iii) Oxidation:a) epoxidationb)hydroxylationc)Ozonolysis
iv) Polymerization
• Unsaturation tests of alkenes:
i) Reactions of alkenes with KMnO4
ii) Reactions of alkenes with bromine.
• Uses of alkenes:
i) PE
ii) PVC
iii) ethanol
ALKENES
• Also called olefins
• Contain at least one carbon-carbon double bond (C=C)
• General formula, CnH2n (n=2,3,…)
• Classified as unsaturated hydrocarbons (compound with double or triple carbon-carbon bonds that enable them to add hydrogen atoms.
• sp2-hybridized
• For example:
C2H4 - ethyleneCH2 CH2
Naming AlkenesNaming AlkenesNaming AlkenesNaming Alkenes
IUPAC RULES
RULE 1. Select the longest continuous carbon chain that contains a double bond.
This chain contains 6
carbon atoms
RULE 2. Name this compound as you would an alkane, but change –ane to –ene for an alkene.
This chain contains 8
carbon atoms
This is the longest continuous chain. Select it as the parent compound.
Name the parent compound octene.
RULE 3. Number the carbon chain of the parent compound starting with the end nearer to the double bond. Use the smaller of the two numbers on the double-bonded carbon to indicate the position of the double bond. Place this number in front of the alkene name.
IUPAC RULESThis end of the chain is closest to the double bond. Begin numbering here.
The name of the parent compound is 1-octene.
IUPAC RULES
8
7
4 3 2 1
6
5
RULE 4. Branched chains and other groups are treated as in naming alkanes. Name the substituent group, and designate its position on the parent chain with a number.
IUPAC RULESThis is an ethyl group.
8
7
4 3 2 1
6
5
The ethyl group is attached to carbon 4.
4
4-ethyl-1-octene
NEW IUPAC NAMES
• Placing numbers (location of double bond) before the part of the name –ene.
• Example:
CH2 C CH2H
Old naming system: 1-butene New naming system: but-1-ene
1 2 3 4CH3 C C CH2
H H
1 2 3 4CH2 CH35 6
Old naming system: 2-hexene New naming system: hex-2-ene
CH2 C C CH3H H
Old naming system: 3-methyl-1-butene New naming system: 3-methylbut-1-ene
1 2 4CH3
CH3
3
• A compound with more than one double bond.
- Two double bond: diene
- Three double bond: triene
- Four double bond: tetraene
* Numbers are used to specify the locations of the double bonds.
CH2 C C CH2H H
IUPAC names: 1,3-butadiene 1,3,5-heptatrienenew IUPAC names: buta-1,3-diene hepta-1,3,5-triene
1 2 3 4CH3 C C C C C CH2
12347 6 5
H H H H H
1 2
3
476 5
8
IUPAC names: 1,3, 5, 7-cyclooctatetraene new IUPAC names: cycloocta-1,3,5,7-tetraene
ALKENES AS SUBSTITUENTS• Alkenes names as substituents are called alkenyl groups.• Can be named systematically as ethenyl, propenyl, etc. or
by common names such as vinyl, ally, methylene and phenyl groups.
CH2 -CH=CH2
CHCHCH2CHCH2 CH2
CH=CH2
IUPAC name: 3-vinyl-1,5-hexadiene
-CH2-CH=CH2
methylene group(methylidene group)
vinyl group(ethenyl group)
3-methylenecyclohexene
New IUPAC name: 3-vinylhexa-1,5-diene
allyl group(2-propenyl group)
CYCLOALKENES• Contains C=C in the ring
CH3 CH2CH31
23
4
5
6
1
23
4
5
1-methylcyclohexene 1,5-dimethylcyclopentene
12
34
5
6
IUPAC name: 2-ethyl-1,3-cyclohexadieneNew IUPAC name: 2-ethylcyclohexa-1,3-diene
cyclopropene cyclobutene cyclohexenecyclopentene
• Nomenclature of cycloalkenes:- Similar to that alkenes- Number the cycloalkane so that the double bond is between C1 and
C2 and so that the first substituent has as low a number as possible.
