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Carboxylic Acids

carboxylic acid, any class of organic compounds in which a carbon atom (C) is combined with an oxygen atom (O) in a double bond and a hydroxyl group (―OH) in a single bond. There is a fourth bond that binds a carbon atom to a hydrogen atom (H) or to another univalent combining group. The carboxyl group (COOH) is so named because of the carbonyl group (C = O) and the hydroxyl group.

A Carboxylic Acid is an organic compound that contain carboxyl functional group. They are present widely in nature and are also artificially manufactured by humans. Upon removing proton, carboxylic acids produce a carboxylate anion with the general formula R-COO–, which can form different types of useful salts such as soaps.

Carboxylic Acid Structure

The formula of a carboxylic acid is tha it is generally represented by the formula R-COOH, where COOH means to the carboxyl group, and R means to the remaining of the molecule to which this group is bonded to. In this carboxyl group, there is a C which shares a double bond with an O atom and a single bond with a -OH group.

A carboxylic acid generally has a formula of R-COOH, where COOH denotes the carboxyl group and R denotes the remainder of the molecule to which this group is linked. There is a carbon in this carboxyl group that has a double connection with an oxygen atom and a single bond with a hydroxyl group.

The first four carboxylic acids obtained from alkanes are methanoic acid (HCOOH), ethanoic acid (CH3COOH), propanoic acid (C2H5COOH) and butanoic acid (C3H7COOH).

It can be observed that a carboxylic acid contains a hydroxyl group attached to a carbonyl carbon. Due to the electronegativity of the O atom, this functional group can easily undergo ionization and release a proton.

The carboxylate ion, formed from the removal of a proton from the carboxyl group, is stabilized by the presence of two O atoms. Some examples of carboxylic acids are acetic acid  and Formic acid.

Nomenclature of Carboxylic Acids

Generally, these organic compounds are denoted by their trivial names, which contain the suffix “-ic acid”. An example of a trivial name which is for a carboxylic acid is acetic acid (CH3COOH).  According to IUPAC nomenclature of these compounds, the suffix “-oic acid” is assigned.

The guidelines that must be followed in the IUPAC nomenclature of carboxylic acids are listed below.

  • The suffix “e” in the name of the given alkane should be replaced with “oic acid”.

  • When the aliphatic chain has only one carboxyl group, the carboxylic carbon is always prioritised as one. For example, the compound CH3COOH is named as ethanoic acid.

  • When the aliphatic chain has more than one carboxyl group, the total number of C atoms is counted and the number of carboxyl groups is shown by Greek numeral prefixes such as “di-”, “tri-“, etc.

  •  Then this carboxylic acid is named by joining these prefixes and suffixes to the parent alkyl chain. Arabic numerals are used for indicating the positions of the carboxyl group.

  • The name “carboxylic acid” or “carboxy” can also be assigned for a carboxyl substituent on a carbon chain. An example of such nomenclature is the name 2-carboxyfuran for the compound 2-Furoic acid.

1. Physical Properties of Carboxylic Acids

  • Carboxylic acid molecules are polar because of the presence of two electronegative O atoms.

  • They also are responsible for hydrogen bonding due to the presence of the carbonyl group (C=O) and the -OH group.

  • When placed in nonpolar solvents, these compounds results in the formation of dimers via H bonding between the -OH group of one carboxylic acid and the carbonyl group of the other.

  • The solubility of compounds that are having the carboxyl functional group in water is dependent on the size of the compound. The smaller the compound (the smaller the R group), the higher will be the solubility.

  • The boiling point of a carboxylic acid is normally higher than that of water(100C).

  • These compounds have the ability to release protons and donate it and hence are therefore called Bronsted-Lowry acids.

  • They mainly have a strong sour smell. However, their esters have a very pleasant fragrance and are therefore used in perfumes manufacturing companies.

2. Chemical Properties of Carboxylic Acids

  • The α-Carbon present in a carboxylic acid can easily be halogenated via the Hell-Volhard-Zelinsky reaction.

  • Schmidt reactions can be used to transform these compounds into amines.

  • A carboxylic acid can be lessen to an alcohol by reacting it with H to cause a hydrogenation reaction.

  • In reaction with alcohols, these compounds produce esters.

Uses of Carboxylic Acids

  • Fatty acids that are important to human beings constitute carboxylic acids. Examples given omega-6 and omega-3 fatty acids.

  • In the manufacture of soaps, higher fatty acids are also used.

  • Many carboxylic acids are used in the production of soft drinks and many other food products.

  • The manufacture of rubber includes the use of acetic acid (coagulant).

  • In the manufacture of nylon-6,6 hexanedioic acid is used.

  • Carboxylic acids are very useful in the rubber, textile, and leather industries.

  • Ethylenediaminetetraacetic acid is a widely used chelating agent.

  • The manufacturing of many drugs involves the use of the said compounds. Therefore, carboxylic acids are very essential in pharmaceuticals.

  • The manufacturing of many polymers includes the use of compounds in which a carboxyl functional group is present.

Conclusion:-

The carboxylic acids are one of the most important functional group that present C=O. This type of organic compounds can be manufactured by different  methods, some carboxylic acids, such as lactic acid ,citric acid or fumaric acid are produced from by fermentation. Most of these types of carboxylic acids are used in the food industry.