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ORGANIC CHEMISTRYCHP2 : HYDROCARBON
Prepared By:ARBANAH MUHAMMAD
CLD 10302
TOPICS COVERED
2.1 Introduction in Process Industry2.2 Natural Gas and Petroleum Resources2.3 Alkanes2.4 Alkenes, Addition Polymerization and The
Chemistry of Rubber 2.5 Alkynes2.6 Chlorinated Alkanes and Geometrical Isomers2.7 Aromatic Hydrocarbon
2.1 Introduction in Process Industry
• Petroleum Refining• Polyolefins• Olefins• Ammonia and Urea
2.2 Natural Gas and Petroleum Resources
Gas Processing Plant
Introduction
Classification of Hydrocarbon
Hydrocarbon
Aliphatic Aromatic
Alkanes Alkenes Alkynes
CycloalkanesCycloalkenes
Saturated Unsaturated
Alkane
1. Alkanes2. Alkanes Nomenclature System3. Structural Isomers4. Cycloalkanes5. Sources of Alkanes and Cycloalkanes6. Synthesis of Alkanes7. Reaction of Alkanes
1. Alkane
• Simplest member of hydrocarbon family
• General formula:• Contains only – C H• Saturated compound • Alkanes are hydrocarbons in
which all of the bonds are single bonds
• Alkanes whose carbon atoms are joined in rings are called cycloalkanes.
Ethane
C CH H
H H
H H22 nnHC
No of C
Molecular Formula
Condensed Formula
Structural Formula
Bond Line Formula
Boiling PointMelting Point
(C)
1 C1H4 -182.5 -161.6
2 C2H6 -183.3 -88.6
3 C3H8 -189.7 -42.1
4 C4H10 -138.7 -0.5
5 C5H12 -129.8 36.1
6 C6H18 -95.3 68.7
7 C7H16 -90.6 98.4
8 C8H18 -56.8 125.7
9 C9H20 -53.5 150.8
10 C10H22 -29.7 174.0
Substituent: Alkyl Groups
Alkyl group is a group which is
derived from unbranched-chain
alkanes by removing 1 H atom
from the end C atom
General formula : CnH2n + 1
Represented by “R” symbol
suffix : - yl e.g: eth-yl
Substituent: Alkyl GroupsNo of C Name Structure
1 Methyl - CH3
2 Ethyl -CH2CH3
3 Propyl
Isopropyl
-CH2CH2CH3
CH3 – CH - CH3
4 Butyl
Sec-butyl
-CH2CH2CH2CH3
C
H
H
H
C
H
H
C
H
C
H
H
H
No of C Name Structure
4 Iso-butyl
Tert-butyl
5 Pentyl CH3(CH2)4CH2-
Iso-pentyl
Neo-pentyl
C
H
H
H
C
CH3
H
C
H
H
C
H
H
H
C
H
CH3
C
H
H
C
H
H
C
H
H
H
C
CH3
CH3
C
H
H
C
H
H
H
C
CH3
C
H
H
H
2. Alkanes Nomenclature System
Step 1) Find the longest continuous carbon chain and use the IUPAC name of the unbranched alkane as the basis.
Step 2) Add name of substituent as a prefix. Use base name with yl ending. Use replicating prefixes (di-, tri-, tetra-, etc.) according to the number of substituents attached to the main chain.
Step 3) Number the chain from the end nearest the substituent, and identify the carbon to which the substituent is attached by number.
Step 4) List substituents in alphabetical order.
Base Name - sufixAlkane
CH2 - methane
C2H6 -ethane
C3H8 -propane
C4H10 -butane
C5H12 -pentane
C6H14 -hexane
C7H16 -heptane
C8H18 -octane
C9H20 - nonane
C10H22 - decane
The proper suffix is
determined by :
i. identifying all the
functional groups
present
ii. Polyfunctional organic
compounds contain
many different kinds of
functional groups.
Then choose the
principal group of
highest priority
HC
HCH3C CH3
CH3CH3
2,3-dimethylbutane
Example
Practice
Exercis
e
Give IUPAC name for the following compound
When 2 or more of different kind of substituents present :
the substituents are listed alphabetically
prefixes di, tri, tert … are ignored
in
alphabetising except iso and
neoCH3 CH CH2
CH3
CH CH2 CH3
CH2
CH3
methylethyl
1 2 3 4 5 6
4-ethyl-2-methyl….