* Double bond always between C1 and C2.
NOMENCLATURE OF cis-trans ISOMERS
• cis – two particular atoms (or groups of atoms) are adjacent to each other
• trans – the two atoms (or groups of atoms) are across from each other
C CH3C
H
CH2CH3
H
C CH3C
H
H
CH2CH3
cis-2-pentene trans-2-pentene
PHYSICAL PROPERTIES OF PHYSICAL PROPERTIES OF ALKENESALKENES
Boiling points and densities:
- Most physical properties of alkenes are similar to those alkanes.
- Example: the boiling points of 1-butene, cis-2-butene, trans-2-butene and n-butane are close to 0oC.
- Densities of alkenes: around 0.6 or 0.7 g/cm3.
- Boiling points of alkenes increase smoothly with molecular weight.
- Increased branching leads to greater volatility and lower boiling points.
Polarity:
- relatively nonpolar.
- insoluble in water but soluble in non-polar solvents such as hexane, gasoline, halogenated solvents and ethers.
- slightly more polar than alkanes because:i) electrons in the pi bond is more polarizable (contributing to instantaneous dipole
moments).ii) the vinylic bonds tend to be slightly polar (contributing to a permanent dipole moment).
Alkyl groups are electron donating toward double bond, helping to stabilize it. This donating slightly polarizes the vinylic bond, with small partial positive charge on the alkyl group and a small negative charge on the double bond carbon atom.
For example, propene has a small dipole moment of 0.35 D.
propene, μ = 0.35 D
C C
H3C
H
H
HC C
H3C
H
CH3
H
C C
H3C
H
H
CH3
Vector sum =
propene, μ = 0.33 D
cis-2-butene, bp 4oC
Vector sum = 0
propene, μ = 0
trans-2-butene, bp 1oC
Vinylic bonds
• In a cis-disubstituted alkene, the vector sum of the two dipole moments is directed perpendicular to the double bond.
• In a trans-disubstituted alkene, the two dipole moments tend to cancel out. If an alkene is symmetrically trans-disubstituted, the dipole moment is zero.
Vector sum =
propene, μ = 0.33 D
cis-2-butene, bp 4oC
Vector sum = 0
propene, μ = 0
trans-2-butene, bp 1oC
• Cis- and trans-2-butene have similar van der Waals attractions, but only cis isomer has dipole-dipole attractions.
• Because of its increased intermolecular attractions, cis-2-butene must be heated to a slightly higher temperature (4oC versus 1oC) before it begins to boil.
Vector sum =
propene, μ = 0.33 D
cis-2-butene, bp 4oC
Vector sum = 0
propene, μ = 0
trans-2-butene, bp 1oC
PREPARATION OF ALKENES
Dehydration of alcohols
Dehydrohalogenation of haloalkanes
PREPARATION OF ALKENES
• Alkenes can be prepared in the following ways:
i) Dehydration of alcoholsconc. H2SO4R-CH2-CH2-OH R-CH=CH2 + H2O
ii) Dehydrohalogenation of haloalkanes
NaOH/ethanolR-CH2-CH2-X reflux
R-CH=CH2 + HX
NaOH can be replaced by KOH
• Saytzeff rule:
- A reaction that produces an alkene would favour the formation of an alkene that has the greatest number of substituents attached to the C=C group.
