Nomenclature of Carboxyl Group

Carboxylic acids are a common type of substance that we use every day. Citric acid, a carboxylic acid, is responsible for the sourness of lemons. Vinegar, which is nothing more than a carboxylic acid known as ethanoic acid, is one of the most commonly found preservatives in-home objects. We need to understand how to name these common acids and the laws that go with them.

Formic acid, which is found in ant and wasp stings, causes our bodies to burn. But did you know that formic acid and methanoic acid are two different names for the same thing? Methanoic acid is called Formic acid because the Latin word for ant is ‘Formica’. It was first isolated by distilling ant corpses. Vinegar, commonly known as acetic acid or ethanoic acid, is a common kitchen preservative. What’s the story behind the name vinegar? In this article, we will learn about the Carboxyl Group.

Carboxyl Group

It’s an important class of organic chemicals. A carboxyl group is a functional group with a carbonyl and hydroxyl group linked to a carbon atom by a single bond. A carboxylic acid, on the other hand, is an organic substance having a carboxyl group. Just to remember, A carbonyl group is a carbon double-bonded to oxygen, and an OH group is an OH group.

R-C(O)OH is the class’s general formula. In this formula, R is the alkyl or aryl group. Natural sources of carboxylic acids abound. The majority of this group’s members, however, are synthetically created. 

Carboxylic acid

Carboxylic acids are compounds that have a carbon atom bonded to the functional group COOH (carboxyl group). The attachment of a hydroxyl group to a carbonyl group, however, can result in the production of a carboxyl group, hence the name “carboxyl group.” 

Based on the group present, carboxylic acids can be classified as aliphatic or aromatic. If there is an alkyl group (RCOOH) and If there is an aryl group (ArCOOH). Fatty acids are the C12-C18 members of the aliphatic carboxylic acids. Natural fats or glycerol esters are what you’ll find in nature. Furthermore, esters, acid chlorides, anhydrides, amides, and other essential organic molecules start with this group.

Carboxylic acid is found in a wide range of natural products. For example, formic acid can be found in insect stings, butyric acid in butter, carbonic acid in the bicarbonate system of blood and tissues, the lauric acid in coconut oil, palmitic acid in palm oil, arachidic acid in peanut oil, and stearic acid in chocolate, waxes, soaps, and oils. In this article, we’ll look at how the carboxyl group’s characteristics and structure influence the properties of carboxylic acid molecules.

Examples of Carboxylic acid

• A carboxylic acid is one of the most well-known carbon-based carboxyl group examples. Amino acids and acetic acids, which are utilized to create proteins, contain carboxylic acids.
• The molecule is most usually found as a carboxylate anion R-COO-, because the hydrogen ion detaches off so easily. The anion is given its name due to the suffix “-ate.” An acetate ion is formed when acetic acid (a carboxylic acid) is converted.

Nomenclature of Carboxylic Acid 

One of the first organic compounds to be isolated from nature belongs to this class. As a result, several compounds in this class have more common names. 

Common Names 

• Many of the carboxylic acid group’s common names are derived from their natural sources’ Latin or Greek names. The suffix –ic acid is commonly used in common names. HCOOH is formic acid, for example. 
• The word “formica” means “ant” in Latin. Red ants are the primary source of formic acid. The Latin term “acetum” refers to vinegar, which is a source of acetic acid (CH₃COOH). Butyric acid, which is referred to in Latin as butyrum, is also found in rancid butter.

IUPAC Names

By replacing the “e” of the respective alkane with –oic acid, the IUPAC system makes naming aliphatic carboxylic acids simple. In a carboxylic acid, the carboxylic carbon is the first carbon atom to be numbered. As a result, the first carbon in the parent chain will always be carboxylic carbon.

If a molecule has more than one carboxyl group, it is critical to number the alkyl chain. By adding the multiplicative prefix to the name of the parent alkyl chain, such as dicarboxylic acid, tricarboxylic acid, and so on, you may determine the number of carboxylic acids contained in the chemical. In order to specify the position of –COOH groups in a given compound, the Arabic numerals must be written before the multiplicative prefix.

Methanoic acid, ethanoic acid, propanoic acid, butanoic acid, and other simple members of this family of substances have names like these: Aromatic carboxylic acids, on the other hand, do not always have a uniform nomenclature. They even have a unique IUPAC-approved nomenclature like benzoic acid. The compounds can alternatively be named according to their position and alphabetical order in relation to the main compound.

2-Chloro-3methylbutanoic Acid

When a chemical has multiple functional groups, the carboxyl group is used instead of the other functional groups in the nomenclature. Carboxylic groups are valued more highly than other functional groups.

Instead of alcohol, the molecule in the following example is known as carboxylic acid.

4-Hydroxy-2-methylbutanoic acid

We already know that when naming a chemical, the carboxyl carbon atom is always carbon-1. As a result, while designating the carboxyl group, we don’t need to use a locant.

