ALKANES(Paraffin)
INTRODUCTION
• Homologous series with general formula CnH2n+2.
• Chief source- mineral oil and petroleum.
• Alkanes belong to a homologous series of organic compounds in
which the members differ by molecular mass of 14.00 atomic
mass unit.
• The only limitation being that the molecule is acyclic, is
saturated and is hydrocarbon.
• Example-Saturated oils (carbon backbone greater than 10) and
waxes.
• Not very reactive, colourless, odourless.
CLASSIFICATION OF CARBON ATOM IN ALKANES (DEPENDING
UPON THE NUMBER OF CARBON ATOMS TO WHICH CARBON ATOM
IN COMPOUND IS BONDED)
• PRIMARY(1°)CARBON ATOM: which is bonded to either no
other carbon atom or 1 carbon atom. For example- methane and
ethane have only primary carbon atom.
• SECONDARY (2°)CARBON ATOM: Bonded to two other carbon
atoms in a compound. For example- in propane C-2 is secondary
in nature.
• TERTIARY (3°)CARBON ATOM: Bonded to other three carbon
atoms. For example- C-2 in iso-butane is tertiary in nature.
• QUATERNARY(4°)CARBON ATOM: Bonded to four carbon
atoms. For example-Neo-pentane.
METHODS OF PREPARATION OF ALKANES:
A:No change in carbon skeleton:
1.Reduction of alkyl halides:
Reduction by dissolving metals: Reduction can be achieved by
dissolving metals like zinc and acetic acid or hydrochloric acid, or
zinc and sodium hydroxide, Zn-Cu couple and ethanol etc.
RX+2H->RH+HX
By reducing agents like LiAlH4,NaBH4 etc.
INTRODUCTION
• Homologous series with general formula CnH2n+2.
• Chief source- mineral oil and petroleum.
• Alkanes belong to a homologous series of organic compounds in
which the members differ by molecular mass of 14.00 atomic
mass unit.
• The only limitation being that the molecule is acyclic, is
saturated and is hydrocarbon.
• Example-Saturated oils (carbon backbone greater than 10) and
waxes.
• Not very reactive, colourless, odourless.
CLASSIFICATION OF CARBON ATOM IN ALKANES (DEPENDING
UPON THE NUMBER OF CARBON ATOMS TO WHICH CARBON ATOM
IN COMPOUND IS BONDED)
• PRIMARY(1°)CARBON ATOM: which is bonded to either no
other carbon atom or 1 carbon atom. For example- methane and
ethane have only primary carbon atom.
• SECONDARY (2°)CARBON ATOM: Bonded to two other carbon
atoms in a compound. For example- in propane C-2 is secondary
in nature.
• TERTIARY (3°)CARBON ATOM: Bonded to other three carbon
atoms. For example- C-2 in iso-butane is tertiary in nature.
• QUATERNARY(4°)CARBON ATOM: Bonded to four carbon
atoms. For example-Neo-pentane.
METHODS OF PREPARATION OF ALKANES:
A:No change in carbon skeleton:
1.Reduction of alkyl halides:
Reduction by dissolving metals: Reduction can be achieved by
dissolving metals like zinc and acetic acid or hydrochloric acid, or
zinc and sodium hydroxide, Zn-Cu couple and ethanol etc.
RX+2H->RH+HX
By reducing agents like LiAlH4,NaBH4 etc.
