High School

Which of the following is the correct IUPAC rule for naming an alkyl group?
1. The suffix -yl is added to the name of the parent hydrocarbon.
2. The suffix -ane is replaced with the suffix -anyl.
3. The suffix -yl is inserted before the suffix -ane.
4. The suffix -ane is replaced with the suffix -yl.

Answer :

In the field of organic chemistry, naming compounds according to the IUPAC (International Union of Pure and Applied Chemistry) rules is fundamental to ensure clarity and consistency. When referring to alkyl groups, which are essentially fragments of hydrocarbons that have one hydrogen removed, IUPAC provides specific guidelines on how these should be named.

Alkyl groups are named by taking the name of the parent hydrocarbon and replacing the suffix -ane with -yl. This forms the basis for identifying simple substituents derived from alkanes.

Let's break down the process:

  1. Identify the Parent Hydrocarbon: Start with the simple alkane from which the alkyl group is derived. For example, the simplest alkane is methane (CH₄).

  2. Change the Suffix: Replace the suffix -ane in the hydrocarbon name with -yl. So, from methane (CH₄), by removing one hydrogen, you get a methyl group (CH₃-).

Hence, for the question, the correct IUPAC rule for naming an alkyl group is:

  1. The suffix -ane is replaced with the suffix -yl.

This rule applies to longer chain hydrocarbons as well. For example, if you remove a hydrogen from butane (C₄H₁₀), the remaining alkyl group is named butyl (C₄H₉-).

By following this method, you ensure that the naming of organic molecules remains systematic and coherent.