Hydrolysis of Halogenoalkanes

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Hydrolysis of Halogenoalkanes

(Planning Section)

The aim of this experiment is to show how the rate of reaction of the halogenoalkanes changes in respect to the C-X bond, where the C is the carbon and the X is the halogen. This will occur through a nucleophilic attack. The halogenoalkanes undergo hydrolysis according to the following equation

CnHn+1X + OH¯ --> CnHn+1OH + X¯

Nucleophilic attacks are a predominant type of chemical attack. It is a type of substitution reaction where a nucleophile breaks the bond between the carbon and in this case the halogen and removes the halogen to get a halide ion. There are 3 main types of nucleophilic reaction; one involves hydrolysis, which is the one being used in this experiment and involves an OH molecule, cyanide ions, which is not being used due to cyanide being extremely dangerous and the final nucleophilic reaction involves ammonia ions. This one is not used because it will just keep substituting the chemicals and you will end up with a huge range of compounds, most, if not all of which will not be needed. These products are called amines and an example of one would be CH3CH2NH2, which is ethylamine.
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The bond enthalpies of the 4 most reactive halogens is as follows


Bond enthalpy (kj mol¯¹)









From this table you can see that bond enthalpy decreases going down the group. This means that the weaker bonds will be more reactive with a nucleophile and the C-Cl bond will be the hardest to break out of the bonds being tested.

My prediction for which bond will react most vigorously with the nucleophile is C-I. This is because it ...

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