Isoamyl alcohol structure, properties, uses and risks

4562
David Holt

The isoamyl alcohol is an organic compound whose formula is (CH3)twoCHCHtwoCHtwoOH. Chemically speaking it is a branched primary alcohol, and constitutes one of the isomers of pentanol, called amyl alcohols (C5H12OR).

Like many low molecular weight alcohols, it is a colorless liquid at room temperature. This allows and facilitates its use as a solvent for different applications; even more so, when it does not exert too many negative effects on the ecosystem after being disposed of.

Isoamyl alcohol molecule. Source: Claudio Pistilli from Wikipedia.

Although it is an intermediate material in the synthesis of amyl acetate for the production of artificial banana fragrances, its own smell is unpleasant and similar to that of pears..

In addition to serving as a solvent for multiple biological substances, and as an intermediate in the synthesis of other acetates, it reduces the surface tension of certain industrial formulations, preventing the formation of foams. Therefore, it is used in microemulsified systems.

Regarding its natural origin, isoamyl alcohol has been found in the pheromones of hornets, and in black truffles, a type of fungi located in southeastern Europe.

Article index

  • 1 Structure of isoamyl alcohol
    • 1.1 Intermolecular interactions
  • 2 Properties
    • 2.1 Physical appearance
    • 2.2 Smell and taste
    • 2.3 Molar mass
    • 2.4 Density
    • 2.5 Vapor density
    • 2.6 Vapor pressure
    • 2.7 Boiling point
    • 2.8 Melting point
    • 2.9 Flash point
    • 2.10 Autoignition temperature
    • 2.11 Solubility
    • 2.12 Viscosity
    • 2.13 Surface tension
    • 2.14 Refractive index
    • 2.15 Heat capacity
  • 3 Uses
    • 3.1 Raw material
    • 3.2 Fragrances
    • 3.3 Defoamer
    • 3.4 Extractions
  • 4 Risks
    • 4.1 Storage and reactivity
    • 4.2 Health
  • 5 References

Structure of isoamyl alcohol

The upper image shows the isoamyl alcohol molecule represented with a spheres and bars model. To the right of it, the reddish sphere corresponds to the oxygen atom of the OH group, characteristic for all alcohols; while on the left is the carbon skeleton with a methyl group, CH3, branching structure.

From a molecular point of view, this compound is dynamic because it has atoms with sp hybridizations3, facilitating the rotation of your links; as long as it doesn't cause the OH and CH to eclipse3.

It is also worth mentioning its amphiphilic characteristic: it has an apolar or hydrophobic end, made up of the chain (CH3)twoCHCHtwoCHtwo-, and a polar or hydrophilic head, the OH group. This definition of two specific areas of different polarities makes this alcohol a surfactant; and hence its application for microemulsions.

Intermolecular interactions

Given the presence of the OH group, the isoamyl alcohol molecule exhibits a permanent dipole moment. Consequently, the dipole-dipole forces manage to bind their molecules, responsible for the physical and measurable properties of the liquid, as well as its odor..

Although the branching of the main chains decreases the effective interactions between the molecules, the hydrogen bonds in this alcohol compensate for this decrease, causing the liquid to boil at 131 ° C, a temperature above the boiling point of water..

Not the same happens with its solid or "ice", which melts at -117 ° C, indicating that its intermolecular interactions are not strong enough to keep its molecules in order; especially if the CH group3 that branches the main chain prevents better contact between the molecules.

Properties

Physical appearance

Colorless liquid.

Smell and taste

Gives off an unpleasant pear-like odor and has a pungent taste.

Molar mass

88.148 g / mol.

Density

0.8104 g / mL at 20 ° C. It is therefore less dense than water.

Vapor density

It is 3.04 times denser than air.

Vapor pressure

2.37 mmHg at 25 ° C.

Boiling point

131.1 ° C.

Melting point

-117.2 ° C.

ignition point

43 ° C (closed cup).

Autoignition temperature

340 ° C.