CH3CH2-CH-CH3OH
H+
H+
CH3CH=CH-CH3 + H2O
CH3CH2-CH=CH2 + H2O
2-butanol2-butenemajor product
1-butene
CH3CH-CH-CH2
BrH H
KOH CH3CH=CH-CH3 CH3CH2CH=CH2alcohol
reflux
2-bromobutane2-butene(major product)
1-butene
Dehydration of alcohols
Dehydrohalogenation of haloalkanes
REACTIVITY OF REACTIVITY OF ALKENESALKENES
More reactive than alkanes because:
i) A carbon-carbon double bond consists of a σ and a π bond. It is easy to break the π bond while the σ bond remains intact.
ii) The π electrons in the double bond act as a source of electrons (Lewis base). Alkenes are reactive towards electrophiles which are attracted to the negative charge of the π electrons.
iii) π bond will broken, each carbon atom becomes an active site which can form a new covalent bond with another atom. One π bond is converted into 2 σ bonds.
i) Addition reaction: a) Catalytic hydrogenation
b) Addition of halogens- In inert solvent
- In water / aqueous medium
c) Addition of hydrogen halides
d) Addition reaction with concentrated sulfuric acid: hydration of alkenes
e) Addition reaction with acidified water (H3O+): hydration of alkenes
ii) Combustion of alkenes
iii) Oxidation:a) epoxidationb)hydroxylationc)Ozonolysis
iv) Polymerization
REACTION OF ALKENES
REACTIONS OF ALKENESCatalytic hydrogenation:
- hydrogenation: addition of hydrogen to a double bond and triple bond to yield saturated product.
- alkenes will combine with hydrogen in the present to catalyst to form alkanes.
C C H H C CH H
Pt or Pd
25-90oC
- Plantinum (Pt) and palladium (Pd) – Catalysts
- Pt and Pd: temperature 25-90oC
- Nickel can also used as a catalyst, but a higher temperature of 140oC – 200oC is needed.
H2C CH2 H2
Pt
CH3CH2CH2CH2CH CH2 H2
Pt
H3C CH3
CH3CH2CH2CH2CH2CH3
EXAMPLES:
ethylene ethanelow pressure
low pressurehexene hexane
Addition of halogens:
i) In inert solvent:
- alkenes react with halogens at room temperature and in dark.
- the halogens is usually dissolved in an inert solvent such as dichloromethane (CH2Cl2) and tetrachloromethane (CCl4).
- Iodine will not react with alkenes because it is less reactive than chlorine and bromine.
- Fluorine is very reactive. The reaction will produced explosion.
C C X X C CX X
inert solvent
X X = halogen such as Br2 or Cl2Inert solvent = CCl4 or CH2Cl2
EXAMPLES:
C CHH
H H Br Br
Br2
Br
Br
CCl4
CH3CH=CH2 Cl2CCl4 CH3CH
ClCH2
Cl
C CBr
H H
BrH H
inert solvent (CCl4)
ethene1,2-dibromoethane
* the red-brown colour of the bromine solution will fade and the solution becomes colourless.
cyclohexene 1,2-dibromocyclohexane
propene 1,2-dichloropropane
Addition of halogens:
ii) In water / aqueous medium:
- chlorine dissolves in water to form HCl and chloric (l) acid
(HOCl).
Cl2 (aq) + H2O(l) HCl(aq) + HOCl (aq)
- same as bromine
Br2 (aq) + H2O(l) HBr(aq) + HOBr(aq)
* Reaction of alkenes with halogens in water (eg. chlorine water and bromine water) produced halohydrins (an alcohol with a halogen on the adjacent carbon atom).
EXAMPLES:
CH3CH=CH2 + Br2
H2OCH3 CH
OHCH2Br
CH3 CHBr
CH2Br
1-bromo-2-propanol(major product)
1,2-dibromopropane (minor product)
propene
* Br atom attached to the carbon atom of the double bond which has the greater number of hydrogen atoms.
CH3 CH2
1-chloro-2-butanol1-butene
CH3CH2CH=CH2 CHOH
CH2Cl
Cl2, H2O
Addition of hydrogen halides:
- Addition reaction with electrophilic reagents.
- Alkenes react with hydrogen halides (in gaseous state or in aqueous solution) to form addition products.
- The hydrogen and halogen atoms add across the double bond to form haloalkanes (alkyl halides).
