Alkyl halides or haloalkanes are used as reagents in many organic reactions and are generally prepared from alcohols. In an acidic medium such as hydrochloric acid, an SN1 mechanism is used to remove the alcohol group from cyclohexanol, using zinc chloride as a catalyst, to form chlorocyclohexane. The oxygen atom from the alcohol group of cyclohexanol bonds with zinc chloride and donates protons to the hydrogen atom of hydrochloric acid, leaving a negatively charged chloride ion. Zinc chloride is used as a catalyst for the reaction in order to make the oxygen atom a better leaving group. The carbon which attaches the oxygen atom to the cyclohexane donates its protons to the positively charged oxygen atom, thus water and zinc chloride are removed from the cyclohexane and the previously attached carbon is now a carbocation. The negatively charged chloride ion donates its protons to the carbocation forming chlorocyclohexane. The SN1 mechanism is used because the nucleophile, chloride ion, is too weak of a base to remove the proton from the adjacent carbon of the carbocation and it can only attack the carbocation itself, forming chlorocyclohexane.

The yield of the reaction is maximized by heating through reflux, so that the reaction can be done in high temperatures without the worry of reactant-evaporation. Since the reaction is done in a closed, isolated environment, the reactants collide more often with greater force and the yield of the reaction heightens.

The solution is then placed in a separatory funnel so that it divides into the aqueous layer containing concentrated hydrochloric acid and zinc chloride and the organic layer that contains the chlorocyclohexane.

The organic layer is dried with sodium bisulfite to remove traces of acid, unreacted cyclohexanol, and water (Yanza, 2014). Sodium bisulfite is used to dry the product because the presence of water can revert it back to cyclohexanol if the chlorine atom becomes a leaving group thus creating a carbocation and the oxygen atom of water attacks the carbocation, or it can revert it back to cyclohexene is the oxygen atom of water attacks the proton on the adjacent carbon to the carbocation. The removal of water prevents the formation of a nucleophile so that it doesn’t attack the carbocation or the proton of the adjacent carbon.

The aqueous layer has to be drained before adding sodium bisulfite to the organic layer in order to separate the hydrochloric acid and the zinc chloride from the organic layer more efficiently instead of drying out the entire volume of the aqueous layer using sodium bisulfite. Upon the addition of sodium bisulfite, sulfur dioxide is formed.

The qualitative test that can be used to verify the presence of chlorocyclohexane is the alcoholic silver nitrate test because it detects the presence of haloalkanes, acyl halides, and organic ammonium halides. A positive test means the formation of insoluble silver halides. The presence of cyclohexanol can be verified using the chromic acid test, which determines the presence of primary and secondary alcohols, and the Lucas test, which determines the presence of tertiary and secondary alcohols. If the product is positive for both it means that the secondary alcohol is determined in the cyclohexanol. For the chromic acid test, a positive test result is the formation of green precipitate and for the Lucas test, the formation of the secondary phase.