Question

Monohalides on reacting with alcoholic $KOH$ give
(A) Alkanes
(B) Alkenes
(C) Alkynes
(D) Aromatic hydrocarbons

Answer 1

Hint: Monohalides on reacting with alcoholic $KOH$ undergoes elimination reaction. A type of chemical reaction known as an elimination reaction involves the removal of two substituents from a molecule. A metal, an acid, or a base usually catalyses elimination. The elimination reaction is used to convert a saturated compound to unsaturated compound.

Complete Step by Step Answer:
When ethyl chloride is treated with alcoholic $KOH$at a high temperature, then an elimination reaction takes place. The $C{{l}^{-}}$ion from one carbon is removed, forming $KCl$ and ${{H}^{+}}$from its adjacent carbon is removed to form${{H}_{2}}O$.

Hence, Monohalides reacting with alcoholic $KOH$ give alkenes.
Correct Option: (B) Alkenes.

Additional Information: Alkenes are the hydrocarbons containing double bonds. As alkenes are non-polar, so these are insoluble in water, but are soluble in non-polar solvents such as benzene. The boiling point and melting point of alkenes increases with increase in chain length. Alkene is used to produce polymers like polythene for bowls, buckets, bags, and other items.

Note: One of the factors that determine whether we get an elimination reaction or a substitution reaction is the type of solvent. Water favours nucleophilic substitution reactions, whereas alcohol encourages elimination processes, hence the ratio of water to ethanol in the solvent is important. The alcoholic $KOH$ is used to convert alkyl halide to alkene. Whereas, aqueous $KOH$ is used to convert alkyl halide to alcohol.