Sulphonation : - replacement of hydrogen atom of alkane by – SO 3 H group .
CH3
CH CH3
CH3
isobutane
The reaction occurs as : HO-SO3 oleum
450 0 C Homolytic fission
CH3
C
CH3
SO3H
CH3
tert butyl sulphonic acid
HO o + o SO3H
Aromatization : -
RH + 0 OH R o + o SO2H
H3C ( CH2 ) 3CH3 n-Pentane
H3C ( CH2 ) 4CH3 Hexane
AlCl3 / HCl
Cr2O3
773 K 10-20 atm
R o + HOH RSO2H CH3
H3CCHCH2CH3 2-Methyl butane
Benzene
This method is also called dehydrogenation or hydroforming similarly , heptane gives toluene , n-Octane give o-xylene and 2 , methyl heptane give m-xylene .
Thermal decomposition or Pyrolysis or cracking or Fragmentation : - when higher alkanes are heated at high temp ( about 700-800k ) in the presence of alumina or silica catalysts , the alkanes break down to lower alkanes and alkenes .
CH3-CH2-CH3
CH3-CH-CH2 + CH3-CH3 + C2H4 + CH4
Action of steam : - catalyst : nickel , alumina Al2O3
CH4 + H2O ( Steam )
CO + 3H2
This reaction is used for the industrial preparation of hydrogen from natural gas . 8 . Isomerization : -