Carboxyl Group | Definition , Structure & Examples

By | March 24, 2020

Carboxyl Group

Carboxyl Group Definition:

What is Carboxyl Group: A carboxyl group is a functional group that attaches to larger molecules and gives them specific properties. Carboxyl groups are present in many organic molecules called Carboxylic acids that have a variety of functions to perform. The carboxyl groups contain carbon bonded with both oxygen and hydroxyl groups. The hydroxyl groups are the bond of an oxygen molecule with a hydrogen molecule.
By this fact, carboxyl groups are polar and can participate in the bonding of hydrogen and a variety of reactions of other molecules. One important example of the carboxyl group is a synthesis of protein. Every amino acid contains both a carboxyl group and an amino group. The formed bond of these groups permits the amino acids to make chain together in a long sequence, called the Peptide bond. The carboxyl groups attached to a large variety of other molecules and perform a number of tasks in the biology field.

Carboxyl Functional Group

As we know the carboxyl group (COOH) is basically a functional group that consists of a one carbonyl group (C=O) combined with a hydroxyl group (O-H) which is attached to the same carbon atom. While carboxylic acids of acids and esters are called carboxylates.

Carboxyl Group

Carboxyl Group Structure

The structure of the carboxyl groups shows that double-bonded oxygen is electronegative and attracts hydrogen. The hydroxyl is the opposite of carboxyl and gives hydrogen in order to form another bond with the carbon.

Carboxyl Group

Carboxyl Group Properties

  1. They have an Electronegative oxygen atom which is double-bonded to a carbon atom.
  2. Within this, the carbon-oxygen bond is highly polar in nature. Due to the double bond polarity of the bond.
  3. As a result of the polarity, compounds containing carboxyl groups usually have higher melting points, boiling points and have hydrophilic centers.
  4. Moreover, the higher melting point and higher boiling point can be attributed to the fact that they can form hydrogen bonds both in the liquid and solid-state.
  5. Fatty acids are examples of compounds that have hydrophilic centers due to their carboxyl groups.
  6. Also, carboxyl groups, especially when present in molecules with a low molecular weight tend to be highly volatile and therefore tend to have strong odors.
  7. The pKa of carboxyl groups usually ranges from 4-5.

Carboxyl Group

Carboxyl Group Nomenclature

Common Names

The origination of the carboxyl group’s common name is from their Latin or Greek names. While carboxyl group common names end with the–ic acid suffix.

For example, the Formic acid structural formula is HCOOH. The origination of the name Formic Acid is from the “Formica” Latin word that means Ant. Formic acid is obtained from red Ants.

Vinegar is the natural source of Acetic acid. Its structural formula is (CH3COOH). In Latin for vinegar is “acetum” word is used.

Rotten butter is basically the source of Butyric acid that is known as Butyrum in Latin.

IUPAC Name

  1. The naming procedure of Aliphatic Carboxylic Acids is very easy. In the IUPAC system, “e” of the individual alkane is replaced with the word –oic acid.
  2. While the numbering of the carbon atom chain within a carboxylic acid starts from where the carboxylic carbon is present.
  3. It means that the carbon of the carboxyl group will always get the first number.
  4. According to the IUPAC system if more than one carboxyl group is present within a compound.
  5. You will use multiplicative prefix such as dicarboxylic acid, tricarboxylic acid, and so on.
  6. In short within the family of carboxylic acid members are named Methanoic acid, Ethanoic acid, Propanoic acid, Butanoic acid and so on based on the names of the Alkyl chain.
  7. While the IUPAC did not provide a standard form to name Aromatic carboxylic acids. They have IUPAC-approved specialized names such as benzoic acid.
  8. Within the IUPAC system carboxylic compounds named on the basis of the position of functional group and Alphabetical order.

carboxyl group

Carboxyl Group Bonding

Image result for carboxyl group bonding