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Butanoic Acid – Structure, Properties, Uses

Apr 24, 2023

Butanoic Acid

The carboxylic acid, butanoic acid, has the structural formula CH3CH2CH2-COOH. Salts and esters of butanoic acid are known as butyrates. It has a foul odour, a bitter flavour, and a sweet aftertaste reminiscent of ether. The acid is a clear, oily solvent that may be distinguished from an aqueous medium by being saturated with salts like calcium chloride. It dissolves easily in ethanol, ether, and water solutions.

Butanoic acid, together with acetic acid and propionic acid, is one of the three most prevalent short-chain fatty acids (SCFAs) in the stomach. Other names for it are butyric acid and ethyl acetic acid.


This article will discuss what butanoic acid is, its properties, production, and uses.

What is Butanoic Acid?

The structure includes a saturated short-chain fatty acid with 4-carbon molecules. Butanoic acid in its esterified form is generally present in plant and vegetable fats. The formula is C4H8O2. In 1818, the French scientist Michel Eugène Chevreul made this acid known to science. Because it was first discovered in stale butter, it is often referred to as butyric acid, a direct translation of the phrase “butter acid.” Fermenting starches and oxidizing n-butyl alcohol create it.


Butanoic Acid Structure

Let us now look at the butanoic acid structure. Butanoic acid, also known as butyric acid has the formula C4H8O2; where the functional group attached is -COOH.

Butanoic acid is produced by butter in amounts between 3 and 4 per cent. Glycerol hydrolysis releases the rancidity from butter. Butanoic acid, a common carboxylic acid, frequently reacts with bases and is a target for many metals.


The buttery flavour and foul odour characterize butanoic acid. Mammals, such as canines can detect this at 10 ppb. Contrarily, this acid is only detectable by humans at levels greater than 10 ppm.

The -COOH functional group has an sp2 hybridized carbon with close to 120 degrees bond angles.


Physical Properties of Butanoic Acid

The following are some of the butanoic acid’s crucial physicochemical characteristics:

  • Butanoic acid, sometimes referred to as butyric acid, is a foul-smelling liquid that is greasy and colourless.
  • The formula for butanoic acid is C4H8O2.
  • This acid may be dissolved in alcohol, ether, and water.
  • At 437 K, it reaches its melting point.
  • Butanoic acid has a boiling point of 268 Kelvin.
  • Its density as the liquid is 1.135 g/cm3.
  • The pKa of butanoic acid is 4.82, which implies that it is a weak acid.

Chemical Properties of Butyric Acid

The sodium salt of butanoic acid, which is likewise composed of water and carbon dioxide, is produced when butanoic acid reacts with sodium hydroxide (NaOH).


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

Ether and acetic acid are created once the acid is handled with water. The chemical formula for this is as follows.


H2O + C4H8O2 → CH3COOH + C2H6O

Production of Butyric Acid

Although the esters of the acid are widely dispersed in nature, the acid itself is not. It is a common industrial chemical and an essential component of the digestive tract in mammals. It may be found in cow milk, human milk, dairy goods including milk and cheese, body odour, plant and animal lipids, and as a result of anaerobic fermentation. The colon also contains it.


Production in Industry

Propene and syngas undergo hydroformylation to produce butyraldehyde, which is oxidized to produce butanoic acid in an industrial environment.

H2 + CO + CH3CH=CH2 → CH3CH2CH2CHO → butanoic acid

It may be eliminated from aqueous solutions by diluting it with acids like calcium chloride. The calcium salt, Ca(C4H7O2)2H2O, is more difficult to dissolve in hot water than in cold water.

Synthesis by Microbes

Butyrate is produced by various fermentation reactions carried out by essential anaerobic bacteria. In 1861, Louis Pasteur made this fermentation process well-known. Bacteria that generate butyrate include, for example:

  • Clostridium butyricum
  • Eubacterium limosum
  • Clostridium kluyveri
  • Clostridium pasteurianum
  • Fusobacterium nucleatum

As in many species, the pathway is started by the digestion of glucose into two atoms of pyruvate. Pyruvate is oxidized to create acetyl coenzyme A. As a result, two molecules of carbon dioxide (CO2) and hydrogen (H2) are created. ATP is then produced during the fermentation’s final phase. Three molecules of ATP are produced for each molecule of glucose, which is a relatively high yield. The modified chemical equation for fermentation is:

C6H12O6 → C4H8O2 + 2 CO2 + 2 H2

Uses of Butanoic Acid

  • Butanoic acid has many important applications in the chemical, culinary, and pharmaceutical industries.
  • Butanoic acid is widely used in the chemical industry to produce thermoplastics such as cellulose acetate butyrate.
  • The production of plastics requires the use of additional esters, such as glycerol tributyrate.
  • Butanoic acid is commonly used as a food preservative to enhance fruit scent and to give food tastes buttery undertones.
  • The principal energy source for the human body is butanoic acid, a form of short-chain fatty acid created by microbial digestion of dietary fibres in the colon. Butanoic acid is also a recognized colorectal cancer inhibitor.
  • Its biological characteristics, which include therapeutic advantages for cancer and gastrointestinal conditions, have been well studied.

