Difference Between Propan-1-ol and Propan-2-ol

Main Difference – Propan-1-ol vs Propan-2-ol

Alcohols are chemical compounds that are categorized as organic compounds due to the presence of carbon and hydrogen atoms. Apart from carbon and hydrogen, alcohols contain oxygen atoms as well. The general formula of an alcohol is R-OH in which R is an alkyl group. Therefore, the simplest alcohol is methanol. Here, a methyl group is bonded to a hydroxyl (-OH) group. Alcohols are named according to the number of carbon atoms present in the compound and the position of the hydroxyl group. Propanol is an alcohol consist of three carbon atoms bonded to each other forming the backbone of the molecule. According to the position of the hydroxyl group on this carbon backbone, there are two types of propanol molecules named as propan-1-ol and propan-2-ol. The main difference between propan-1-ol and propan-2-ol is that the hydroxyl group of propan-1-ol is attached to the terminal carbon of the molecule whereas the hydroxyl group of the propan-2-ol is attached to the middle carbon of the molecule.

Key Areas Covered

1. What is Propan-1-ol
– Definition, Chemical Properties and Structure
2. What is Propan-2-ol
– Definition, Chemical Properties, Uses
3. What are the Similarities Between Propan-1-ol and Propan-2-ol
– Outline of Common Features
4. What is the Difference Between Propan-1-ol and Propan-2-ol
– Comparison of Key Differences

Key Terms: Alcohol, Alkyl Group, Carbon, Carbon Backbone, Hydroxyl Group, Isopropyl Alcohol, Oxygen Atom, Propanol

What is Propan-1-ol

Propan-1-ol is an alcohol having the chemical formula CH₃CH₂CH₂OH. The molar mass of this alcohol is 60.1 g/mol. At room temperature and pressure, propan-1-ol is a colorless liquid. It has a mild-alcoholic odor and a characteristic fruity flavor. The melting point of propan-1-ol is -126.1 °C and the boiling point is 97.2 °C.

When considering the chemical structure of propan-1-ol, it has three carbon atoms bonded to each other forming the backbone of the molecule. Since the compound is saturated having no double bonds or triple bonds, all carbon atoms comprise four covalent bonds around them. One of the terminal carbon atoms is bonded to a hydroxyl group (-OH). All other bonds are C-H bonds and C-C bonds. Hence it is a primary alcohol.

Difference Between Propan-1-ol and Propan-2-ol

Figure 1: Chemical Structure of Propan-1-ol

Propan-1-ol is produced by oxidation of aliphatic hydrocarbons. This compound is formed during fermentation processes, but in trace amounts. Propan-1-ol is used as a solvent in industries such as pharmaceutical industry. Apart from that, this alcohol is suitable for use as an engine fuel due to its high octane number.

What is Propan-2-ol

Propan-2-ol is an alcohol having the chemical formula CH₃CH(OH)CH₃. It is a secondary alcohol. The common name for Propan-2-ol is isopropyl alcohol. Propan-2-ol is the IUPAC name. The molar mass of the compound is 60.1 g/mol. The melting point of Propan-2-ol is −89 °C, and the boiling point is 82.6 °C. It is a colorless liquid at room temperature and pressure. Propan-2-ol has a pleasant odor and a slightly bitter taste.

When considering the chemical structure of Propan-2-ol, it has three carbon atoms bonded to each other, forming the carbon backbone of the molecule. This is a saturated compound having no double or triple bonds. The hydroxyl group (-OH) is attached to the middle carbon of the molecule. All the other bonds are C-H and C-C bonds.

Main Difference - Propan-1-ol vs Propan-2-ol

Figure 2: Chemical Structure of Propan-2-ol

Propan-2-ol can be oxidized to acetone. Acetone is the corresponding ketone compound to this aldehyde compound. Propan-2-ol can be produced by several methods such as indirect hydration (reaction of propane with sulfuric acid to form a mixture of sulfate esters which then undergo hydrolysis to form isopropyl alcohol), direct hydration (reaction between propane and water at high pressure in the presence of an acidic catalyst to yield this alcohol) and hydrogenation of acetone (hydrogenation of crude propane in the presence of suitable metal catalysts).

Propan-2-ol is used as a solvent for nonpolar compounds. Since it is highly volatile, it has different uses. In medical applications, isopropyl alcohol is used as a component in many products such as hand sanitizers, rubbing alcohol, etc. Propan-2-ol is also used as a fuel additive.

Similarities Between Propan-1-ol and Propan-2-ol

Propan-1-ol and Propan-2-ol are two alcohols.
Both are composed of three carbon atoms.
Both have the general chemical formula.
Both are colorless liquids at room temperature.
Both have the same molar mass.

Definition

Propan-1-ol: Propan-1-ol is an alcohol having the chemical formula CH₃CH₂CH₂OH.

Propan-2-ol: Propan-2-ol is an alcohol having the chemical formula CH₃CH(OH)CH₃.

Position of Hydroxyl Group

Propan-1-ol: The hydroxyl group of propan-1-ol is attached to the terminal carbon of the molecule.

Propan-2-ol: The hydroxyl group of the propan-2-ol is attached to the middle carbon of the molecule.

Melting Point

Propan-1-ol: The melting point of propan-1-ol is -126.1 °C.

Propan-2-ol: The melting point of Propan-2-ol is −89 °C

Boiling Point

Propan-1-ol: The boiling point of propan-1-ol is 97.2 °C.

Propan-2-ol: The boiling point of propan-2-ol is 82.6 °C.

Uses

Propan-1-ol: Propan-1-ol is used as a solvent, fuel, etc.

Propan-2-ol: Propan-2-ol is used as a solvent for nonpolar compounds, as a fuel additive, etc.

Conclusion

Propanol is an alcohol. It has three carbon atoms bonded to each other, forming the carbon backbone of the molecule. According to the position where the hydroxyl group is attached to this backbone, there are two types of propanol molecules as propan-1-ol and propan-2-ol. The main difference between propan-1-ol and propan-2-ol is that the hydroxyl group of propan-1-ol is attached to the terminal carbon of the molecule whereas the hydroxyl group of the propan-2-ol is attached to the middle carbon of the molecule.

Reference:

1. “1-propanol.” National Center for Biotechnology Information. PubChem Compound Database. Accessed December 30, 2017. Available here.
2. “Isopropanol.” National Center for Biotechnology Information. PubChem Compound Database. Accessed December 30, 2017. Available here.
3. “1-Propanol.” Wikipedia. December 23, 2017. Accessed December 30, 2017. Available here.

Image Courtesy:

1. “Propan-1-ol Lewis” By NEUROtiker ⇌ – Own work (Public Domain) via Commons Wikimedia
2. “Propan-2-ol displayed” By GKFX – Own work (Public Domain) via Commons Wikimedia