- General equation:
C C C CH X
HX
alkene haloalkane
- Reactivity of hydrogen halides : HF < HCl < HBr < HI
* Reaction with HCl needs a catalyst such as AlCl3
H2C CH2 HClAlCl3
CH3CH2Cl
H-I
CH3CH=CHCH3 + H-Br
I
CH3CH2CHCH3
Br
EXAMPLES:
cyclopentene iodocyclopentane
2-butene 2-bromobutane
MARKOVNIKOV’S RULE
• There are 2 possible products when hydrogen halides react with an unsymmetrical alkene.
• It is because hydrogen halide molecule can add to the C=C bond in two different ways.
C C
H
HCH3
H
H-I
C C
H
HCH3
H
H-I
C C
H
HCH3
H
H I
C C
H
HCH3
H
I H
1-iodopropane
2-iodopropane(major product)
Markovnikov’s rules:Markovnikov’s rules:
- the addition of HX to an unsymmetrical alkene, the hydrogen atom attaches itself to the carbon atom (of the double bond) with the larger number of hydrogen atoms.
Step 2: Rapid reaction with a negative ion. The negative ion (Y-) acts as nucleophile and attacks the
positively charged carbon atom to give product of the addition reaction.
C C
E
Y -C C
E Y
Mechanism of electrophilic addition reactions:- C=C : electron rich part of the alkene molecule- Electrophiles: electron-seeking
Step 1: Formation of carbocation.Attack of the pi bond on the electrophile to form carbocation.
C C C C
E
E Y Y -
carbocation
δ+ δ-
ADDITION OF HYDROGEN HALIDES TO UNSYMMETRICAL ALKENES AND
MARKOVNIKOV’S RULE
CH3CH=CH2 HCl
CH3CHCH2
H Cl
CH3CHCH2
Cl H
1-chloropropane
2-chloropropane(major product)according to Markovnikov's rules
123
Propene
MECHANISM:
Step 1: Formation of carbocation
CC
H H
HCH3H Cl CC
H H
HC
H
H
H
H
CC
H H
HCH
H
H H
or
less stable carbocation
(1o carbocation)
more stable carbocation
(2o carbocation)
Cl-
- 2o carbocation is more stable than 1o carbocation.
- 2o carbocation tends to persist longer, making it more likely to combine with
Cl- ion to form 2-chloromethane (basis of Markovnikov's rule).
CC
H H
HCH
H
H H
Cl-
Step 2: Rapid reaction with a negative ion
CC
H H
HCH
H
H HCl
2-chloromethane (major product)
Addition reaction with concentrated sulfuric acid: hydration of alkenes
- the alkene is absorbed slowly when it passed through concentrated sulfuric acid in the cold (0-15oC).
- involves the addition of H atom and HSO4 group across the carbon-carbon double bond.
- follows Markovnikov’s rule.
C C HHH
H H OSO3H(H2SO4)
CH3CH2OSO3H + H-OH(H2O)
C C H
HH
H
H OSO3H
CH3CH2OH + H2SO4
ethyl hydrogensulphate (CH3CH2HSO4)
When the reaction mixture is added to water and warmed,ethyl hydrogensulphate is readily hydrolysed to ethanol
*ethene reacts with concentrated H2SO4 to form ethanol*
or
*alkene reacts with concentrated H2SO4 to form alcohol*
Addition reaction with acidified water (H3O+): hydration of alkenes
• Hydration: The addition of H atoms and –OH groups from water molecules to a multiple bond.
• Reverse of the dehydration reaction.
• Direct hydration of ethene:
- passing a mixture of ethene and steam over phosphoric (v) acid (H3PO4) absorbed on silica pellets at 300oC and a pressure of 60 atmospheres.
- H3PO4 is a catalyst.
CH2=CH2 H2OH3PO4
CH3CH2OH(g) (g)300 oC, 60 atm
(g)
ethene ethanol
C C H2O C CH OH
alkene alcohol
H+
• Markovnikov’s rule is apply to the addition of a water molecule across the double bond of an unsymmetrical alkene.
