Is ethanol biodegradable? (5 chemical reactions of ethanol)

This blog article shall answer the question, “is ethanol biodegradable?.

It shall also cover other areas such as:

  • Properties of ethanol.
  • Uses of ethanol.
  • Eco-friendliness of ethanol.
  • Ethanol and health.

Is ethanol biodegradable?

Yes, ethanol is biodegradable because it is a natural organic compound derived mostly from fermentation or by hydration of ethene gas.

Ethanol is one of the most produced organic compounds and has one of the most consumption rates.

Ethanol is readily broken down by bacterial, fungal, or body enzymes to produce water and carbon dioxide.

Ethanol is categorized as a food-grade beverage and therefore is safe to consume.

But how is ethanol produced? Let’s dive into this question.

How is alcohol synthesized?

Alcohol is an organic compound with the formula C2H5OH.

It has several names like ethyl-alcohol, drinking alcohol, or grain alcohol.

Alcohol can be naturally produced by microorganisms such as yeasts through fermentation or by industrial hydration of ethylene gas.

Natural synthesis.

Alcohol is a natural product of yeast metabolism. It is commonly found in yeast inhabited areas such as overripe fruits or during germination of some species of plants.

The most popular yeast species used is Saccharomyces cerevisiae. The yeast breaks down sugars such as starch or cellulose to produce ethanol and carbon dioxide using amylase enzymes.

In yeast fermentation to produce ethanol, three types of substrates can be used.

  • Starch-containing substrate.
  • Sugar beet, Molasses, or sugar cane juice.
  • Cellulose from wood/processed wood waste products.

When starch and yeast strains are used, the starch has to be converted to simple sugars which can be acted upon by yeast.

It is converted by two methods which include hydrolysis and germination.

In hydrolysis, the objective is to convert starch into amylose. The product is then supplemented with cellulase enzymes from Microbial organisms which convert starch into reducing sugars.

In the germination process, the target is to convert starch into amylose because yeast doesn’t have amylase enzymes.

Starch is germinated into malt, a process called malting, this process activates amylase enzymes.

The amylase enzymes convert starch into simple sugars.

After the starch has been converted into simple sugars, the Yeast enzymes break down the sugars into ethanol and carbon dioxide.

For commercial, large-scale production of alcohol, fermentation is carried out under the conditions of pH 5 and a temperature of 35⁰ Celsius.

After the fermentation process is over, ethanol is harvested and the biomass of yeast is used as single-cell protein for animal feeds.

When cellulose as a substrate is used, the source of cellulose includes wood, corncobs, straw, and sawdust.

Industrial synthesis.

Ethanol is produced in industries by hydration of ethylene gas.

Ethene gas is reacted with water in the presence of catalysts such as phosphoric acid to form ethanol.

This process is employed in the large-scale production of ethanol for commercial purposes.

Ethanol is purified through distillation. Distillation increases the concentration of ethanol to the required levels.

Grades of ethanol.

Alcohol can be categorized in different grades depending on the concentration, quality or additives added.

The different grades include:

Denatured alcohol.

Alcohol is usually treated as a beverage or drug. As a result, it tends to be highly taxed by authorities. 

To avoid over-taxation, industries add additives to make ethanol not suitable for consumption. Such additives include:

  • Denatonium benzoate.
  • Methanol.
  • Naphtha.
  • Pyridine.

Absolute alcohol.

This is a category of alcohol with very low water content.

Water removal is done through azeotropic distillation whereby a mixture of two compounds with the same boiling point is used, the most popular azeotropic mixture used is benzene-water and alcohol.

Due to its high concentration, absolute alcohol is good for consumption. Its main purpose is:

  • Solvent for laboratory tests.
  • As a fuel.
  • The solvent in ultraviolet-visible spectroscopy.

Rectified spirits.

This is an azeotropic mixture of 96% alcohol and 4% water.

Properties of ethanol.

The following are the properties of ethanol.

  • It is a liquid.
  • It has a boiling point of 78⁰ Celsius.
  • It is soluble in water.
  • It can react with many chemical compounds.
  • It is highly flammable.
  • It is volatile.
  • It is soluble in organic solvents.

Uses of ethanol.

Ethanol has a wide range of uses which include the following:

  • Ethanol is used as an alcoholic beverage.
  • It is used as an industrial solvent.
  • It is used as a food preservative.
  • It is used as a surgical spirit in hospitals.
  • It is used in the making of cosmetics and perfumes.
  • It is used as hand sanitizer.
  • Used in making deodorants.
  • Used in making of paints, and inks.
  • It is used in pharmaceutical in making drugs.
  • It is used in motors and aircraft as a gasoline mixture.
  • It is used as a resin solvent.
  • Ethanol is used as a biofuel.
  • Used in the medical field as an antiseptic.
  • Used in sterilization of laboratory equipment.

