Although these reactions (right) are slow at room temperature,
they are selfsustaining once triggered because of the large amount
of heat they give off.
With a less electronegative element such as chlorine, the reaction
that occurs is a simple displacement of one or more hydrogens, instead
of destruction of the chain (right).
Chlorination, too, usually results in a mixture of products with
varying degrees of substitution. The different mono- and dichloropropanes
that can result from chlorinating propane are shown behind the buttons.
Trichloropropanes and higher chloro-substitutions also are formed.
The dichloropropanes illustrate again the systematic way of naming
organic compounds. Carbon atoms are numbered consecutively in the
longest straight chain that can be traced through the molecule,
then side chains and substituents are identified according to the
carbon to which they are attached.
The "monster" (bottom button) has the perfectly good
systematic name of 1-bromo-2-chloro-2-methylpropane.