The words ethanol and alcohol are not interchangeable. Put simply, ethanol is the only type of alcohol safe to drink. Ethanol is also called ethyl alcohol or grain alcohol. It is one member of a larger class of molecules called alcohols. All ethanol is alcohol; not all alcohol is ethanol.
Methyl Alcohol and Isopropyl Alcohol
Aside from ethanol, two other types of alcohol commonly seen are methyl alcohol (methanol) and isopropyl alcohol (isopropanol). Methanol is a lab solvent, fuel additive, and antifreeze. Like other types of alcohol, it readily absorbs through skin. But, methanol is dangerously toxic and can cause nervous system and organ damage. Isopropyl alcohol is used as rubbing alcohol and occurs in some hand sanitizer products. It quickly evaporates from skin, producing a cooling sensation. Isopropyl alcohol is not as toxic as methanol, so it’s approved for use on skin. However, isopropyl alcohol is not safe to drink. The initial effects of drinking ethanol, isopropanol, or methanol are similar, but only ethanol is reasonably safe to drink (and then, only if it isn’t denatured or contaminated).
Alcohol Definition and Facts
An alcohol is a chemical compound that has at least one hydroxy group (-OH) attached to a saturated carbon atom. The general chemical formula for an alcohol is CnH2n+1OH . Alcohols are classified depending on how many carbon substituents or hydrogen atoms (denoted by “R” in the formula” are attached to the carbon with the hydroxy group. A primary alcohol is RCH2OH , secondary alcohol is RCH2OH , and tertiary alcohol is R3COH.
Alcohols are polar due to the presence of the hydroxyl group. They are more water-soluble than other hydrocarbon. Ethanol, methanol, and propanol are miscible in water. Due to hydrogen bonding, alcohols tend to have higher boiling points than ethers and related hydrocarbons. Each alcohol has its own characteristic melting point, boiling point, and toxicity. In a lab setting, it’s sometimes okay to substitute one alcohol for another. In food, drinks, and cosmetics, the type of alcohol shouldn’t be substituted.
Hydroxy- vs. -ol Names
The confusion between ethanol and alcohol started early on, because the first alcohol to be studied was ethanol. Initially, the two words were used interchangeably. The term “ethanol” was coined in 1892 by combining the word ethane with the -ol ending. The IUPAC names of molecules where the hydroxyl group has the highest priority contain the -ol suffix. If the hydroxyl group isn’t the highest priority, the chemical name usually has a hydroxy- prefix. Sugars are examples of molecules that contain hydroxyl groups, but aren’t named using the hydroxy- prefix or -ol suffix.
References
- IUPAC (2006). “Alcohols.” Compendium of Chemical Terminology (2nd ed.) (the “Gold Book”). doi:10.1351/goldbook.A00204
- Multhauf, Robert (1966). The Origins of Chemistry. London.