What Is Isopropyl Alcohol?
Isopropyl alcohol is a colorless, combustible liquid known by a variety of names. For instance, in the laboratory it may be labeled isopropanol, isopro, iso, isopropyl or simply by the acronym IPA. It is also sometimes called 2-propanol, likely in reference to being an isomer—one of two or more compounds that have the same formula but a different arrangement of atoms—of an inorganic compound known as propanol. Of course, it is most commonly known as simple rubbing alcohol.
Isopropyl alcohol is classified as a secondary alcohol, meaning that the carbon atom that makes up the alcohol component is bound to two other carbon atoms. As such, it can be reduced by oxidation, which yields the solvent acetone. Although it is made from combining water with propylene, it can be easily separated from its water constituent though a process called salting out. This involves the addition of an organic salt such as sodium chloride.
Medicinal and Other Uses
In addition to providing an outlet for chemical experimentation in the lab, isopropyl alcohol can be found in nearly any home medicine cabinet. In fact, it was once the popular choice for medicinal rubdowns—hence the nickname "rubbing alcohol." When applied to the skin, the water component quickly evaporates, cooling the skin's surface and rapidly reducing body temperature. For this reason, it was once recommended for reducing fever in children. However, since rapid decrease in temperature is now considered detrimental, health care professionals no longer recommend the use of it for this purpose.
Although isopropyl alcohol is commonly used in the home as an antiseptic for cuts and scrapes, it is not a harmless substance. For one thing, it is highly combustible in the presence of high heat or an open flame. It can even explode when exposed to air or light because of the formation of peroxides. It is also now recognized that isopropyl alcohol is readily absorbed through the skin and may have harmful systemic effects. If ingested, it is highly toxic and may even be fatal.
Since isopropyl alcohol is a solvent, it has many uses as a cleaning agent, providing safety precautions are observed. For instance, computer users know its value in removing dirt from hard-to-reach areas, such as between keys on keyboards and on mouse wheels. In fact, since it evaporates almost immediately, there is little risk of shock or damage to electrical components. Isopropyl alcohol also removes stubborn glue residue and dried ink. Music shop owners commonly give new life to used vinyl records by wiping them with a soft cloth moistened with a small amount of the substance.
Isopropyl alcohol is also a component of additives intended to prevent or treat the accumulation of water in fuel lines, such as "dry gas." In fact, it helps to reduce the risk of water freezing in fuel lines. It does this by making soluble water that would otherwise separate from the gasoline and turn to ice during cold weather.
Written by Karyn Maier
