ETHYL ALCOHOL: FORMULA, PROPERTIES, RISKS AND USES - CHEMISTRY - 2025

The ethyl alcohol, ethanol or alcohol, is an organic chemical compound class of the alcohols in the alcohol and is produced by yeast or by petrochemical processes. It is a colorless, flammable liquid and in addition to being a psychoactive substance, as a disinfectant and antiseptic, as a source of fuel for clean combustion, in the manufacturing industry or as a chemical solvent.

Ethyl alcohol's chemical formula is C ₂ H ₅ OH and its extended formula is CH ₃ CH ₂ OH. It is also written as EtOH and the IUPAC name is ethanol. Therefore, its chemical components are carbon, hydrogyne and oxygen. The molecule is made up of a two-carbon chain (ethane), in which one H has been replaced by a hydroxyl group (-OH). Its chemical structure is presented in Figure 1.

Figure 1: structure of ethanol

It is the second simplest alcohol. All carbon and oxygen atoms are sp3 allowing free rotation of the molecule boundaries. (Ethyl alcohol Formula, SF).

Ethanol can be found widely in nature because it is part of the metabolic process of yeast like Saccharomyces cerevisiae, it is also present in ripe fruit. It is also produced by some plants through anerobiosis. It has also been found in outer space.

Ethanol can be produced by yeast using fermentation of sugars found in grains such as corn, sorghum, and barley, as well as potato skins, rice, sugar cane, sugar beets, and yard trimmings; or by organic synthesis.

Organic synthesis is carried out through the hydration of ethylene obtained in the petrochemical industry and using sulfuric or phosphoric acid as a catalyst at 250-300 ºC:

CH ₂ = CH ₂ + H ₂ O → CH ₃ CH ₂ OH

Ethyl alcohol production

Ethanol from the fermentation of sugars is the main process for producing alcoholic beverages and biofuels. It is used mainly in countries such as Brazil, where yeast is used for the biosynthesis of ethanol from sugar cane.

Corn is the main ingredient for ethanol fuel in the United States. This is due to its abundance and low price. Sugarcane and beets are the most common ingredients used to make ethanol in other parts of the world.

Because alcohol is created through the fermentation of sugar, sugar crops are the easiest ingredients to convert to alcohol. Brazil, the world's second largest producer of fuel ethanol, produces most of its ethanol from sugar cane.

Most of the cars in Brazil are capable of running on pure ethanol or on a mixture of gasoline and ethanol.

Physical and chemical properties

Ethanol is a clear, colorless liquid with a characteristic odor and burning taste (Royal Society of Chemistry, 2015).

The molar mass of ethyl alcohol is 46.06 g / mol. Its melting point and boiling point are -114 ºC and 78 ºC, respectively. It is a volatile liquid and its density is 0.789 g / ml. Ethyl alcohol is also flammable and produces a smokeless blue flame.

It is miscible with water and most organic solvents such as acetic acid, acetone, benzene, carbon tetrachloride, chloroform and ether.

An interesting fact is that ethanol is also miscible in aliphatic solvents such as pentane and hexane, but its solubility depends on temperature (National Center for Biotechnology Information. PubChem Compound Database; CID = 702, 2017).

Ethanol is the best known representative of the alcohols. In this molecule, the hydroxyl group is on a terminal carbon, resulting in high polarization of the molecule.

Consequently, ethanol can form strong interactions, such as hydrogen bonding and dipole-dipole interaction. In water, ethanol is miscible and the interactions between the two liquids are so high that they give rise to a mixture known as azeotrope, with different characteristics to the two components.

Acetyl chloride and bromide react violently with ethanol or water. Mixtures of alcohols with concentrated sulfuric acid and strong hydrogen peroxide can cause explosions. Also mixtures of ethyl alcohol with concentrated hydrogen peroxide form powerful explosives.

Alkyl hypochlorites are violent explosives. They are easily obtained by reacting hypochlorous acid and alcohols in aqueous solution or mixed solutions of aqueous carbon tetrachloride.

Chlorine plus alcohols would also produce alkyl hypochlorites. They decompose in the cold and explode when exposed to sunlight or heat. Tertiary hypochlorites are less unstable than secondary or primary hypochlorites.

The reactions of isocyanates with base catalyzed alcohols must be carried out in inert solvents. Such reactions in the absence of solvents often occur with explosive violence (DENATURED ALCOHOL, 2016).

Reactivity and hazards

Ethyl alcohol is classified as a stable, volatile, and highly flammable compound. It will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. These can travel to the source of ignition and back off.

