Difference Between Isopropyl and Ethyl Alcohol

Difference – Isopropyl vs Ethyl Alcohol

The main difference between isopropyl and ethyl alcohol is the difference in their chain length.

Isopropyl and Ethyl Alcohol are two organic compounds. The primary functional group of these alcohols is –OH group. The naming of these alcohols is according to the number of carbon atoms they have. Ethyl alcohol has got two carbon atoms whereas isopropyl alcohol has got three carbon atoms.

Key Areas Covered

1. What is Ethyl Alcohol
      – Structure, Molecular Formula, Properties, Uses
2. What is Isopropyl Alcohol
      – Structure, Molecular Formula, Properties, Uses
3. What is the difference between Isopropyl and Ethyl Alcohol
      – Comparison of Key Differences

Key Terms

2-Propanol, Ethanol, Ethyl Alcohol, Isopropyl Alcohol, Rubbing Alcohol

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. Also, the melting point of it is -115 ̊C and the boiling point is 78 ̊C. Ethanol is highly soluble in water due to its polarity. Therefore, it is often available as an azeotropic mixture with water. Furthermore, absolute ethanol refers to the ethanol that is 100% free of water. Another property of ethanol is that it is highly flammable, therefore, when heating for any experiment purposes, has to use a water bath.

Moreover, the production of it is via either alcoholic fermentation or by reacting ethane with steam. Sugars from plants are fermented using zymase enzyme to obtain this. Considering the usage, the common use of it worldwide is as a intoxicating beverage. However, if the level of ethanol in bloodstream exceeds 5% it can cause harmful effects. These harmful effects include vision impairment, behavioral changes or unconsciousness. Importantly, ethanol is a primary alcohol. Thus, the –OH group is attached to the 1^st Carbon of the chain. Due to this, when oxidized, it converts as an aldehyde. So, a similar process occurs in the liver too. Consequently, ethanol converts into acetaldehyde in the liver, which is quite harmful.

In addition to the above usage, it also works as a solvent for perfume, biological specimen preservative, and a disinfectant in addition to its use in varnish manufacturing. Besides, it is a biofuel and often used as an additive to gasoline.

Difference Between Isopropyl and Ethyl Alcohol

Figure 1: Structural Formula of Ethyl Alcohol

What is Isopropyl Alcohol

Isopropyl alcohol, also known as 2-propanol or rubbing alcohol, is an isomer of propanol. It has three carbons 8 hydrogens and one oxygen in its structure. Its molecular formula is CH₃CHOHCH₃. Besides, it is a secondary alcohol as the –OH group is attached to the 2^nd carbon of the chain. In addition, oxidation of this produces acetone. The production of it is via indirect hydration of propylene and by strong acid process. Looking at their properties, its melting point is -89.5 ̊C and boiling point is 82.4 ̊C. Being a polar compound, it is miscible with water. And, this alcohol too is a flammable liquid.

Considering the usage, the uses of isopropyl alcohol are numerous. It is used in great quantities for the manufacturing of acetone. Also, it is a good solvent for natural products such as oils, waxes, pectin, kelp, and gums. Furthermore, it is a good disinfectant; thus, used for medicinal cleaning purposes. Due to its dissolving properties and high volatility, people use it to clean electrical equipmentas well.

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

Main Difference - Isopropyl vs Ethyl Alcohol

Figure 2: Ball-and-stick model of Isopropyl

Molecular Formula

Isopropyl has the molecular formula of CH₃CHOHCH₃.

Ethyl Alcohol has the molecular formula of CH₃CH₂OH.

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: Not drinkable.

Ethyl Alcohol: Commonly, used as a beverage.

Uses

Isopropyl: A solvent, disinfectant, and a cleaning agent.

Ethyl Alcohol: 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 therefore, it is a primary alcohol. On the contrary, –OH group of isopropyl alcohol is attached to the second carbon and thus, it is a secondary alcohol. Also, the boiling and melting points of the alcohols are slightly different. Furthermore, due to their structural differences, both alcohols give different products after oxidation. Ethyl alcohol yield acetaldehyde whereas isopropyl alcohol yields acetone. It is due to the different positions the –OH groups. Moreover, people consume ethyl alcohol as a beverage, but 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 Commons Wikimedia
2. “Propan-2-ol-3D-balls” By Jynto (talk) – Own work- This chemical image was created with Discovery Studio Visualizer. (CC0) via Commons Wikimedia