Isopropyl alcohol (also isopropanol, iso, isopro, rubbing alcohol, or the abbreviation IPA) is a common name for propan-2-ol, a colorless, flammable chemical compound with a strong odor. It has the molecular formula C3H8O and is the simplest example of a secondary alcohol, where the alcohol carbon is attached to two other carbons. It is an isomer of propanol.
Isopropyl alcohol is produced by combining water and propylene.[2] There are two processes for achieving this: indirect hydration via the sulfuric acid process and direct hydration. The former process, which can use low quality propylene, predominates in the USA while the latter process, which requires high-purity propylene, is more commonly used in Europe.
The indirect process reacts propylene with sulfuric acid to form a mixture of sulfate esters. Subsequent hydrolysis of these esters produces isopropyl alcohol. Direct hydration reacts propylene and water, either in gas or liquid phases, at high pressures in the presence of solid or supported acidic catalysts. Both processes require that the isopropyl alcohol be separated from water and other by-products by distillation.
Although isopropanol is sometimes sold as "Isopropyl Rubbing Alcohol, 70% (or 91%)" and "Isopropyl Rubbing Alcohol, 99%", there is no isopropyl alcohol in the United States Pharmacopeia formula for rubbing alcohol, U.S.P.
Isopropyl alcohol is cheaply available. Like acetone, it dissolves a wide range of nonpolar compounds. It is also relatively nontoxic and dries quickly. Thus it is used widely as a solvent and as a cleaning fluid (by dissolving lipophilic contaminants such as oil).
Isopropanol is a major ingredient in "dry-gas" fuel additive. In significant quantities, water is a problem in fuel tanks as it separates from the gasoline and can freeze in the supply lines at cold temperatures. The isopropanol does not remove the water from the gasoline. Rather, the isopropanol solubilizes the water in the gasoline.
Alcohols have applications in industry and science as reagents or solvents. Because of its low toxicity and ability to dissolve non-polar substances, ethanol can be used as a solvent in medical drugs, perfumes, and vegetable essences such as vanilla. In organic synthesis, alcohols serve as versatile intermediates.
Some alcohols, mainly ethanol and methanol, can be used as an Alcohol fuel. Fuel performance can be increased in forced induction internal combustion engines by injecting alcohol into the air intake after the turbocharger or supercharger has pressurized the air. This cools the pressurized air, providing a denser air charge, which allows for more fuel, and therefore more power.
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