In order to allow blending of alcohol with gasoline, the water content of ethanol must be reduced to less than 1% by volume, which is not pos­sible by distillation. Higher water levels can result in phase separation of an alcohol-water mixture from the gasoline phase, which may cause engine malfunction. Removal of water beyond the last 5% is called dehy­dration or drying of ethanol. Azeotropic distillation was previously employed to produce higher-purity ethanol by adding a third component, such as benzene, cyclohexane, or ether, to break the azeotrope and pro­duce dry ethanol [82]. To avoid illegal transfer of ethanol from the indus­trial market into the potable alcohol market, where it is highly regulated and taxed, dry alcohol usually requires the addition of denaturing agents that render it toxic for human consumption; the azeotropic reagents conveniently meet this requirement [82]. Except in the high-purity reagent-grade ethanol market, azeotropic drying has been supplanted by molecular sieve drying technology.