• For examples:
CH3 C CH2
CH3
H OH H+
CH3CH=CH2 + H2O CH3CHCH3
OH
CH3 C CH2
CH3
OH H
25oC2-methylpropene
tert-butyl alcohol
propene2-propanol
H+
H+ = catalyst
CC
H H
HCH3
CC
H H
HCH
H
H H
H+
OH
H
CH3CHCH3
O HH
CH3CHCH3
OH
CC
H H
HCH
H
H H
CH3CHCH3
O HH
H+
MECHANISM OF ACID CATALYSED HYDRATION OF ALKENES
Step 1: Protonation to form carbocation
more stable carbocation
(2o carbocation)
Step 2: Addition of H2O to form a protonated alcohol
Step 3: Loss of a proton (deprotonated) to form alcohol
H+ = catalyst
• When HBr is added to an alkene in the absence of peroxides it obey Markovnikov’s rule.
• When HBr (not HCl or HI) reacts with unsymmetrical alkene in the presence of peroxides (compounds containing the O-O group) or oxygen, HBr adds in the opposite direction to that predicted by Markovnikov’s rule.
• The product between propene and HBr under these conditions is 1-bromopropane and not 2-bromopropane.
CH3CH=CH2 HBr CH3CH2CH2Brperoxide
1-bromopropane (major product)anti-Markovnikov's orientation
ANTI-MARKOVNIKOV’S RULE: FREE RADICAL ADDITION OF HYDROGEN BROMIDE
• Anti-Markovnikov’s addition:
- peroxide-catalysed addition of HBr occurs through a free radical addition rather than a polar electrophilic addition.
- also observed for the reaction between HBr and many different alkenes.
- not observed with HF, HCl or HI.
Formation of anti-Markovnikov alcohol
• Alkenes goes to hydroboration reaction to form anti-Markovnikov alcohol.
C C
CH3 C
CH3
CH2
CH3CH=CH2
CH C
CH3
CH3CH3
B2H6
B2H6
B2H6
B2H6
C COHH
CH3 CH
CH3
CH2 OH
CH3CHCH2-OH
CH3CHCHCH3
OH
CH3
H2O2, -OH
anti-markovnikov
examples:
H2O2, -OH
propene propanol
H2O2, -OH
isobutylene isobutyl alcohol
H2O2, -OH
3-methyl-2-butanol2-methyl-2-butene
Combustion of alkenes:
The alkenes are highly flammable and burn readily in air, forming carbon dioxide and water.
For example, ethene burns as follows :
C2H4 + 3O2 → 2CO2 + 2H2O
OXIDATIONOXIDATION• Oxidation: reactions that form carbon-
oxygen bonds.
• Oxidation reaction of alkenes:i) epoxidationii)hydroxylationiii)Ozonolysis
EPOXIDATION OF ALKENES
• Epoxide / oxirane: a three-membered cyclic ether.
CH3 C
O
peroxyacetic acid
O O H C
O
peroxybenzoic acid (PhCO3H)
O O H
m-chloroperoxybenzoic acid (MCPBA)
ClO
OOH
C C R C
O
O O H
O
C C R C
O
OH
alkene peroxyacid epoxide (oxirane) acid
• Examples of epoxidizing reagent:
Examples:
MCPBA
MCPBAO
OCH2CI2, 25oC
cyclohexene 1,2-epoxycyclohexane
CH2CI2, 25oC
cycloheptene 1,2-epoxycycloheptane
• Hydroxylation:
- Converting an alkene to a glycol requires adding a hydroxyl group to each end of the double bond.
• Hydroxylation reagents:
i) Osmium tetroxide (OsO4)
ii)Potassium permanganate (KMnO4)
C C OsO4 H2O2 C C
OHOH(or KMnO4, -OH)
HYDROXYLATION OF ALKENES
glycol
CH CH2CH3
CH2 CH2 CH2 CH2
OH OH
CH2
OH
CHCH3
OH
MnO2
MnO2
KMnO4 (aq), OH-
cold, diluteethene
1,2-ethanediol
KMnO4 (aq), OH-
cold, dilutepropene
1,2-propanediol
* Also known as Baeyer’s test
• Ozonolysis: - The reaction of alkenes with ozone (O3) to form an ozonide, followed by hydrolysis of the ozonide to produce aldehydes and /or ketone.
