Nature of Bond:
• Halogens are more electronegative than carbon. Thus halogen atoms have a greater tendency than carbon atoms to attract electron density. Therefore, bonds between carbon and halogen atoms are polar in nature. In the carbon–halogen bond, the carbon atom has a partial positive charge, while the halogen atom has a partial negative charge.
• As the halogen atom becomes less electronegative, from fluorine to iodine, the carbon-halogen bond becomes less polar.
• Reactions between alcohols and concentrated halogen acids produce alkyl halides.
• Tertiary alcohols react with concentrated hydrogen chloride within fraction of time at room temperature to form tertiary alkyl halide.
• Phosphorus tri-halides on reaction with alcohols produces alkyl halides.
• Thionyl chloride on reaction with alcohols produces alkyl halides.
• Alkyl halides can be prepared by reacting alkanes with halogens.
• Markovnikov’s rule can be used to predict the major product of reactions between unsymmetrical alkenes and hydrogen halides.
• Vicinal dihalides can be synthesised from the reaction of alkenes with halogens.
• Alkyl iodides can be produced by halogen exchange.
• Aryl halides can be produced by electrophilic substitution of arenes or by the Sandmeyer reaction.