organic chemistry for hydrocarbon

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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

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Alkanes & cycloalkanes• are well flammable.• no soot from combustion.

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Alkanes & cycloalkanes are saturated compounds.(having only single bonds)

Chemical reactions: Substitution reactions

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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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• Alkanes & Cycloalkanes cannot be reacted and reduced color of KMnO4.

+ Cl2 Cl-CH2-CH2-CH2-CH2-Cl

light+ Br2 Br-CH2-CH2-CH2-Br

light Addition reaction

Unstables alicyclic alkanes: more reacitivity

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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 reaction2C5H10 +15O2 10CO2 + 10H2O +heat

2. Addition reactionaddition at double bond of carbon atom2.1 Halogenation – halide addition, not required light

CH2=CH2 + Cl2 Cl-CH2-CH2-Cl

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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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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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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 reaction2C2H2 +5O2 4CO2 + 2H2O +heat

2. Addition reactionaddition at triple bond of carbon atom2.1 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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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-ClH-CH=CH-Cl + HCl H-CH-CH-Cl

H Cl

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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 O3RCCR + 4KMnO4 +2H2O 3R-C-C-R + 4MnO2 + 4KOH


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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 reaction2.1 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 AlkylationAlkyl 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

organic chemistry for hydrocarbon

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