What are the chemical reactions of ethanol?

Ethanol can be used in a lot of reactions to form different compounds meant for various purposes.

Ester formation.

Ethanol reacts with carboxylic (organic) acids in the presence of sulfuric or phosphoric acid to form esters; this reaction is called esterification.

The esters can react with acids or bases to form soaps, a process called saponification.


Ethanol can be converted into ethene gas in the presence of inorganic acid such as sulfuric acid. This process removes water molecules from ethanol.

The process also requires a very high temperature.


Combustion is the breakdown of a compound using a flame or fire.

Complete combustion of ethanol produces carbon dioxide and water while incomplete combustion will produce ethene gas.

Acid-base conversion.

Ethanol is a neutral molecule with a pH of almost the same as water.

Ethanol can be converted into its conjugate base (the ethoxide) ion by a reaction with an alkali metal like sodium or a strong base such as sodium hydroxide.


Ethanol can be reacted with hydrogen halides to produce ethyl halide molecules.

This reaction requires a catalyst such as zinc chloride or an acid such as sulfuric acid.


Ethanol can be converted into acetaldehyde and further oxidized to acetic acid depending on the reagents used and the conditions of the reactions.

The reactions occur mostly in the human body and are carried out by alcohol dehydrogenase enzymes.

The acetic formed in the body is a precursor for energy, and so ethanol is used as a nutrient in the body.


Ethanol is treated as food, same as fats, proteins, and carbohydrates in the body.

It is broken down by alcohol dehydrogenase enzymes into acetaldehyde which is then converted to acetic acid, a source of energy for the body.

Is ethanol toxic?

Yes, alcohol can be toxic to the body when not used in the right way.

As mentioned earlier, ethanol occurs in different forms. Some forms are brought about to prevent the consumption of alcohol.

Ethanol in the form of surgical spirit and absolute alcohol is not safe for ingestion.

Absolute ethanol has a very high concentration which can cause nervous system breakdown resulting in poor judgment, alterations of moods, consciousness, cognition, and behavior.

Absolute ethanol also irritates the skin and eyes, causes nausea and vomiting, and also causes intoxication.

Surgical spirits contain methanol which is not safe for consumption and can lead to poisoning.

Overconsumption of alcohol or long-time use can cause liver cirrhosis, liver cancer, and methanol poisoning.

Is Ethanol eco-friendly?

Yes, ethanol is eco-friendly. This is according to a report. It is broken down by bacteria into water and carbon dioxide which are non-toxic to the environment.


This blog has answered the question of the biodegradability of ethanol.

It has also covered other areas such as:

  • Properties and uses of ethanol
  • Processing and synthesis of ethanol.
  • Chemical reactions of ethanol.
  • Eco-friendliness of ethanol.
  • Toxicity of ethanol.

For any questions or comments please use the comment section below.

Frequently Asked Questions (FAQs): is ethanol biodegradable?

What are the disadvantages of ethanol?

Ethanol is very volatile and flammable and can easily ignite a fire.

Overconsumption of ethanol can cause intoxication and liver damage.

Some forms of ethanol such as absolute ethanol are poisonous to the body.

Is ethanol toxic?

Yes, ethanol is toxic to the human body. Ethanol should be consumed responsibly because it can cause intoxication and interfere with one’s judgment.

Can I drink ethanol?

Yes, one can drink ethanol, albeit with age qualification as stipulated in a country’s laws.

However, Ethanol should be taken responsibly to avoid intoxication.


Pohorecky, Larissa A.; Brick, John (January 1988). “Pharmacology of ethanol”. Pharmacology & Therapeutics. 36 (2–3): 335–427. doi:10.1016/0163-7258(88)90109-X

Ballinger P, Long FA (1960). “Acid Ionization Constants of Alcohols. II. Acidities of Some Substituted Methanol and Related Compounds 1,2”. Journal of the American Chemical Society. 82 (4): 795–798. doi:10.1021/ja01489a008.

Martini, A. (1992). “Biodiversity and conservation of yeasts”. Biodiversity and Conservation. 1 (4): 324–333. doi:10.1007/BF00693768. 

Seager, Spencer L.; Slabaugh, Michael R. (2004). Chemistry for Today: General, Organic, and Biochemistry. Thomson Brooks/Cole. p. 342. ISBN 9780534399696. OCLC 155910842