Carboxylic Acid Naming

These designations are given by chemists to describe the compound’s source of formation. The source name of the compound is suffixed with –ic. The following are a few of these chemicals:

Formula	Common Name	IUPAC Name
HCOOH	Formic acid	Methanoic acid
CH3COOH	Acetic acid	Ethanoic acid
CH3CH2COOH	Propionic acid	Propanoic acid
CH3(CH2)2COOH	Butyric acid	Butanoic acid
CH3(CH2)3COOH	Valeric acid	Pentanoic acid
CH3(CH2)4COOH	Caproic acid	Hexanoic acid
CH3(CH2)5COOH	Enanthic acid	Heptanoic acid

Structure of Carboxylic acid

A functional organic compound is a carboxyl group. A carbon atom is joined to an oxygen atom by a double bond in this carboxyl group structure. It also has a single hydroxyl group with which it is bonded. Carboxylic acids are carboxylated compounds. Many organic acids, such as acetic acid and amino acid, fall under this category.

Structure of Carboxylic acid

On the sides of the molecules, the carboxyl group is usually present. The H atom contained in the hydroxyl group portion ionizes and is released as a free H⁺ ion or proton by the carboxyl group. The rest of the component, which is O, has a negative charge on it. The charge flows forward and backward in the space between the two oxygen molecules, keeping the ionization state stable.

Carboxyl group

Resonance Structure

Carboxylic acids have all of the bonds in the carboxyl carbon in one plane. Carboxyl carbon bonds have an angle of about 120 degrees. The carboxyl carbon is less electrophilic than carbonyl carbon because of its resonance structure. 

Sample Questions

Question 1: What is a carboxylic acid’s proper name?

Answer:

The parent chain in IUPAC nomenclature is the carbon chain with the longest carboxylic group. The carboxyl group occupies the lowest position (always 1) among the other functional groups, and is numbered appropriately. These functional groups, whose names are listed alphabetically, act as substituents. -anoic replaces the -ane of the parent carbon chain. Adding -oic to the name of the parent chain follows the prefixes used for substituents. Carboxylic acids, on the other hand, get their names from the place where they’re isolated.

Question 2: Is ethanoic acid the same as vinegar?

Answer:

Ethanoic acid is referred to as “vinegar.” Acetic acid is another term for it. The common names of carboxylic acids come from the place where they were isolated. Vinegar is known as acetic acid because of its Latin name, acetum.

Question 3: Write the common name and IUPAC name of the following structures:

1. CH₃CH₂COOH
2. CH₃(CH₂)₄COOH
3. CH₃(CH₂)₅COOH

Answer:

• CH₃CH₂COOH

Common Name – Propionic acid

IUPAC Name – Propanoic acid

• CH₃(CH₂)₄COOH

Common Name – Caproic acid

IUPAC Name – Hexanoic acid

• CH₃(CH₂)₅COOH

Common Name – Enanthic acid

IUPAC Name – Heptanoic acid

Question 4: Explain the structure of Carboxylic acids in brief.

Answer:

A functional organic compound is a carboxyl group. A carbon atom is joined to an oxygen atom by a double bond in this carboxyl group structure. It also has a single hydroxyl group with which it is bonded. Carboxylic acids are carboxylated compounds. Many organic acids, such as acetic acid and amino acid, fall under this category.

On the sides of the molecules, the carboxyl group is usually present. The H atom contained in the hydroxyl group portion ionizes and is released as a free H+ ion or proton by the carboxyl group. The rest of the component, which is O, has a negative charge on it. The charge flows forward and backward in the space between the two oxygen molecules, keeping the ionization state stable.

Question 5: What are the components that make up the carboxyl group?

Answer:

The carboxyl group is made up of carbon atoms that have a hydrogen atom attached to them. Oxygen and the hydroxyl group are bonded together. Some more elements are linked to the Carboxyl group. Many qualities are provided by the compound that is created. Organic elements with carboxyl groups, such as carboxylic acids, are common. 

RCOOH is a symbol for the carboxyl group. R can represent any carbon-containing chemical or element. The carbon is connected to oxygen by a double bond and to the hydroxyl group, OH, by a single bond in this type of carboxylic group structure. Amino acids, fatty acids, keto acids, and other compounds are examples of carboxylic acids.

Question 6: Write the IUPAC name of the following compound –

Answer :

Heptane is the parent chain, which contains seven carbon atoms. So we’ve got heptanoic acid on our hands. On the priority list of functional groups, halogens and nitrile groups are at the bottom. As a result, they are treated as substitutes and are assigned a prefix. In alphabetical sequence, the prefix “fluoro” is applied to fluorine, whereas the prefix “cyano” is applied to nitrile.

Hence, IUPAC name of compound is,

3-cyano-6-fluoroheptanoic acid