What is the result of substituting an alcohol with a halide ion in the presence of an acid?

The substitution of an alcohol with a halide ion in the presence of an acid leads to the replacement of the hydroxyl (OH) group of the alcohol with a halide ion. This reaction typically occurs under acidic conditions, where the acid protonates the hydroxyl group, making it a better leaving group. Once the hydroxyl group is protonated, it can be replaced by the halide ion, resulting in the formation of an alkyl halide.

This type of reaction is known as nucleophilic substitution, where the halide ion acts as a nucleophile and attacks the carbon that is bonded to the now protonated hydroxyl group. As this occurs, the OH group departs, allowing the halide to bond to the carbon, and thus, effectively substituting the alcohol with a halide.

The other outcomes mentioned in the choices, such as the formation of an ester or the dehydration of the alcohol, do not accurately reflect the main result of the substitution reaction under these specified conditions. While it is true that alcohols can undergo dehydration to form alkenes under certain conditions, such a process does not involve halide ions nor focuses on substituting the OH group. Therefore, the correct description of the reaction occurring in the presence