An addition reaction is a reaction where two or more molecules combine to form a larger one.

These reactions occur to change the unsaturated compound to saturated compound. In dehydrohalogenation reaction, alkyl halides give alkenes.

Rearrangement gives the structural isomers of the reactant while in substitution reaction one of the groups or atoms is replaced by other group. Therefore, the process of converting alkyl halides into alcohol involves substitution reaction.

Reaction of alkyl halides
Primary alkyl halides -
Secondary alkyl halides -
Tertiary alkyl halides