Halogenoalkanes, especially chlorofluorocarbons (CFCs) and other halogenated compounds, have been a significant environmental concern due to their role in ozone layer depletion. When these compounds are released into the atmosphere, they rise and get broken down by UV radiation, releasing halogen atoms. These atoms can catalytically destroy ozone in the stratosphere, leading to the thinning of the ozone layer, which protects Earth from harmful UV radiation. This has led to international agreements like the Montreal Protocol to phase out the production and use of many halogenoalkanes.

Halogenoalkanes can be synthesised from alcohols using halogen acids or phosphorus halides. When alcohol reacts with hydrochloric acid (HCl) in the presence of zinc chloride (a Lewis acid), a chloroalkane is formed. Alternatively, phosphorus halides like phosphorus trichloride (PCl₃) or phosphorus tribromide (PBr₃) can also be used to convert alcohols into the corresponding halogenoalkanes. The choice of reagent often depends on the desired halogen in the final halogenoalkane product.

Tertiary halogenoalkanes tend to undergo elimination reactions more readily than substitution because of steric hindrance. Due to the presence of three bulky alkyl groups attached to the carbon bonded to the halogen, it becomes difficult for a nucleophile to approach and attack this carbon directly. Instead, the base/nucleophile more easily abstracts a proton from a neighbouring carbon, leading to the formation of an alkene (elimination product). This process is favoured over the direct substitution mechanism, especially in polar aprotic solvents and under strong base conditions.

Some halogenoalkanes are chiral because they possess a carbon atom bonded to four different groups or atoms, creating an asymmetric or chiral centre. Due to this asymmetric carbon, these halogenoalkanes can exist in non-superimposable mirror image forms known as enantiomers. Enantiomers have identical physical and chemical properties, except for their behaviour towards plane-polarised light; one enantiomer rotates plane-polarised light clockwise (dextrorotatory), while the other rotates it counterclockwise (levorotatory). The presence of chiral centres in halogenoalkanes and other organic compounds is of particular importance in pharmaceuticals, as different enantiomers can have different biological activities.

Chloroalkanes are generally less reactive in nucleophilic substitution reactions compared to bromoalkanes or iodoalkanes due to the strength of the carbon-halogen bond. The C-Cl bond is shorter and stronger than the C-Br or C-I bond because chlorine is smaller in size compared to bromine and iodine. A shorter and stronger bond is harder for a nucleophile to break, making chloroalkanes less susceptible to nucleophilic attack. On the other hand, the C-Br and C-I bonds are comparatively longer and weaker, making bromoalkanes and iodoalkanes more reactive in nucleophilic substitution reactions.