EtOH

EtOH, or ethanol, is a simple, volatile alcohol with the formula C2H5OH (C2H6O). It is a colorless, flammable liquid miscible with water, with a boiling point of 78.37 °C and a density of about 0.789 g/mL at 20 °C. Ethanol is the active ingredient in alcoholic beverages and a widely used industrial solvent.

Commercial ethanol is primarily produced by fermentation of sugars via yeast, yielding ethanol and carbon dioxide. The fermentation broth is distilled and purified; beverage-grade ethanol is typically 4–40% v/v, while fuel and industrial grades undergo additional dehydration. A separate route uses acid-catalyzed hydration of ethylene in the petrochemical industry.

Uses include alcoholic beverages, disinfection, and as a solvent in many products. Ethanol is also a common fuel additive in gasoline blends (for example, E10, E85) and a feedstock for chemical synthesis, producing compounds such as ethyl esters and ethyl acetate. Denatured ethanol is ethanol mixed with additives to render it non-consumable.

Metabolism occurs mainly in the liver, where alcohol dehydrogenase converts ethanol to acetaldehyde, which is further oxidized to acetate by aldehyde dehydrogenase. This generates NADH and affects cellular redox balance. Inhalation or ingestion of large amounts can depress the central nervous system; chronic use is associated with liver disease, cardiovascular problems, pancreatitis, and dependence. Fetal exposure risks birth defects and neurodevelopmental disorders.

Regulation varies by jurisdiction but generally includes labeling, taxation, age restrictions for beverage ethanol, and controls on denatured alcohol. Ethanol production and use raise environmental and energy considerations, including feedstock sustainability and emissions.