When concentrated sulfuric acid reacts with hexane, a highly exothermic reaction takes place. The sulfuric acid acts as a strong acid and protonates the hexane molecule, leading to the formation of a carbocation intermediate. This carbocation is then attacked by the nucleophilic sulfate ion (HSO4-) present in the sulfuric acid, resulting in the formation of a sulfonated product. The reaction can be represented as follows:

C6H14 (hexane) + H2SO4 (concentrated sulfuric acid) → C6H13SO3H (hexyl hydrogen sulfate) + H2O (water)

The heat generated during the reaction can cause the mixture to boil and release fumes, so caution must be exercised while performing this reaction. The product, hexyl hydrogen sulfate, is a sulfonated derivative of hexane and is typically used as an intermediate in the production of various chemicals and surfactants.