- Widely used to determine the position of the carbon-carbon double bond.
- Ozonolysis is milder and both ketone and aldehydes can be recovered without further oxidation.
C CR
R
R'
H
O3 CO O
CO R'
H
R
R
(CH3)2SC O
R
RCO
R'
Hozonide ketone aldehyde
or H2O, Zn/H+
OZONOLYSIS OF ALKENES
EXAMPLES:
H
OCH3CH3O
H
H
O
O
OCH3
H
O
CH3O
O
H
O
H
Oi) O3
ii) (CH3)2S3-nonene
i) O3
ii) (CH3)2S
REACTIONS OF ALKENES WITH HOT, ACIDIFIED REACTIONS OF ALKENES WITH HOT, ACIDIFIED KMnOKMnO44
C CR
R''
R'
HC C H
R'R
OH
R''
OH
KMnO4/H+
C OR
R'' COH
R'C O
R
R'' COOH
R'
ketone acid ketone aldehyde
Example:
KMnO4/H+
CO
OC
HO
4-methyl-4-octene 2-pentanone butanoic acid
R CH=CH2KMnO4/H+
R COOH + CO2 + H2O
• Polymer: A large molecule composed of many smaller repeating units (the monomers) bonded together.
• Alkenes serves as monomers for some of the most common polymers such as polyethylene (polyethene), polypropylene, polystyrene, poly(vinyl chloride) and etc.
• Undergo addition polymerization /chain-growth polymer:- a polymer that results from the rapid addition of one molecule at a time to a growing polymer chain, usually with a reactive intermediate (cation, radical or anion) at the growing end of the chain.
POLYMERIZATION OF POLYMERIZATION OF ALKENESALKENES
C C
CI
H
H
H
C C
CI
H
H
H
C C
CI
H
H
H
C C
CI
H
H
H
C
H
H
C
Cl
H
C
H
H
C
Cl
Hn
poly(vinyl chloride)vinyl chloride
repeating unit
SOME OF THE MOST IMPORTANT ADDITION POLYMERS
POLYMER POLYMER USES MONOMER FORMULA
POLYMER REPEATING UNIT
Polyethylene Bottles, bags, films
Polypropylene Plastics, olefin fibers
Polystyrene Plastics, foam insulation
Poly(isobutylene) Specialized rubbers
CH2=CH2 CH2 CH2 n
CH2 CH
CH3
n
C CH
H
CH3
H
CH2 C
CH3
CH3
nC CCH3
CH3
H
H
H2C CH
nC C
H
H H
1) Reactions of alkenes with KMnO4
- KMnO4 is a strong oxidising agent.
- alkenes undergo oxidation reactions with KMnO4 solution under two conditions:
a) Mild oxidation conditions using cold, dilute, alkaline KMnO4 (Baeyer’s test).
b) Vigorous oxidation conditions using hot, acidified KMnO4.
UNSATURATION TESTS FOR UNSATURATION TESTS FOR ALKENESALKENES
a) Reaction of alkenes with cold, dilute, alkaline KMnO4 (Baeyer’s test)
- the purple colour of KMnO4 solution disappears and a cloudy brown colour appears caused by the precipitation of manganese (IV) oxide, MnO2.
- test for carbon-carbon double or triple bonds.
- a diol is formed (containing two hydroxyl groups on adjacent carbon atoms).
C C C C
OH OH
MnO2KMnO4 (aq), OH-
cold, dilute
a diol
2) Reactions of alkenes with bromine
- A solution of bromine in inert solvent (CH2CI2 or CCI4) and dilute bromine water are yellow in colour.
- The solution is decolorised when added to alkenes or organic compounds containing C=C bonds.
