Hydridisation in alkanes and different methods of preparation are discussed.

1. Hybridisation and Method of
Preparation of Alkanes
By
Dr. NIDHI GUPTA
M.M. College of Pharmacy
Mullana, Ambala, Haryana,
India

2. • Alkanes are the simplest class of organic compounds. They are made of
carbon and hydrogen atoms only and contain two types of bonds,
carbon-hydrogen (C—H) and carbon-carbon (C—C) single covalent
bonds. They do not have functional groups.
• Alkanes form a homologous series with the general formula where n is
the number of carbon atoms in the molecule The first member of the
family has the molecular formula CH4, (n = I) and is commonly known as
methane and the second member with molecular formula C2H6, (n=2) is
called ethane.
• These compounds are also known as the Saturated hydrocarbons.
• These hydrocarbons are relatively unreactive under ordinary laboratory
conditions, but they can be forced to undergo reactions by drastic
treatment. It is for this reason that they were named Paraffins (Latin
parum affinis =little activity).
Alkanes

3. SP3 hybridization in alkanes

10. mixing
All 4 unhybridized orbitals Each orbital has "X", "Y" and "Z"-directionality and are 25% s-like and 75% p-like
2s 2px
2nd row valence orbitals
2py 2pz
All 4 sp3-orbitals on the carbon atom The-bonds between carbon and hydrogen
H
H
H
C
H
109°
Molecule is tetrahedral
CH4
H
H
H
C
H
H
H
H
C
H
2s 2px 2py 2pz
Hybridization

14. General methods of preparation of alkanes
1. Hydrogenation of alkenes and alkynes:
Alkanes are formed by passing a mixture of unsaturated hydrocarbon and
hydrogen over finely divided nickel at 200-300°C (Sabatier and Senderens
Reaction). Alkane produced has the same number of carbon atoms as the
original unsaturated hydrocarbon.