SATURATED HIDROCARBONS ALKANE

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SATURATED HIDROCARBONSALKANE
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• Alkane
• paraffin
• saturated hidrocarbons
• hydrocarbons with only single covalent bonds
  between the carbon atoms

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Definition

• Acyclic branched or unbranched hydrocarbons
  having the general formula CnH2n2 , and
  therefore consisting entirely of hydrogen atoms
  and saturated carbon atoms.
• IUPAC Gold Book

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Sifat

• Sukar bereaksi
• C1 C4 pada tekanan suhu normal fase gas
• C5 C17 pada tekanan suhu normal fase cair
• PC18 pada tekanan suhu normal fase padat
• Mudah larut pada pelarut non polar
• Berat jenis naik dengan penambahan atom C
• Pada alkana rantai lurus ? semakin panjang rantai
  maka titik didih titik leleh semakin tinggi

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Carbon Bonding in Alkane

• Each carbon atom must have 4 bonds (either CH or
  CC bonds),
• and each hydrogen atom must be joined to a carbon
  atom (HC bonds).

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Straight-chain alkanes are sometimes indicated by
the prefix n- (for normal)
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Name Molecular Formula CnH2n2 Structural Formula
Methane CH4 CH4
Ethane C2H6 CH3CH3
Propane C3H8 CH3CH2CH3
Butane C4H10 CH3CH2CH2CH3
Pentane C5H12 CH3CH2CH2CH2CH3
Hexane C6H14 CH3CH2CH2CH2CH2CH3
Heptane C7H16 CH3CH2CH2CH2CH2CH2CH3
Octane C8H18 CH3CH2CH2CH2CH2CH2CH2CH3
Nonane C9H20 CH3CH2CH2CH2CH2CH2CH2CH2CH3
Decane C10H22 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
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Isomerism

• Alkanes with more than three carbon atoms can be
  arranged in a multiple number of ways, forming
  different structural isomers.
• Isomers are compounds that have the same
  molecular formula but different structural
  formulas.
• College Chemistry_ch.21.8_p.529

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Practice 1

• Write structural formulas and
• condensed structural formulas of
• Pentane C5H12
• Hexane C6H14

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Pentane
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Hexane
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Alkyl

• Number of carbons Molecule name
• 1 methyl
• 2 ethyl
• 3 propyl
• 4 butyl
• 5 pentyl/amyl
• 6 hexyl
• 7 heptyl
• 8 octyl
• 9 nonyl
• 10 decyl
• 11 undecyl
• 12 dodecyl

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sec-Butyl

• Isopropyl

Isobutyl
tert-Butyl
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IUPAC Nomenclature Basic Principles (1)

• Select the longest continuous chain of carbon
  atoms as the parent compound, and consider all
  alkyl groups attached to it as side chains that
  have replaced hydrogen atoms of the parents
  hydrocarbon.
• The name of the alkane consists of the name of
  the parent compound prefixed by the names of the
  side-chain alkyl groups attached to it.

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IUPAC Nomenclature Basic Principles (2)

• Number the carbon atoms in the parent carbon
  chain starting from the end closest to the first
  carbon atom that has an alkyl or other group
  substitued for a hydrogen atom.

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IUPAC Nomenclature Basic Principles (3)

• Name each side-chain alkyl group and designate
  its position on the parent carbon chain by a
  number (for example, 2-methyl means a methyl
  group attached to carbon number 2).

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IUPAC Nomenclature Basic Principles (4)

• When the same alkyl-group side chain occurs more
  than once, indicate this by a prefix (di-, tri-,
  tetra-, and si forth) written in front of the
  alkyl-group name (for example, dimethyl indicates
  two methyl groups).
• The numbers indicating the positions of these
  alkyl groups are separated by a comma and
  followed by a hypen and are placed in front of
  the name (for example, 2,3-dimethyl).

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IUPAC Nomenclature Basic Principles (5)

• When several different alkyl groups are attached
  to the parent compound, list them in alphabetical
  order for example, ethyl before methyl in
  3-ethyl-4-methyloctane.
• College Chemistry_ch.21.9_p.533

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Practice 2

• The following names are incorrect. Tell why the
  name is wrong and gave the correct name.
• 3-methylbutane
• 2-ethylbutane
• 2-dimethylpentane
• 3-methyl-5-ethyloctane
• 3,5,5-triethylhexane

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• 3-methylbutane
• CH3 CH2 CH CH3
• CH3
• 2-methylbutane

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• 2-ethylbutane
• CH3 CH2 CH CH3
• CH2
• CH3
• 3-methylpentane

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• 2-dimethylpentane
• CH3
• CH3 CH CH CH2 CH3
• CH3
• 2,2-dimethylpentane

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• 3-methyl-5-ethyloctane
• CH3 CH2 CH CH2 CH CH2 CH2 CH3
• CH3 CH2
• CH3
• 5-ethyl-3-methyloctane

