The key difference between amyl alcohol and isoamyl alcohol is that amyl alcohol is a mixture of eight different isomers having the C5H12O chemical formula, whereas isoamyl alcohol is the most important isomer among them.
Typically, the term amyl alcohol is used to refer to a mixture of different isomers of C5H12O. However, sometimes we use this term to refer to pentan-1-ol specifically as a common term.
CONTENTS
1. Overview and Key Difference
2. What is Amyl Alcohol
3. What is Isoamyl Alcohol
4. Amyl Alcohol vs Isoamyl Alcohol in Tabular Form
5. Summary – Amyl Alcohol vs Isoamyl Alcohol
What is Amyl Alcohol?
Amyl alcohol is any of the eight alcohols having the chemical formula C5H12O. We can obtain a mixture of amyl alcohols from fusel alcohol. This mixture is also collectively known as amyl alcohol. It is useful as a solvent for the esterification process. This process produces amyl acetate and other important products as well. Without any specification, we use 1-pentanol as amyl alcohol as a common term.
Figure 01: 1-Pentanol Chemical Structure
The names of the structural isomers that exist for the chemical formula C5H12O include 1-pentanol, 2-methylbutan-1-ol, 3-methylbutan-1-ol, 2,2-dimethylpropan-1-ol, pentan-2-ol, 3-methylbutan-2-ol, pentan-3-ol, and 2-methylbutan-2-ol. Among these substances, three alcohols are optically active (2-methyl-1-butanol, 2-pentanol, and 3-methyl-2-ol).
What is Isoamyl Alcohol?
Isoamyl alcohol is the most important amyl alcohol, having the chemical formula C5H12O. It occurs as a colorless liquid and is one of the several isomers of amyl alcohol. We can name this compound as isopentyl alcohol, isopentanol, or 3-methyl-butan-1-ol.
This liquid substance has a disagreeable odor in high concentrations. It has a density of 0.81 g/cm3. Its melting point is -117 degrees Celsius, whereas the boiling point is 131.1 degrees Celsius. It is slightly soluble in water and very soluble in acetone, diethyl ether, and ethanol. We can find this substance as a component of the aroma of Tuber melanosporum black truffle. Moreover, it has been identified as a pheromone (chemical) used by hornets (to attract other members of the hive to attack).
Figure 02: Chemical Structure of Isoamyl Alcohol
We can extract isoamyl alcohol from fusel oil via two methods: shaking with string brine solution and separating the oil from the brine layer or by distilling it and collecting the fraction that is boiling between 125 and 140 degrees Celsius. If we need further purification, we can do it by shaking the product with hot limewater, followed by separating the oily layer and drying the product with calcium chloride, thereafter distilling the mixture to collect the fraction boiling between 128 and 132 degrees Celsius.
Typically, this liquid is flammable and moderately toxic, thus hazardous. Its flash point is at 43 degrees Celsius, and the auto-ignition temperature is around 350 degrees Celsius.
When considering the synthesis of this substance, we can synthesize it rather than extracting it from fusel oil. This can be done via condensation of isobutene and formaldehyde, which gives isoprenol, and then we can perform hydrogenation. This gives a colorless liquid with a density of around 0.824 g/cm,3 which boils at 131.6 degrees Celsius and easily dissolves in organic solvents.
There are some important uses of isoamyl alcohol, including the synthesis of banana oil, as an ingredient of Kovac’s reagent (this is useful for the bacterial diagnostic indole test). Moreover, we can use it as an antifoaming agent in the chloroform isoamyl alcohol reagent. In addition, this substance is important in phenol-chloroform extraction, which is mixed with the chloroform for the further inhibition of RNase activity.
What is the Difference Between Amyl Alcohol and Isoamyl Alcohol?
Amyl alcohol and isoamyl alcohol are important terms in some organic synthesis processes. The key difference between amyl alcohol and isoamyl alcohol is that amyl alcohol is a mixture of eight different isomers of C5H12O chemical formula, whereas isoamyl alcohol is the most important isomer among them.
The following table summarizes the difference between amyl alcohol and isoamyl alcohol.
Summary – Amyl Alcohol vs Isoamyl Alcohol
Amyl alcohol is a collective name that represents eight related chemical compounds. Isoamyl alcohol is one of those structures. The key difference between amyl alcohol and isoamyl alcohol is that amyl alcohol is a mixture of eight different isomers of C5H12O chemical formula, whereas isoamyl alcohol is the most important isomer among them.
Reference:
1. “Bakery Processes, Chemical Leavening Agents.” Online Library Wiley.
Image Courtesy:
1. “Pentan-1-ol-2D-skeletal” (Public Domain) via Commons Wikimedia
2. “Isoamyl alcohol” By Arrowsmaster – Own work (CC BY-SA 3.0) via Commons Wikimedia