Common Mistakes in Using IUPAC Rules for Naming Polyfunctional Compounds

In chemistry, the IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds. IUPAC stands for International Union of Pure and Applied Chemistry. In general, IUPAC name consists of three parts base, suffix, and substituent.
Most of the students get confused in naming polyfunctional compounds and made mistakes. Following are some of the most common mistakes made by students in using IUPAC rules for naming polyfunctional compounds.

• Not Recognizing the Longest Chain

The longest chain does not have to be that portion of the molecule written horizontally. This is a mistake made by many beginning students.

• Numbering from the Wrong End

When in doubt how to number the chain, do it both ways to pick the name with the lowest substituent group number.

• Failure to Write Prefix

When the same substituents are attached to the same carbon, most of the students fail to write the same number twice.

• Failure to Arrange the Substituent Names in Alphabetic Order

Remember that the structural prefixes such as di-, tri-. tetra-, and neo- are not taken into account when alphabetizing.

• Failure to Write IUPAC NAMES as Single Words

Remember that most of the IUPAC names are written as single words. Exceptions are organic salts and compounds named as acids and acid derivatives.

Many students have a tendency to write names which are derived partially from the IUPAC system and partially from the common /trivial system. For example, 2-propanol is a correct IUPAC name for isopropyl alcohol, the name isopropanol is an objectionable combination of the IUPAC and common names.

Some students made mistakes forgetting to put cyclo - into the names of ring compounds.

• Wrong Selection of the Principal Functional Group in Naming Polyfunctional compounds

This is a mistake made by many students. Always follow the priority order.