The invention relates to the production of High purity n-hexane from low value stream such as raffinate from benzene extraction unit in crude oil refineries employing extractive distillation. The present invention further related to an extractive distillation employing an organic solvent having comparable or same Hansen dispersive force parameter (δd) of that of the key component of to be separated through extractive distillation. The present invention is useful for separating and isolating pure cyclohexane, pure methylcyclopentane and pure iso-heptane along with the pure n-hexane.