Solubility

It is relatively soluble in water: 28g / L. This is because the highly polar molecules in water have no special affinity for the carbon chain of isoamyl alcohol. If they were mixed, two phases would be observed: a lower one, corresponding to water, and a higher one, that of isoamyl alcohol..

In contrast, it is much more soluble in less polar solvents such as: acetone, diethyl ether, chloroform, ethanol, or glacial acetic acid; and even in petroleum ether.

Viscosity

3,738 cP at 25 ° C.

Surface tension

24.77 dynes / cm at 15 ° C.

Refractive index

1.4075 at 20 ° C.

Heat capacity

2,382 kJ / gK.

Applications

Raw material

Other esters, thiophene, and drugs such as amyl nitrite, Validol (menthyl isovalerate), Bromisoval (bromovalerylurea), Corvalol (a valerian tranquilizer), and Barbamil (amobarbital) can be synthesized from isoamyl alcohol..

Fragrances

In addition to being used for the synthesis of amyl acetate, which has a banana aroma, other fruit fragrances such as apricot, oranges, plum, cherry and malt are also obtained from it. Therefore, it is a necessary alcohol in the production of many edible or cosmetic products..

Defoamer

By reducing surface tension, it promotes its use in microemulsified systems. Practically, it avoids the accelerated formation of bubbles, reducing them in size until they break.

It also helps to better define the interface between the aqueous and organic phases during extractions; for example, phenol-chloroform is added to the extractor mixture in a ratio of 25: 24: 1. This technique is intended for DNA extraction.

Extractions

Isoamyl alcohol also makes it possible to extract fats or oils from different samples, for example from milk. Likewise, it dissolves paraffin wax, inks, gums, lacquers and cellulose esters.

Continuing with the extractions, with it phosphoric acid can be obtained from solutions of nitrates of iron phosphate minerals.

Risks

Storage and reactivity

Like any liquid that gives off odors, it can represent an imminent fire risk if the place where it is stored raises its temperature too high, even more if there is already a source of heat..

Under these conditions, it simply acts as a fuel, fueling the flames and even exploding its container. When burning, it releases vapors that can affect health and cause suffocation.

Other causes that isoamyl alcohol catches fire is to mix it or make it react with substances such as: perchlorates, peroxides, bromine, fluorine, metal hydrides, strong acids, aliphatic amines, etc..

Health

In contact with the skin, it can irritate and dry it out. Symptoms, however, are more serious if inhaled for too long (cough, burns to nose, throat, and lungs), or if swallowed (headache, nausea, diarrhea, vomiting, dizziness, and loss of consciousness)..

And finally, when it spills into the eyes, it irritates them and can even irreversibly damage them. Fortunately, its "alcoholic pear" smell allows it to be detected in the event of a leak or spill; in addition to this, it is a compound that must be handled with respect.

References

  1. Morrison, R. T. and Boyd, R, N. (1987). Organic Chemistry. 5th Edition. Editorial Addison-Wesley Interamericana.
  2. Carey F. (2008). Organic Chemistry. (Sixth edition). Mc Graw Hill.
  3. Graham Solomons T.W., Craig B. Fryhle. (2011). Organic Chemistry. Amines. (10th edition.). Wiley plus.
  4. Wikipedia. (2019). Isoamyl alcohol. Recovered from: en.wikipedia.org
  5. National Center for Biotechnology Information. (2019). Isoamyl alcohol. PubChem Database. CID = 31260. Recovered from: pubchem.ncbi.nlm.nih.gov
  6. Zhang Yu & Muhammed Mamoun. (September 17, 2008). Extraction of phosphoric acid from nitrate solutions with isoamyl alcohol. Solvent Extraction and Ion Exchange Volume 6, 1988 - Issue 6. doi.org/10.1080/07366298808917973
  7. New Jersey Department of Health. (2008). Isoamyl alcohol. [PDF]. Recovered from: nj.gov
  8. Kat Chem. (2019). Isoamyl alcohol. Recovered from: kat-chem.hu
  9. Chemoxy International Ltd. (s.f.). Isoamyl alcohol. Recovered from: chemoxy.com

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