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• 3,5,5-triethylhexane
• CH2
• CH3
• CH3 CH2 CH CH2 C CH3
• CH2 CH2
• CH3 CH3
• 3,5-diethyl-3-methylheptane

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Reaction of Alkane Halogenation

• Halogenation means substitution of halogens for
  hydrogen.
• RH X2 ? RX HX
• X F, Cl, Br, I
• Example
• CH3CH3 Cl2 ? CH3CH2Cl HCl
• chloroethane

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Reaction of Alkane Dehydrogenation

• Dehydrogenation means removal of hydrogen.
• CnH2n2 700 900 oC CnH2n H2
• Example
• CH3CH2CH3 ? CH3CHCH2 H2
• propene

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Reaction of Alkane Cracking

• Cracking means breaking up large molecules to
  form smaller ones.
• Example
• C16H34 ? C8H18 C8H16
• alkane alkane alkene

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Reaction of Alkane Isomerization

• Isomerization means rearrangement of molecular
  structures.
• Example

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Chlorination Products of Methane(1)

• CH4 Cl2 ? CH3Cl
• CH3Cl Cl2 ? CH2Cl2
• CH2Cl2 Cl2 ? CHCl3
• CHCl3 Cl2 ? CCl4 HCl

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Chlorination Products of Methane(2)

• Formula IUPAC name Common name
• CH3Cl Chloromethane Methyl chloryde
• CH2Cl2 Dichloromethane Methylene chloryde
• CHCl3 Trichloromethane Chloroform
• CCl4 Tetrachloromethane Carbon tetrachloride

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Cycloalkane/cycloparaffin/naphtane

• Cycloalkanes are types of alkanes which have one
  or more rings of carbon atoms in the chemical
  structure of their molecules ? struktur
  alisiklik.
• Rumus CnH2n
• Contoh

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• Cyclopropane Cyclobutane
  Cyclopentane Cyclohexane
• C3H6 C4H8 C5H10 C6H12

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Sources of Alkanes
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• The two main sources of alkanes are
• natural gas and petroleum / crude oil.
• Natural gas consists of
• Methane
• Other hydrocarbons
• Hydrogen
• Nitrogen
• Carbon monoxide
• Carbon dioxide
• Hydrogen sulfide (just in some location)

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• Petroleum is formed by the decomposition of
  plants and animals over million of years.
• Composition
• Carbon
• Hydrogen
• Nitrogen
• Oxygen
• Sulfur
• Metals
• Four different types of hydrocarbon molecules
  appear in crude oil
• Paraffins
• Naphthenes
• Aromatics
• Asphaltics

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Fractional Distillation of Crude Oil
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• Crude oil is separated into fractions by
  fractional distillation. The fractions at the top
  of the fractional column have lower boiling
  points than the fractions at the bottom. The
  heavy bottom fractions are often cracked into
  lighter, more useful products. All of the
  fractions are processed further in other refining
  units.

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Octane Rating
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• Octane CH3(CH2)6CH3
• Octane has 18 structural isomers
• Octane (n-octane) 0
• 2-Methylheptane
• 3-Methylheptane
• 4-Methylheptane
• 3-Ethylhexane
• 2,2-Dimethylhexane
• 2,3-Dimethylhexane
• 2,4-Dimethylhexane
• 2,5-Dimethylhexane
• 3,3-Dimethylhexane
• 3,4-Dimethylhexane
• 2-Methyl-3-ethylpentane
• 3-Methyl-3-ethylpentane
• 2,2,3-Trimethylpentane
• 2,2,4-Trimethylpentane (isooctane) 100
• 2,3,3-Trimethylpentane

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• The octane rating was developed by chemist Russel
  Marker at the Ethyl Corporation at 1926. The
  selection of n-heptane as the zero point of the
  scale was due to the availability of very high
  purity n-heptane, not mixed with other isomers of
  heptane or octane, distilled from the resin of
  the Jeffrey Pine. Other sources of heptane
  produced from crude oil contain a mixture of
  different isomers with greatly differing ratings,
  which would not give a precise zero point.
• Higher octane ratings correlate to higher
  activation energies. Activation energy is the
  amount of energy necessary to start a chemical
  reaction. Since higher octane fuels have higher
  activation energies, it is less likely that a
  given compression will cause detonation.

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• The alternative method to boost octane rating and
  minimize engine knocking is too add small amounts
  of an additive to the fuel. One such additive
  commonly used in gasoline was tetraethyllead,
  (C2H5)4Pb.
• The function of tetraethyllead is to prevent the
  premature explosions that constitute knocking.
• Use of tetraetthyllead additives poses a serious
  enviromental hazard. Lead becomes pollutant in
  air, water, and sovent.
• Current additives in anleaded gasoline
• Toluene
• Xylene
• Methyl tert-butyl ether (MTBE)