Butanoic Acid - C₄H₈O₂

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What is Butanoic Acid?

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Butanoic acid is an oily and colourless liquid having the chemical formula CH3CH2CH2-COOH. It is a type of short-chain saturated fatty acid, which is found in the form of esters in plant oils and animal fats. In 186, Lieben and Rossi discovered the Butanoic acid. It is also known as butyric acid, which is meant by the butter acid because it was first discovered in rancid butter. And it was prepared by the fermentation of the butyric carbohydrates and also by the oxidation of n-butyl alcohol.

The other names of this acid are given as n-Butyric acid, butyric acid, and n-Butanoic acid.

Butanoic Acid Structure

Let us look at the butanoic acid structure given below:

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Properties of Butanoic acid

Let us discuss a few properties of Butanoic acid as tabulated below.


Butanoic acid

Butanoic acid formula or butyric acid formula or structural formula of butanoic acid


Molecular Weight or Molar Mass

88.11 g/mol


960 kg/m³

Boiling Point

163.5 °C

Melting Point

-7.9 °C

Chemical Formula


Physical Properties of Butanoic acid - C4H8O2

A few of the physical properties of Butanoic acid are listed as follows.

  • Butanoic acid has an odor as Unpleasant odor,

  • Its appearance is Colourless clear liquid,

  • It has the covalently bonded unit as 1,

  • The heat capacity of the butanoic acid can be given as 298.15 K, 1 atm,

  • Its complexity is 49.5,

  • The solubility of the butanoic acid is Miscible in water and ethanol.

Chemical Properties of the Butanoic acid - C4H8O2

  • Butanoic acid reacts with the sodium hydroxide and forms carbon dioxide, the sodium salt of butanoic acid, and water. The chemical equation can be given as follows.

21C₄H₈O₂ + 20NaOH   →  20NaC₄H₆O + 4CO₂ + 34H₂O

  • Butanoic acid, on treatment with the water, produces ether and acetic acid. The chemical equation can be given as follows.

C₄H₈O₂ + H₂O  →  CH₃COOH + C₂H₆O

Occurrence of Butanoic Acid

The triglycerides of butyric acid compose 3 to 4 percent of butter. When the butter goes rancid, the butyric acid liberates from glyceride using the hydrolysis process. It is one of the fatty acid subgroups, which is known as short-chain fatty acids. Butyric acid is also a typical carboxylic acid, reacts with bases, and affects various metals. It is found in plant oils, animal fat, breast milk, bovine milk, butter, body odor, parmesan cheese, vomit, and also as an anaerobic fermentation product (including in the colon).

It has a kind of taste like butter and gives an unpleasant odor. Mammals having good scent detection abilities, like dogs, can detect this at 10 parts per billion. At the same time, humans can detect this acid only in concentrations above 10 parts per million. In the manufacturing of food, it can be used as a flavoring agent.

In humans, this acid is one of two primary endogenous agonists of the human hydroxycarboxylic acid receptor 2 (HCA2), which is a receptor of Gi/o-coupled G protein-coupled.

Butyric acid is available as its octyl ester in the seed of the ginkgo tree and in parsnip (Pastinaca sativa).

Production of Butyric Acid

Fermentable Fiber Sources

Highly-fermentable fiber residues, like those from oat bran, resistant starch, pectin, and guar, are transformed by the colonic bacteria into short-chain fatty acids (SCFA) like butyrate, producing more SCFA to that of less fermentable fibers, including celluloses. A study found that resistant starch produces consistently more butyrate compared to the other dietary fiber types. Production of SCFA from fibers in ruminant animals like cattle is responsible for the butyrate content of butter and milk.

Uses of Butyric acid

Butyric acid can be used in various butyrate ester preparation. It can also be used to produce cellulose acetate butyrate (CAB), which is helpful to use in a wide range of paints, tools, and coatings, and it is also more resistant to degradation compared to cellulose acetate. However, CAB can be degraded with exposure to moisture and heat, releasing butyric acid.

The butyric acid esters of low-molecular-weight, such as methyl butyrate, have mostly pleasant tastes or aromas. As a consequence, these can be used as perfume and food additives. It is also considered as an approved food flavoring in the EU FLAVIS database (08.005).

Because of its powerful odor, it can also be used as a fishing bait additive. Many commercially available flavors used in carp (Cyprinus carpio) baits will use butyric acid as their ester base. But, it is unclear whether fish are self attracted by the butyric acid or by the substances added to it. However, Butyric acid was one of the few organic acids shown to be palatable for both bitterling and tench. This substance has also been used as a stink bomb by SSCS (Sea Shepherd Conservation Society) in disrupting the Japanese whaling crews.

FAQ (Frequently Asked Questions)

1. Explain the Preparation of Butanoic Acid?

Ans: Industrially, butyric acid can be prepared using Butyraldehyde oxidation. Saturation with the salts like calcium chloride can isolate it from the aqueous solutions. Calcium salt, Ca(C4H7O2)2·H2O, is relatively less soluble when dissolved in hot water.

2. Explain what Fructans is.

Ans: Fructans are the other prebiotic soluble dietary fiber source that is digested to form butyrate. These are often found in the food soluble fibers, which are high in sulfur, like cruciferous vegetables and allium. The fructans sources include wheat (although a few wheat strains like spelt with lower amounts), barley, rye, onion, garlic, and many more.

3. Give some information on Microbial Biosynthesis of Butanoic Acid?

Ans: Butyrate can be generated using multiple fermentation processes that are performed by the obligatory anaerobic bacteria. This fermentation pathway was discovered by Louis Pasteur in 1861. Some examples of bacteria that produce butyrate are Clostridium kluyveri, Clostridium butyricum, and Clostridium pasteurianum.

4. Explain the reactions of Butanoic Acid?

Ans: Butyric acid reacts as a carboxylic acid, typically, and it can form ester, amide, chloride, and anhydride derivatives. Commonly, the latter, butyryl chloride, can be used as an intermediate to obtain the others.