Most vapors are heavier than air. They will be spread along the ground and collected in low or confined areas (sewers, basements, tanks). There is a vapor explosion hazard indoors, outdoors, or in sewers. Containers may explode when heated.

Ethanol is toxic when ingested in large amounts or in large concentrations. It acts on the central nervous system as a depressive and diuretic. It is also irritating to the eyes and nose.

It is highly flammable and reacts violently with peroxides, acetyl chloride, and acetyl bromide. When in contact with some platinum catalysts it can ignite.

Symptoms in case of inhalation are cough, headache, fatigue, drowsiness. It can produce dry skin. If the substance comes into contact with the eyes it will cause redness, pain or a burning sensation. If ingested it produces a burning sensation, headache, confusion, dizziness and unconsciousness (IPCS, SF).

Eyes

If the compound comes into contact with the eyes, the contact lenses should be checked and removed. Eyes should be flushed immediately with plenty of water for at least 15 minutes with cold water.

Skin

In case of skin contact, the affected area should be rinsed immediately with plenty of water for at least 15 minutes while removing contaminated clothing and shoes.

Cover irritated skin with an emollient. Wash clothing and shoes before reuse. If the contact is severe, wash with a disinfectant soap and cover the contaminated skin with an antibacterial cream.

Inhalation

In case of inhalation, the victim should be moved to a cool place. If not breathing, artificial respiration is given. If breathing is difficult, give oxygen.

Ingestion

If the compound is ingested, vomiting should not be induced unless directed by medical personnel. Loosen tight clothing such as a shirt collar, belt, or tie.

In all cases, medical attention should be obtained immediately (Material Safety Data Sheet Ethyl alcohol 200 Proof, 2013).

Applications

Medicine

Ethanol is used in medicine as an antiseptic. Ethanol kills organisms by denaturing their proteins and dissolving their lipids and is effective against most bacteria, fungi, and many viruses. However, ethanol is ineffective against bacterial spores.

Ethanol can be administered as an antidote to methanol and ethylene glycol poisoning. This is due to the competitive inhibition of the enzyme that breaks them down called alcohol dehydrogenase.

Recreational

As a central nervous system depressant, ethanol is one of the most widely used psychoactive drugs.

The amount of ethanol in the body is typically quantified by the blood alcohol content, which is taken here as the weight of ethanol per unit volume of blood.

Small doses of ethanol generally produce euphoria and relaxation. People who experience these symptoms tend to be talkative and less inhibited, and may show poor judgment.

At higher doses, ethanol acts as a central nervous system depressant, producing progressively higher doses, impaired sensory and motor function, decreased cognition, stupefaction, unconsciousness, and possible death.

Ethanol is commonly used as a recreational drug, especially while socializing. You can also see what are the signs and symptoms of alcoholism?

Fuel

Ethanol's major use is as a motor fuel and fuel additive. Using ethanol can reduce dependence on oil and reduce greenhouse gas emissions (EGI).

The use of ethanol fuel in the United States has increased dramatically, from about 1.7 billion gallons in 2001 to about 13.9 billion in 2015 (US department of energy, SF).

E10 and E15 are ethanol and gasoline blends. The number after the "E" indicates the percentage of ethanol by volume.

Most of the gasoline sold in the United States contains up to 10% ethanol, the amount varies by area. All car manufacturers approve blends up to E10 in their gasoline cars.

In 1908, Henry Ford designed his Model T, a very old automobile, which ran on a mixture of gasoline and alcohol. Ford called this mixture the fuel of the future.

In 1919, ethanol was banned because it was considered an alcoholic beverage. It could only be sold when mixed with oil. Ethanol was used as fuel again after Prohibition ended in 1933 (US energy information administration, SF).

Other uses

Ethanol is an important industrial ingredient. It has wide use as a precursor to other organic compounds such as ethyl halides, ethyl esters, diethyl ether, acetic acid, and ethyl amines.

Ethanol is miscible with water and is a good general-purpose solvent. It is found in paints, stains, markers, and personal care products such as mouthwashes, perfumes, and deodorants.

However, polysaccharides precipitate from aqueous solution in the presence of alcohol, and ethanol precipitation is used for this reason in the purification of DNA and RNA.

Due to its low melting point (-114.14 ° C) and low toxicity, ethanol is sometimes used in laboratories (with dry ice or other refrigerants) as a cooling bath to keep containers at temperatures below the point of water freezing. For the same reason, it is also used as an active fluid in alcohol thermometers.