How is Butanoic Acid Used in Different Industries?

Industrial Chemistry

  • Butyric acid has the chemical formula C4H8O2.
  • It is primarily used as a substrate to manufacture the copolymer cellulose acetate butyrate (CAB). It has better flexibility and resistance to heat and cold and performs well in organic solvent breakdown.
  • Butanoic acid may also be directly incorporated into plastic goods and textiles for increased resistance to heat and light.
  • Butanoic acid can also be used to enhance butanol production as a fuel.

Veterinary Industry

  • It acts as an agent in the field of animal feed, supplying energy and encouraging salt and water absorption.
  • It keeps the animal’s digestive system healthy and guards against illnesses.
  • The epithelium is encouraged to increase by butanoic acid.

Fragrance Industry

  • Esters of butanoic acids, such as methyl, ethyl, and amyl butyrate, are used as aromatic ingredients in perfume production and to enhance fruit fragrance.
  • It serves as a bactericide and aids in maintaining the electrolyte balance in perfumes.

Medicinal Industry

  • To keep the cells safe from dangerous compounds and the stomach healthy and disease-free, butyrate is used. Waste is stored in the colon for later disposal. It has been discovered that butyrate increases antioxidant levels, lowering the risk of developing inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS).
  • Butanoic acid has been found to both prevent and treat colon cancer because it prevents the growth of colorectal tumour cells.
  • Additionally, it can be found in anti-anxiety medications.

Butanoic Acid Hazard and First Aid

Human skin, breath, saliva, and excreta contain butanoic acid, a vital component of a healthy metabolism. It is typical in all dairy products, including butter. Butanoic acid in liquid form can cause corrosion if it touches the skin or eyes. It is a flammable substance that might cause severe skin burns and eye damage. Aquatic life is also negatively impacted for a long time.

Please ensure that the Following Precautions are taken:

  • To avoid problems, take precautions by carefully reading the label before usage.
  • Avoid breathing in the gas’s vapours, mists, or particles.
  • Wash your skin well after handling.
  • Put on the proper gloves, clothing, and eye and face masks.
  • Maintain butanoic acid away from flames and heat sources due to its great flammability.
  • Stay away from spraying acid into the air.

In the Event of Unintentional Contact

  • Eye contact: If you unintentionally get acid in your eyes, rinse them thoroughly with water for at least 30 minutes while lifting your upper and lower eyelids. Remove any contacts you may be wearing. Make a doctor’s appointment right away.
  • After skin contact, immediately remove any contaminated clothing. Immediately wash the skin with plenty of water.
  • Inhalation: If someone inhales, remove them from the exposure. If the heart has stopped beating, do CPR; if the respiration has stopped, start rescue breathing.

Does Butyric Acid have any Side Effects? 

Butyric acid’s safety is currently unknown due to a lack of clinical evidence. The researchers reported no side effects at a dose of 300 mg per day in the previously mentioned study Trusted Source which found that butyric acid supplementation may improve IBS symptoms. However, if pregnant or breastfeeding, you should avoid taking butyric acid supplements.

According to one animal study, giving pregnant and breastfeeding rats sodium butyrate resulted in insulin resistance and increased fat storage in their offspring.


Butanoic acid, one of the healthiest short-chain fatty acids, is crucial for enhancing digestive wellness, lowering inflammation, safeguarding the brain, managing weight, and avoiding cancer. Meals you can’t absorb are turned into butyrate by intestinal bacteria, which has several advantageous health consequences. Your gut flora may create more butanoic acid if you include more fibre in your diet.

Butanoic acid and related derivatives are widely used in the chemical, agricultural, medicinal, perfume, and animal feed industries. Butanoic acid is widely used as a pure acid to intensify odours that mimic butter in taste, even though it has a foul smell on its own.

Frequently Asked Questions

1. What is butyric acid’s formula?

The structural formula for butyric acid, also known as butanoic acid, is CH3CH2CH2COOH., where the functional group connected is -COOH. It contains 4 carbon atoms and is sp2 hybridized.

2. What is the process for making butanoic acid?

Butyraldehyde oxidation can be used to make butyric acid in industrial settings. It can be separated from aqueous solutions by saturating it with minerals like calcium chloride. When incorporated in hot water, the calcium salt, Ca(C4H7O2)2H2O, is considerably less soluble.

3. What advantages does butanoic acid offer?

The advantages of butyrate include the following:

  • Loss of weight
  • Stimulates and defends the immune system
  • Boost digestion
  • Reduces the risk of cancer
Butanoic Acid


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