Ethanol is one of the most important industrial chemical.all alcoholic beverages contain ethanol.the alcohol to be used in industry is subjected to lower exercise duty whereas the alcoholic beverages are subjected to high exercise duty.thus alcohol in industry is prevent its misuse for drinking purposes methanol is added to it.the addition of poisonous materials to make it unfit for drinking for prevention of misuse of alcohol is called denatured of alcohol.
methanol gets oxidised to methanal in reacts rapidly with components of lmcell and protoplasm gets congulated.thus drinking this can be very dangerous.