Difference Between Isopropyl and Ethyl Alcohol

Difference – Isopropyl vs Ethyl Alcohol

Isopropyl and Ethyl Alcohol are two organic compounds. The primary functional group of alcohols is –OH group. They are named according to the number of carbon atoms they have. Ethyl alcohol has got two carbon atoms whereas isopropyl alcohol has got three carbon atoms. The difference in their chain length is the main difference between Isopropyl and Ethyl Alcohol.

This article explains,
1. What is Ethyl Alcohol
     – Structure, Molecular Formula, Properties, Uses
2. What is Isopropyl
     – Structure, Molecular Formula, Properties, Uses
3. What is the difference between Isopropyl and Ethyl AlcoholDifference Between Isopropyl and Ethyl Alcohol - Comparison Summary

What is Ethyl Alcohol

Ethyl alcohol, also called ethanol, has the molecular formula of CH3CH2OH. It has two carbon atoms, six hydrogens, and one oxygen. It is a colorless liquid with a pleasant smell. It is produced by either alcoholic fermentation or by reacting ethane with steam. Sugars from plants are fermented using zymase enzyme to obtain this. Ethanol has a melting point of -115 ̊C and a boiling point of 78 ̊C. Ethanol is highly soluble in water due to its polarity. Therefore, it is often available as an azeotropic mixture with water. Ethanol which is 100% free of water is called absolute ethanol. Ethanol is highly flammable and if heating for any experiment purposes, a water bath has to be used.

Ethanol is used worldwide as an intoxicating beverage. It is used as a solvent for perfume, biological specimen preservative, and a disinfectant in addition to its use in varnish manufacturing. It is also used as a biofuel which is often used as an additive to gasoline.

Even though ethanol is drinkable, if the level of ethanol in bloodstream exceeds 5% it can cause harmful effects. These harmful effects include vision impairment, behavioral changes or unconsciousness.

Ethanol is a primary alcohol. The –OH group is attached to the 1st Carbon of the chain. Due to this, ethanol is converted to an aldehyde when oxidized. This is the process which occurs in the liver. Ethanol is converted to acetaldehyde in the liver, which is quite harmful.

Difference Between Isopropyl and Ethyl Alcohol

Figure 1: Structural Formula of Ethyl Alcohol

What is Isopropyl Alcohol

Isopropyl alcohol is known as 2-propanol as well and is an isomer of propanol. Isopropyl alcohol has three carbons 8 hydrogens and one oxygen in its structure. Its molecular formula is CH3CHOHCH3. Being a polar compound, isopropyl alcohol too is miscible with water. Isopropyl alcohol is produced by indirect hydration of propylene and a method called strong acid process. The melting point of isopropyl alcohol is -89.5  ̊C and the boiling point is 82.4  ̊C. Isopropyl alcohol is a flammable liquid.

Uses of isopropyl alcohol are numerous. It is used in great quantities for the manufacturing of acetone. This alcohol is a good solvent for natural products such as oils, waxes, pectin, kelp and gums. This is also a good disinfectant and is used for medicinal cleaning purposes. Due to its dissolving properties and high volatility, isopropyl alcohol is used to clean electrical equipment.

Isopropyl alcohol can be harmful if ingested in sufficient quantities. The ingestion is mainly by inhalation. Short-term exposure can cause irritation in eyes and nose and depression in the central nervous system, causing nausea or unconsciousness.

Isopropyl alcohol is a secondary alcohol as the –OH group is attached to the 2nd carbon of the chain. Oxidation of this produces acetone. Isopropyl alcohol is commonly known as rubbing alcohol.

Main Difference - Isopropyl vs Ethyl Alcohol

Figure 2: Ball-and-stick model of Isopropyl

Difference Between Isopropyl and Ethyl Alcohol

Molecular Formula

Isopropyl: Isopropyl has the molecular formula of CH3CHOHCH3

Ethyl Alcohol: Ethyl Alcohol has the molecular formula of CH3CH2OH. 

Category

Isopropyl: Isopropyl is a secondary alcohol since -OH is attached to the 2nd carbon. 

Ethyl Alcohol: Ethyl alcohol is a primary alcohol since -OH is attached to the 1st carbon. 

Physical Properties 

Isopropyl: Boiling point -82.4  ̊C and Melting point is -89.5  ̊C.

Ethyl Alcohol: Boiling point is 78  ̊C and Melting point is -115  ̊C.

Drinkability 

Isopropyl: This is used as a beverage. 

Ethyl Alcohol: This is not drinkable. 

Uses 

Isopropyl: It is used as a solvent, disinfectant, and a cleaning agent.

Ethyl Alcohol: It is used as a solvent, disinfectant, biological specimen preservative, etc.

Conclusion 

The difference between Isopropyl and Ethyl Alcohol is mainly due to their different chemical structures – Ethyl alcohol has 2 carbons whereas isopropyl alcohol has three carbons. The –OH group of ethyl alcohol is attached to the first carbon of the chain and is called a primary alcohol. On the contrary, –OH group of isopropyl alcohol is attached to the second carbon and is known as a secondary alcohol. Boiling and melting points of the alcohols are slightly different.

Due to their structural differences, both alcohols give different products after oxidation. Ethyl alcohol yield acetaldehyde whereas isopropyl alcohol yields acetone. This is due to the different positions the –OH groups have attached. Ethyl alcohol can be used as a beverage whereas isopropyl alcohol is clearly not drinkable.

Reference:
1. “Ethanol.” Infoplease. N.p., n.d. Web. 16 Feb. 2017.
2. “Isopropanol | (CH3)2CHOH .” National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 16 Feb. 2017.
3. “What is isopropanol used for?” Reference.Com. N.p., n.d. Web. 16 Feb. 2017.

Image Courtesy:
1. “Ethanol-2D-flat”By Benjah-bmm27 – Own work  (Public Domain) via
2. “Propan-2-ol-3D-balls” By Jynto (talk) – Own work- This chemical image was created with Discovery Studio Visualizer. (CC0) via

About the Author: Pabasara

Pabasara posses a Bachelor's Degree in Chemistry and is reading for M.Phil. in Chemistry. She has working experience in both academic and industry environments.

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