Question

Name the alkyl radical and functional group for the following organic compound:

${\mathrm{C}}_4{\mathrm{H}}_9\mathrm{COOH}$

Answer 1

Definition of functional group

A functional group is a collection of atoms within molecules that bind together to react in probable ways. Examples of functional groups include the group hydroxyl, ketone, amine, and ether.

Definition of Carboxylic acid group

• Carboxylic group consists of a double-bonded carbon atom linked to an oxygen group and a hydroxyl group through a single bond.
• Their significant characteristics are their acidity.
• The general formula of a carboxylic acid is $\mathrm{R}-\mathrm{COOH}$ , with R referring to the alkyl, alkenyl, aryl, or other groups.

For example,

Name	Formula
Methanoic Acid	$\mathrm{H}-\mathrm{COOH}$
Ethanoic Acid	${\mathrm{CH}}_3-\mathrm{COOH}$

Definition of the alkyl group:

• Functional group that has a carbon and hydrogen atom present in its structure.
• An alkyl substituent is an alkane that is missing one hydrogen.
• The "ane" suffix is replaced by "yl" in naming groups.
• The symbol R is used to designate a generic alkyl group.
• Alkanes can be described by the general formula${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}+2}$. An alkyl group is formed by removing one hydrogen from the alkane chain and is described by the formula${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}+1}$
• $\underset{\mathrm{Methane}}{{\mathrm{CH}}_4}\to \underset{\mathrm{Methyl}}{{{\mathrm{CH}}_3}^{-}}\mathrm{and}\underset{\mathrm{Propane}}{{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_3}\to \underset{\mathrm{Propyl}}{{\mathrm{CH}}_3{\mathrm{CH}}_2{{\mathrm{CH}}_2}^{-}}$

For example,

Alkane name	Alkane formula	Alkyl name	Alkyl formula
Ethane	${\mathrm{C}}_2{\mathrm{H}}_6$	Ethyl	$\underset{\mathrm{Ethane}}{{\mathrm{C}}_2{\mathrm{H}}_6}\to \underset{\mathrm{Ethyl}}{{\mathrm{C}}_2{{\mathrm{H}}_5}^{-}}$
Butane	${\mathrm{C}}_4{\mathrm{H}}_{10}$	Butyl	$\underset{\mathrm{Butane}}{{\mathrm{C}}_4{\mathrm{H}}_{10}}\to \underset{\mathrm{Butyl}}{{\mathrm{C}}_4{{\mathrm{H}}_9}^{-}}$

$\therefore {\mathrm{C}}_4{\mathrm{H}}_9\mathrm{COOH}$ has functional group as carboxylic acid and the alkyl group as butyl, but the number of carbon in total is 5 so the name will be Butane -1- carboxylic acid which is also known as Pentanoic acid.