4.16(b)Writing the equations for carbon–carbon bond cleavage in propane and in 2-methylpropane,we see that a primary ethyl radical is produced by a cleavage of propane whereas a secondaryisopropyl radical is produced by cleavage of 2-methylpropane.A secondary radical is more stable than a primary one, and so carbon–carbon bond cleavageof 2-methylpropane requires less energy than carbon–carbon bond cleavage of propane.(c)Carbon–carbon bond cleavage of 2,2-dimethylpropane gives a tertiary radical.As noted in part (b), a secondary radical is produced on carbon–carbon bond cleavage of2-methylpropane. We therefore expect a lower carbon–carbon bond dissociation energy for2,2-dimethylpropane than for 2-methylpropane, since a tertiary radical is more stable than asecondary one.4.17First write the equation for the overall reaction.The initiation step is dissociation of chlorine to two chlorine atoms.
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