C C Br2CH2CI2
C C Br2(aq) H2O
C C
Br Br
C C
OH Br
C C
Br Br
a) Ozonolysis of alkenes:
- For example, ozonolysis of an alkene produces methanal and propanone.
C O
methanal
H
H CO CH3
CH3
propanone
C
H
H C CH3
CH3
CC CH3
CH3H
H
remove the oxygen atoms from the carbonyl compounds and joining the carbon atoms with a double bond.
2-methylpropene
DETERMINATION OF THE POSITION DETERMINATION OF THE POSITION OF THE DOUBLE BONDOF THE DOUBLE BOND
b) Reaction of alkenes with hot, acidified KMnO4
- by using hot, acidified KMnO4, the diol obtained is oxidised further.- cleavage of carbon-carbon bonds occurs and the final products are ketones, carboxylic acids or CO2.
KMnO4/H+
C CH2
CH3
CH3 C O
CH3
CH3 CO2 + H2O2-methylpropene
propanone (ketone)
• Example:
An alkene with the molecular formula C6H12 is oxidised with hot KMnO4 solution. The carboxylic acids, butanoic acid (CH3CH2CH2COOH) and ethanoic acid (CH3COOH), are produced. Identify the structural formula of the alkene.
C C
H
R
H
R'
CH3CH2CH2COOH and CH3COOH
C O
OH
R CO
OH
R'
CH3CH2CH2CH=CHCH3
KMnO4/H+
i) cleavage of the double bond gives a mixture of carboxylic acids
ii) location of the double bond is done by taking away the oxygen atoms from the carboxylic acids and then joining the carbon atoms by the double bond.
RCOOH and R'COOH RCH=CHR'
butanoic acid ethanoic acid 2-hexene
• Ethylene and propylene are the largest-volume industrial organic chemicals.
• Used to synthesis a wide variety of useful compounds.
CH3 C
O
OH
CH2 CH2
CI CICl2
C CH
H
H
H
CH3 C
O
H
O2
C C
CIH
H HCH3 CH2
OH
NaOH
C C
H H
HH
H+
H2O
CH2 CH2
OHOH
OH2C CH2
n
polyethylene
polymerize
acetaldehyde
oxidize
oxidize
acetic acid
ethylene ethylene dichloride
vinyl chloride
H2Ocatalyst
Ag catalystethylene oxide
ethylene glycol ethanol
USES OF ALKENESUSES OF ALKENES
• The most popular plastic.• Uses:
i) Grocery bags ii)Shampoo bottles iii)Children's toy iv)Bullet proof vests v)Film wrappingvi)Kitchenware
POLYETHENE (PE)
POLYVINYL CHLORIDE (PVC)
C CH H
CIH C CH
H
CI
HCH
HCCI
HCH
HCCI
Hnvinyl chloride
polymerize
poly(vinyl chloride)PVC, "vinyl"
USES OF PVC: Clothing
- PVC fabric has a sheen to it and is waterproof. - coats, shoes, jackets, aprons and bags. As the insulation on electric wires. Producing pipes for various municipal and industrial
applications. For examples, for drinking water distribution and wastewater mains.
As a composite for the production of accessories or housings for portable electronics.
uPVC or Rigid PVC is used in the building industry as a low-maintenance material.
Ceiling tiles.
USES OF ETHANOL
• Motor fuel and fuel additive.• As a fuel to power Direct-ethanol fuel cells (DEFC) in order to
produce electricity.• As fuel in bipropellant rocket vehicles.• In alcoholic beverages.• An important industrial ingredient and use as a base chemical
for other organic compounds include ethyl halides, ethyl esters, diethyl ether, acetic acid, ethyl amines and to a lesser extent butadiene.
• Antiseptic use.• An antidote.• Ethanol is easily miscible in water and is a good solvent.
Ethanol is less polar than water and is used in perfumes, paints and tinctures.
• Ethanol is also used in design and sketch art markers.• Ethanol is also found in certain kinds of deodorants.