Final answer:
The hydroxyl group in alcohols is covalently bonded to a carbon atom, forming part of the molecule, while in alkalis, the OH− group is ionic and contributes to the basicity of the compound. Alcohols are neutral or slightly acidic and interact differently with polar substances as compared to alkalis.
Step-by-step explanation:
The hydroxyl group of an alcohol differs from the hydroxyl group of alkalis in terms of bonding and behavior. In alcohols, the hydroxyl group is bound to a carbon atom in a covalent bond, which forms part of the molecular structure of the organic compound. This hydroxyl group does not dissociate in solution to produce hydroxide ions (OH−), which is a characteristic of basic solutions like those of NaOH or KOH. Instead, alcohols have a hydroxyl functional group attached to an aliphatic carbon, making them neutral or slightly acidic, with the ability to donate or accept a proton in reaction to other substances.
An example of an alcohol is ethyl alcohol (ethanol), a familiar substance as the active ingredient in alcoholic beverages. Alcohols can interact with polar substances like water because of their hydroxyl group, but their solubility is affected by the length of the alkyl chain attached to it. Shorter chains are more hydrophilic while longer chains confer more hydrophobic properties to the molecule.
Furthermore, the reactivity of alcohols is largely concentrated around their hydroxyl group, making their chemical behavior quite distinct from the ionic hydroxide of alkalis. Alcohols undergo reactions such as dehydration and oxidation, which are specific to their molecular structure.