Carboxylic Acids, Introduction, Structure, Classification And Nomenclature
Shrivastav 26 Jun, 2024
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Introduction Of Carboxylic Acids : Organic substances that have carboxyl (—COOH) groups are known as carboxylic acids. Because it is composed of both hydroxyl (—OH) and carbonyl (C = O) groups, the carboxyl group gets its name. The primary functional group of carboxylic acid is carbonyl (C = O) group. These organic compounds can be obtained through various methods. Fermentation is one way to produce some carboxylic acids, like fumaric acid, lactic acid, and citric acid, which are mostly used in the food industry.
They are widely found in nature and are also created artificially by people. Deprotonation of carboxylic acids results in the formation of a carboxylate anion, which has the general formula R — COO – and can form a range of practical salts, including soaps.
Carboxylic Acid Structure
A carboxylic acid’s general formula is 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.
Carbon and oxygen in the carbonyl are both sp 2 hybridized, resulting in a basic trigonal shape. The hydroxyl oxygen has also undergone sp 2 hybridization, allowing one of its lone pair electrons to conjugate with the carbonyl group's pi system. This makes the carboxyl group planar, which can be represented by the resonance structure shown below.
Reason carboxylic acids get their name is because they can give up a hydrogen atom to create a carboxylate ion. We will talk about the factors later on that influence how acidic carboxylic acids are.
Classification Of Carboxylic Acid
C arboxyl group is typically denoted as —COOH. The carboxylic acid can be aliphatic (R—COOH) or aromatic (Ar—COOH), depending on whether —COOH is attached to an alkyl (or hydrogen) or aryl group. Carboxylic acid is acidic because it contains replaceable hydrogen atoms in the carboxyl group. Because each carboxyl acid contains one replaceable hydrogen, an acid with one carboxyl group is monobasic and referred to as monocarboxylic acid. Similarly, acids with two or three carboxyl groups are known as dicarboxylic (dibasic) and tricarboxylic (tribasic) acids, respectively.
Monocarboxylic Acids: Monocarboxylic acids are organic acids that contain a single carboxyl group. Aliphatic monocarboxylic acids are known as fatty acids because some of their higher members, such as palmitic acid (C 15 H 31 COOH) and stearic acid (C 17 H 35 COOH), were first obtained through fat hydrolysis.
They have C n H 2n O 2 or C n H 2n–1 COOH as their general formula. Their nature is monobasic. Examples include acetic acid (CH 3 COOH), formic acid (HCOOH), etc.
Dicarboxylic Acids: Dicarboxylic acids are organic acids that contain two carboxyl groups.
Tricarboxylic Acids: Tricarboxylic acids are organic acids defined as having three carboxyl groups.
Aromatic acids: Compounds with a COOH group bound to an aromatic ring are classified as aromatic acids. Benzoic acid is the most basic aromatic acid.
Nomenclature of Carboxylic Acids: These organic compounds are commonly known by their trivial names, which end in "-ic acid." Acetic acid (CH 3 COOH) is an example of a trivial name for a carboxylic acid. The suffix "-oic acid" is applied to these compounds in the IUPAC nomenclature.
Rules For Iupac Nomenclature Of Carboxylic Acids
- In the name of the corresponding alkane, "oic acid" is used instead of the suffix "e".
- Carboxylic carbon is always numbered one when the aliphatic chain only has one carboxyl group. As an illustration, CH 3 COOH is known as ethanoic acid.
- The total number of carbon atoms is counted when an aliphatic chain has multiple carboxyl groups, and the number of carboxyl groups is represented by Greek numeral prefixes like "di-," "tri-," etc.
- Prefixes and suffixes are added to the parent alkyl chain to give a carboxylic acid its name. The locations of the carboxyl groups are denoted by Arabic numerals.
- A carboxyl substituent on a carbon chain may also be referred to as "carboxylic acid" or "carboxy". The compound 2-Furoic acid is known as 2-carboxyfuran, which is one example of such nomenclature.
Common And Iupac Names Of Carboxylic Acids
|
Formula |
Common Name |
IUPAC Name |
|
HCOOH |
Formic acid |
Methanoic acid |
|
CH 3 COOH |
Acetic acid |
Ethanoic acid |
|
CH 3 CH 2 COOH |
Propionic acid |
Propanoic acid |
|
CH 3 (CH 2 ) 2 COOH |
Butyric acid |
Butanoic acid |
|
CH 3 (CH 2 ) 3 COOH |
Valeric acid |
Pentanoic acid |
|
CH 3 (CH 2 ) 4 COOH |
Caproic acid |
Hexanoic acid |
|
C 4 H 8 O 2 |
Isobutyric acid |
2-methylpropanoic acid |
|
C 4 H 7 BrO 2 |
|
2-bromobutanoic acid |
|
CH 3 (CH 2 ) 8 COOH |
Capric acid |
Decanoic acid |
|
CH 3 (CH 2 ) 10 COOH |
Lauric acid |
Dedocanoic acid |
|
CH 3 (CH 2 ) 12 COOH |
Myristic acid |
Tetradecanoic acid |
|
CH 3 (CH 2 ) 14 COOH |
Palmitic acid |
Hexadecenoic acid |
|
CH 3 (CH 2 ) 16 COOH |
Stearic acid |
Octadecanoic acid |
Examples Of Carboxylic Acids
Naming Salts of Carboxylic Acids:
Carboxylic Acids FAQs
Q.1 : Why is acidity found in carboxylic acids?
Q.2 : Which Carboxylic Acid is present in human blood?
Q.3 : What foods contain carboxylic acids?
Q.4 : What is a carboxylic acid used for?
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