H3C C
CH3
CH3
CH2 CH
CH2
CH3
CH2 CH3
4-ethyl-2,2-dimethylhexane
Example
Practice
Exercis
e
Give IUPAC name for the following compound
Practice
Exercis
e
H3C C
CH3
CH3
CH2 CH
CH2
CH3
CH2 CH3
1 2 3 4 5 6
5
6
6C Continuous C chain :
Substituent :
Prefix :
Suffix :
dimethyl
hex
- ane
& ethyl
4-ethyl-2,2-dimethylhexane
When 2 chains of equal length compete for
selection as parent chain, choose the chain with
the greater number of substituents
H3C CH2
CH3
CH3
CH CH
CH2
CH2
CH CH
CH3CH3
CH3
H3C CH2
CH3
CH3
CH CH
CH2
CH2
CH CH
CH3CH3
CH3
2,3,5-trimethyl-4-propylheptane (4 substituents)
4-sec-butyl-2,3-dimethylheptane (3 substituents)
H3C C
CH3
CH3
CH2 CH2 CH CH3
CH2CH3
5-ethyl-2,2-dimethylheptane
Example
Practice
Exercis
e
Give IUPAC name for the following compound
When first branching occurs at an equal distance
from either end of the longest chain, choose the
name that gives the lower number at the first
point of different
1 2 3 4 5 6
H3C CH CH2 CH
CH3
CH CH3
CH3
CH3
H3C CH CH2 CH
CH3
CH CH3
CH3
CH3
12356 4
2,3,5-trimethylhexane
2,4,5-trimethylhexane
1 2 3 4
6 7
2,2,5-trimethylheptane
Practice
Exercis
e
Give IUPAC name for the following compound
5H3C C
CH3
CH3
CH2 CH2 CH CH3
CH2CH3
7C Continuous C chain :
Substituent :
Locant :
Prefix :
Suffix :
trimethyl
2, 2, 5
hept
- ane
Structural Isomers Alkane
• Compounds with same number of atom and bonds but different arrangement
C4H10
CH2
CH3
H2C
H3C
butane
HC CH3CH3
2-methylpropaneCH3
Number of Constitutionally Isomeric Alkanes
CH4 1 C8H18 18
C2H6 1 C9H20 35
C3H8 1 C10H22 75
C4H10 2 C15H32 4,347
C5H12 3 C20H42 366,319
C6H14 5 C40H82 62,491,178,805,831
C7H16 9 • Number of isomeric alkanes increases as the number of carbons increase.
• There is no simple way to predict how many isomers there are for a particular molecular formula.
Cyclopropane cyclohexane
cyclobutane
cyclopentane
• Cyclic alkane with general formula: CnH2n• Parent name: alkane . Add cylco in front.
Cycloalkanes
If only one substituent present :
not necessary to
designate its position
cyclo
CH3
Example
suffix
prefix
Methyl
16 C
hexane
When 2 substituents present :
i. Numbered the C beginning with
substituent according to the
alphabetical order
ii. Numbered in the way that
gives the next substituent the
lowest number possible
cyclohexane1-ethyl-2-methyl
1-ethyl-6-methylcyclohexaneCH2CH3
CH3
1
23
4
5 6
CH2CH3
CH3
1
23
4
5 6 Ethyl
MethylExample 1
Naming of Cycloalkane
CH2CH3
CH2CH3
H3C CH3
Ethylcyclopentane
3-Ethyl- 1,1-dimethylcyclohexane
Give IUPAC names for the following cycloalkanes :
1,4-dimethylcyclohexane
1-ethyl-3-methylcyclopentane
Isopropylcyclobutane
CH3
CH3
CH3
CH3
CH2CH3
CH3
Practice Exercise
butyl
When single ring is attached to a chain with
greater no. of C atoms :
named as cycloalkylalkane
CH2 CH2 CH2 CH2 CH3
5 C chain
4Cchain
parent
substituent
1 2 3 4 5
1-
cyclo
pentane
When more than 1 ring is attached to a single
chain :
also named as cycloalkylalkane
1,3-
CH2CH2CH2
parent
substituent groups
straight chain
1 2 3
propanehexylcyclodi
Alkane Physical Properties
Non – polar molecules
Not – soluble in water
Low density
Low melting point
Low boiling point
These goes up as the number of carbons increase
Arrange the following compounds in order of
increasing boiling point
CH3CH2CH3
CH3CH2CH2CH2CH3
CH3( CH2)7 CH3
propane
n-pentane
n-nonane
Boiling pointincreases
Practice Exercise
Sources of Alkanes and Cycloalkanes
Crude oil
Refinery gasRefinery gas
C1-C4C1-C4
Light gasoline(bp: 25-95 °C)Light gasoline(bp: 25-95 °C)
C5-C12C5-C12
Naphtha(bp 95-150 °C)
Naphtha(bp 95-150 °C)
Kerosene(bp: 150-230 °C)
Kerosene(bp: 150-230 °C)
C12-C15C12-C15
Gas oil(bp: 230-340 °C)
Gas oil(bp: 230-340 °C)
C15-C25C15-C25
ResidueResidue
• Crackingconverts high molecular weight hydrocarbons to more useful, low molecular weight onesi) thermal cracking (by heat)ii) catalytic cracking (with the aid of catalyst)
• Reforming– increases branching of hydrocarbon chains– branched hydrocarbons have better burning
characteristics for automobile engines
Petroleum Refining
Synthesis of Alkanes
HydrogenationGeneral reaction : Addition
HydrogenationHydrolysisReduction
+ H2C C H C C
H H
H H
H
H
H
H
H
Pt / Pd / Ni
alkene hydrogen alkane
Example:
C2H4 + H2 C2H6
Ni
ethene ethane
Hydrolysis of Grignard reagent (alkylmagnesium halide)
CH3CH2CH2MgCl + H2O CH3CH2CH3 + Mg(OH)ClH+
RMgX + H2O RH + Mg(OH)XH+
alkylmagnesium halide
alkane
Example:
Propylmagnesium chloride
Propane
Wurtz reaction (Reduction of alkyl halide)
2RX + Na R-R + 2NaXalkyl halide reducing
agentalkane
Example:
2CH3CH2CH2Br + 2Na CH3CH2CH2CH2CH2CH3 + 2NaBr
bromopropane hexane
Reaction of alkanes
Combustion
Usage:Fuel
OHCOOalkane 222
CombustionHalogenation
Halogenation
Usage:Dichloromethane: Paint stripper1,2 Dichloroethane: Dry cleaning fluid
Light/heat