Cometitive chlorination of hydrocarbons
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Date
1959Author
Nelson, Robert L.
Metadata
Abstract
The reactions of chlorine with hydrogen and hydrocarbons have
been widely studied and it is well established that they are chain re¬
factions involving very long chains. There is general agreement as to
the chain initiating and propagating steps but still considerable di¬
sagreement as to the chain terminating steps. The modern trend in kinetics
has been away from the establishment of mechanism in detail and towards
the determination of Arrhenius parameters for elementary reactions such
as those involved in chain propagation.
Hie present work was aimed at determining accurately the rate
constants for the attack of chlorine atoms on different hydrocarbons
(reaction(1))
Cl + R-H -> R + H-Cl (1)
and on different positions in the same hydrocarbon. This has been
accomplished by employing a competitive technique in which reaction
products are analysed for products characteristic of the initial chlorine
at era attack. Absolute rate constants for each hydrocarbon are then found,
if the absolute value for at least one of the substances studied is known.
In this work the rate constant for the chlorine atom attack on hydrogen,
which is reasonably well established, has been used as the standard value
and all other absolute rate constants are obtained from this.
The activation energies obtained from the rate constants have
been explained in a qualitative manner, while the A factors have been
used to test transition state theory.