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Organic Chemistry for Hydrocarbon
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Alkanes
• Hydrocarbon chains where all the bonds between carbons are single bonds
• Name uses the ending –ane• Examples: Methane, Propane, Butane,
Octane, 2-methylpentane
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Prefixes for Carbons
1 Meth 6 Hex
2 Eth 7 Hept
3 Prop 8 Oct
4 But 9 Non
5 Pent 10 Dec
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Physical & Chemical Properties
• Alkanes
• Alkenes
• Alkynes
• Aromatics
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Physical & Chemical Properties
Alkanes & Cycloalkanes
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• Boiling points of unbranched alkanes increase smoothly with number of carbons
Physical Properties of Alkanes and Cycloalkanes
• Melting points increase in an alternating pattern according to whether the number of carbon atoms in the chain is even or odd
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Physical Properties of Alkanes and Cycloalkanes
• Branched chain has higher boiling point than strength chain (in case of number of carbon is equal)
• Alkanes are non-polar molecules, this indicates that alkanes are water-insoluble compounds.
• Alkanes are non-conductive compounds.
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Chemical Properties of Alkanes and Cycloalkanes
1.
Alkanes & cycloalkanes• are well flammable.• no soot from combustion.
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Chemical Properties of Alkanes and Cycloalkanes
Alkanes & cycloalkanes are saturated compounds.
(having only single bonds)
Chemical reactions: Substitution reactions
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Chemical Properties of Alkanes and Cycloalkanes
2. Halogenation is a chemical reaction that
incorporates a halogen atom into a molecule.
More specific descriptions exist that specify the type of halogen:
fluorination, chlorination, bromination, and iodination
CH4 + Cl2 CH3Cl + HCl chlorinationlight
C7H10 + Br2 C7H9Br + HBr brominationlight
*light is a necessary factor to make a reaction*
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Chemical Properties of Alkanes and Cycloalkanes
• Alkanes & Cycloalkanes cannot be reacted and
reduced color of KMnO4.
+ Cl2 Cl-CH2-CH2-CH2-CH2-Cl
light
+ Br2 Br-CH2-CH2-CH2-Br
lightAddition reaction
Unstables alicyclic alkanes: more reacitivity
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Physical & Chemical Properties
Alkenes & Cycloalkenes
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• Boiling points and melting point of alkenes increase with number of carbons.
If no. of carbon is same, alkenes have less boiling point and melting point than alkanes, i.e.,
b.p. of C4H10 >C4H8
• Alkenes are non-water soluble compounds, but can soluble in non-polar solvent i.e. ether, hexane
• Alkenes are non-conductive compounds.
Physical Properties of Alkenes and Cycloalkenes
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Chemical Properties of Alkenes and Cycloalkenes
1. Combustion reaction
2C5H10 +15O2 10CO2 + 10H2O +heat
2. Addition reaction
addition at double bond of carbon atom
2.1 Halogenation – halide addition, not required light
CH2=CH2 + Cl2 Cl-CH2-CH2-Cl
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Chemical Properties of Alkenes and Cycloalkenes
2.2 Hydrogenation – hydrogen addition with Ni or Pt
acted as catalyst, alkanes will be obtained.
Ni
CH3-CH=CH2 + H2 CH3-CH-CH2
H H
2.3 Hydrohalogenation – acid halide addition and alkyl
halide will be obtained
CH2=CH2 + HCl H-CH2-CH2-Cl
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Chemical Properties of Alkenes and Cycloalkenes
2.4 Hydration – water addition with H2SO4 acted as catalyst, alcohols will be obtained.
H2SO4
CH2=CH2 +H2O HO-CH2-CH2-OH
3. Oxidation reactionreact with KMnO4 (Oxidizing agent) in water, glycol will be obtained.
2KMnO4 + 4H2O + CH3-CH=CH-CH3
3CH3-CH-CH-CH3 + 2MnO2 + 2KOH
OH OH
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Physical & Chemical Properties
Alkynes
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• Boiling points and melting point of alkenes increase with number of carbons.