Biochemistry

The oxidation of ethanol in the body produces an amount of energy of 7 kcal / mol, intermediate between carbohydrates and fatty acids. Ethanol produces empty calories, which means that it does not provide any type of nutrient.

After oral administration, ethanol is rapidly absorbed into the bloodstream from the stomach and small intestine and distributed in total body water.

Because absorption occurs more rapidly from the small intestine than from the stomach, delays in gastric emptying delay the absorption of ethanol. Hence the concept of not drinking on an empty stomach.

More than 90% of the ethanol that enters the body is completely oxidized to acetaldehyde. The rest of the ethanol is excreted through sweat, urine, and through respiration (breath).

There are three ways in which the body metabolizes alcohol. The main pathway is through the enzyme alcohol dehydrogenase (ADH). ADH is located in the cytoplasm of cells. It is found primarily in the liver, although it is also found in the gastrointestinal tract, kidneys, nasal mucosa, testes, and uterus.

This enzyme is dependent on the oxidized coenzyme NAD. It is the most important in the oxidation of ethanol, since it metabolizes between 80 and 100% of ingested ethanol in the liver. Its function is to oxidize alcohol to acetaldehyde according to the reaction:

CH ₃ CH ₂ OH + NAD ⁺ → CH ₃ CHO + NADH + H ⁺

Another way to metabolize alcohol is through the enzyme catalase, which uses hydrogen peroxide to oxidize alcohol to acetaldehyde in the way:

CH ₃ CH ₂ OH + H ₂ O ₂ → CH ₃ CHO + 2H ₂ O

This pathway is limited by the low rates of H ₂ O ₂ generation that are produced under cellular conditions by the enzymes xanthine oxidase or NADPH-oxidase.

The third way of metabolizing alcohol is through the microsomal ethanol oxidation system (SMOE). It is a system for the elimination of toxic substances from the organism located in the liver, consisting of oxidase enzymes of mixed function of cytochrome P450.

Oxidations modify drugs and foreign compounds (xenobiotics) by hydroxylation, making them non-toxic. In the specific case of ethanol the reaction is:

CH ₃ CH ₂ OH + NADPH + H ⁺ + O ₂ → CH ₃ CHO + NADP ⁺ + 2H ₂ O

When ethanol is converted to acetaldehyde by these three enzymes, it is oxidized to acetate by the action of the enzyme aldehyde dehydrogenase (ALDH). This enzyme is dependent on the oxidized coenzyme NAD and the reaction is:

CH ₃ CHO + NAD + + H ₂ O → CH ₃ COOH + NADH + H ⁺

Acetate is activated with coenzyme A to produce acetyl CoA. This enters the Krebs cycle for energy production (US National Library of Medicine, 2012).

The importance of the hydroxyl group in alcohols

The hydroxyl group is a molecule made up of an oxygen atom and a hydrogen atom.

This results in a water-like molecule with a net negative charge that binds to the carbon chain.

This molecule makes the carbon chain an alcohol. Furthermore, it provides certain general characteristics to the resulting molecule.

Contrary to alkanes, which are nonpolar molecules due to their carbon and hydrogen chains, when a hydroxyl group adheres to the chain, it acquires the ability to be soluble in water, due to the resemblance of the OH molecule to water.

However, this property varies depending on the size of the molecule and the position of the hydroxyl group on the carbon chain.

The physicochemical properties change depending on the size of the molecule and the distribution of the hydroxyl group, but in general alcohols are usually liquid with a characteristic odor.

References

1. DENATURED ALCOHOL. (2016). Recovered from cameochemicals.noaa.gov.
2. Ethyl alcohol Formula. (SF). Recovered from softschools.com.
3. (SF). ETHANOL (ANHYDROUS). Recovered from inchem.org.
4. Material Safety Data Sheet Ethyl alcohol 200 Proof. (2013, May 21). Recovered from sciencelab.com.
5. National Center for Biotechnology Information. PubChem Compound Database; CID = 702. (2017, March 18). PubChem Compound Database; CID = 702. Recovered from pubchem.ncbi.nlm.nih.gov.
6. Royal Society of Chemistry. (2015). Ethanol. Recovered from chemspider.com
7. S. department of energy. (SF). Ethanol. Recovered from fueleconomy.gov.
8. S. energy information administration. (SF). Ethanol. Recovered from eia.gov.
9. S. National Library of Medicine. (2012, December 20). HSDB: ETHANOL. Recovered from toxnet.nlm.nih.gov.