A chemist would recognise that isopropanol and isopropyl alcohol are simply different names for the same substance (chemical structure CH3-CHOH-CH3). Additionally, they would know that propan-2-ol is the same chemical compound as well.
So why does one chemical compound have three different names?
In chemistry, there are different standards for naming chemicals – also called chemical nomenclature. The most common chemical nomenclature is from the International Union of Pure and Applied Chemistry (IUPAC), a global body whose aim is to standardise not only nomenclature, but also chemical terminology (including the names of new elements in the periodic table), methods for measurement, and atomic weights.
There is also the common naming system for chemical compounds. For simple compounds, we tend to use the common rather than the systematic names, for example, water instead of H2O or dihydrogen monoxide, and methane instead of CH4 or carbane. We use this naming system mainly for very common chemicals rather than the thousands of uncommon compounds which have complex names. In most cases, the common name is not recognised internationally whereas the IUPAC name is. Water translates into French as l’eau, into German as das Wasser, and into Hungarian as víz, for example.
Isopropanol vs. isopropyl alchohol vs. propan-2-ol
In the case of isopropanol, the confusion arises from using a combination of the two different standards for chemical nomenclature – and the different class names within IUPAC nomenclature. Through the history of this chemical compound, its name has essentially been bastardised.
IUPAC nomenclature provides functional class names and substitutive names. The IUPAC functional class name is isopropyl alcohol, and the substitutive name is isopropanol. However, these are both ‘general’ names, since the ‘iso’ prefix is from the common naming system. Under the IUPAC system, the correct name is propan-2-ol, although it is not as commonly used as either isopropyl alcohol or isopropanol.
Read our handy guide for more information on isopropanol/isopropyl alcohol/propan-2-ol.
The blog on chemicals.ie and everything published on it is provided as an information resource only. The blog, its authors and affiliates accept no responsibility for any accident, injury or damage caused in part or directly from following the information provided on this website. We do not recommend using any chemical without first consulting the Material Safety Data Sheet which can be obtained from the manufacturer and following the safety advice and precautions on the product label. If you are in any doubt about health and safety issues please consult the Health & Safety Executive (HSE).