What is the common reagent used for substitution with hydroxide ions (OH) in reactions?

The common reagent used for substitution with hydroxide ions (OH) in reactions is indeed aqueous NaOH. Sodium hydroxide is a strong base that fully dissociates in solution to provide hydroxide ions. In nucleophilic substitution reactions, hydroxide ions can act as nucleophiles, meaning they are able to replace a leaving group on a substrate, such as an alkyl halide.

When OH− ions encounter an appropriate substrate, they can effectively attack the electrophilic carbon, leading to the formation of an alcohol as a product. This process is widely observed in organic chemistry, particularly in the synthesis of alcohols from halogenoalkanes.

Other choices may involve nucleophilic substitution under different conditions but are not as commonly used with hydroxide ions. Aqueous HCl provides hydronium ions and would lead to protonation rather than substitution. Ethanol is a neutral nucleophile that is less reactive than hydroxide ions and would not lead to substitution in most cases. Potassium cyanide acts as a nucleophile as well, but it is specific for certain substrates and is not the standard reagent when hydroxide ions are being considered for substitution reactions. Thus, aqueous NaOH stands out as the primary reagent for substitution involving hydroxide