The Analytical Differences Between Isopropanol and Ethanol

Isopropanol and ethanol are both alcohols with different chemical structures. Isopropanol is also known as isopropyl alcohol (IPA) whereas ethanol is known as ethyl alcohol (EtOH). Since the atoms contained in both alcohols are the same, they have some similar characteristics, but as the chemical structure is different, they have many different features.

Chemical Structure

• Isopropanol is a slightly larger molecule than ethanol. Isopropanol is C3H8O whereas ethanol is C2H6O. That means though both contain the same atoms -- carbon, hydrogen and oxygen -- their properties are different, based on the difference in the number of atoms.

Uses

• Both isopropanol and ethanol have antiseptic properties. Although both can be used to treat wounds, isopropanol is more effective as a skin antiseptic cleanser. The Food and Drug Administration (FDA) found that ethanol used in concentrations from 60 to 95 percent and isopropanol used in concentrations from 70 to 91 percent are safe and effective for the preparation of skin for surgery and for health-care workers washing their hands. Isopropanol is used as a solvent in a wide variety of applications, such as a coating and dye solvent, a cleaning and drying agent and a solvent in pharmaceutical products and cosmetics. Isopropanol is not meant for human consumption whereas ethanol can be used for human consumption if it is pure. Ethanol prepared by yeast is used in the form of whiskey, beer and wine. Ethanol is also used as a car fuel, which is pure alcohol. For human consumption, normally 40 percent alcohol and 60 percent water are mixed with it. When it is used as a car fuel, it gets distilled to make sure it is highly pure. It is also used as a biodiesel fuel in lighting and heating systems.

Effects

• Isopropanol and ethanol have negative effects if consumed in high doses, but isopropanol is about twice as toxic as ethanol. Isopropanol exhibits the symptoms of consumption immediately, within 30 minutes. Common symptoms include vomiting, headache, pain, diarrhea and lack of coordination. It might even lead to death if taken in large quantities. The negative effects of ethanol appear a few hours after consumption. Consumption of ethanol does not usually result in coma or death as in the case of isopropanol.

Denatured Alcohol and Rubbing Alcohol

• Denatured alcohol is a form of ethanol. Since pure ethanol can be consumed, denatured alcohol is made unfit for drinking by adding poisonous and foul-tasting chemicals. Commonly added chemicals include methanol, isopropanol or gasoline.

  Rubbing alcohol is a form of isopropanol. Normally, 70 percent isopropanol and 30 percent water are mixed to form rubbing alcohol. Sometimes, ethanol with added isopropanol is used as rubbing alcohol.