If no. of carbon is same:
boiling point of alkynes > alkanes > alkenes
• Alkynes are non-water soluble compounds, but can soluble in non-polar solvent i.e. ether, hexane
Physical Properties of Alkynes
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Chemical Properties of Alkynes
1. Combustion reaction
2C2H2 +5O2 4CO2 + 2H2O +heat
2. Addition reaction
addition at triple bond of carbon atom
2.1 Halogenation – halide addition, not required light
CHCH + Cl2 Cl-CH=CH-Cl
Cl-CH=CH-Cl + Cl2 Cl-CH-CH-Cl
Cl Cl
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Chemical Properties of Alkynes
2.2 Hydrogenation – hydrogen addition with Ni or Pt
acted as catalyst.
Ni
HCCH + 2H2 CH3-CH3
2.3 Hydrohalogenation – acid halide addition and alkyl
halide will be obtained
CHCH + HCl H-CH=CH-Cl
H-CH=CH-Cl + HCl H-CH-CH-Cl
H Cl
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Chemical Properties of Alkynes
2.4 Hydration – water addition with H2SO4 acted as catalyst, • alcohols will be obtained if reactant is ethyne.
H2SO4 OCHCH +H2O H-CH2-C-H
• Normally, ketones will be obtained.
H2SO4 OCH3-CCH +H2O CH3-C-CH3
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3. Oxidation reactionreact with KMnO4 (Oxidizing agent) in water
• Carboxylic acid and CO2 will be obtained for alkyne with primary carbon
3CHCH + 8KMnO4 + 4H2O 3HCOOH + 3CO2 + 8MnO2 + 8KOH
• Ketone will be obtained for alkyne with secondary carbon
O O
3RCCR + 4KMnO4 +2H2O 3R-C-C-R + 4MnO2 + 4KOH
Chemical Properties of Alkynes
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Physical & Chemical Properties
Aromatic compounds
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• Non-water soluble compounds
• Soluble in non-polar organic solvent i.e. ether
• Low boiling point and melting point
• Individual odor compounds
Physical Properties of Aromatics
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Chemical Properties of Aromatics
2. Substitution reaction
2.1 Halogenation – halide substitute with FeCl3 as catalyst
1. Combustion reaction
+ O2 6CO2 + 3H2O
+ Cl2 FeCl3 Cl
+ HCl
152
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Chemical Properties of Aromatics
2.3 Alkylation
Alkyl group substitute by alkyl halide to hydrogen with
AlCl3 as catalyst
2.2 HydrogenationUnder high pressure and temperature with Ni as catalyst
+ 3H2
+ CH3Br AlCl3 CH3
+ HBr
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Naming of Aromatic compounds
CH3
H3C CH3
CH3
CH3
C2H5
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Naming of Aromatic compounds
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Isomers
Compounds that have the
same molecular formula, but different molecular
structures, are called structural isomers
CH3 CH2 CH2 CH CH3
CH3
CH3 CH2 CH2 CH2 CH2 CH3
C6H14
Isohexane
Hexanestraight chain
Branched chain alkanes
C6H14
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Structural Isomers of Butane, C4H10
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Structure formula Name Melting point (0C)
Boiling point (0C)
State at 250C
Density at 200C (g/cm3)
CH3 CH2 CH2 CH3 n-butane - 138.4 - 0.5 gas 0.578
CH3 CH CH3 isobutane - 159.4 - 11.7 gas 0.549
Isomers
Structure formula
Name Melting point (0C)
Boiling point (0C)
State at 250C
Density at 200C (g/cm3)
CH3 CH2 OH Ethanol -114.1 78.5 liquid 0.785
CH3 O CH3 Dimethyl ether
-138.5 -24 gas 0.661
Differences compounds
Same compounds
CH3
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Isomers
C5H12
C4H8
C3H8O
Dichlorocyclomethane
Trichlorocyclomethane
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Functional compounds
Compound Functional group Name
Ether -O- Alkoxy
Alcohol -OH Hydroxyl
Carboxylic acid -COOH Carboxyl
Ester -COO- Alkoxycarbonyl
Aldehyde -COH Carboxadehyde
Ketone -CO- Carbonyl
Amine -NH2 Amino
Amide -CONH2 Amide
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Functional compounds
Identify the functional group of following compounds
CH3CH2CH2COOH
C3H7OH
HCOH
CH3COOCH2CH3