Halogenoalkanes
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Which halogenoalkanes react fastest under hydrolysis C-Cl, C-Br or C-I ?
Igloo says:
Experiment 10.2b (section 3a) in the Nuffield Students’ Book is designed to enable you to find out which of the halogenoalkanes is hydrolysed at the greatest rate. I assume that you have been able to carry out this experiment for yourself, but perhaps you were unable to obtain any meaningful results.
To answer your question: it is the iodoalkane which turns out to be the one which is the most readily hydrolysed.
The instructions for this experiment finish by asking you to try to relate the reactivity of the halogenoalkanes to their dipole moments and to the strength of the relevant carbon-halogen bonds.
The general theory associated with nucleophilic substitution reactions of the halogenoalkanes is given on the opposite page (page 231), and you should read this carefully first before trying to answer the question associated with the experiment.
Since the iodoalkane is the most reactive towards nucleophilic attack it appears that the relative weakness of the carbon-iodine bond is a more significant factor than the polarity of the C-I bond.
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updated: 25 August 2003
