3-Methyl-1-butanol: Properties, Uses & Lab Guide

3-Methyl-1-butanol is a short-chain primary alcohol widely employed in molecular biology, organic synthesis, and industrial processes owing to its moderate polarity, low water miscibility, and availability in ultra-dry grades suitable for moisture-sensitive reactions.

IUPAC Name

3-Methylbutan-1-ol

Common Synonym

Isoamyl alcohol; Isopentyl alcohol

Molecular Formula

C₅H₁₂O

Molecular Weight

88.15 g/mol

Boiling Point

Approximately 131 °C at 760 mmHg

Key Grade Available

Ultra-dry solvent (anhydrous)

Aladdin SKU

M1521147

Physicochemical Properties

3-Methyl-1-butanol (isoamyl alcohol, CAS commonly referenced as 123-51-3) is a colorless, oily liquid with a characteristic fusel-oil odor. Its molecular formula is C₅H₁₂O and molecular weight is 88.15 g/mol. The compound is a primary alcohol with a branched carbon skeleton, giving it a boiling point of approximately 131 °C at atmospheric pressure and a melting point around −117 °C. It has limited miscibility with water and is freely miscible with common organic solvents such as ethanol, diethyl ether, and chloroform. The relatively low dielectric constant and moderate polarity make it a useful partitioning solvent. Its density is approximately 0.81 g/mL at 20 °C, and its refractive index is near 1.407.

When supplied as an ultra-dry (anhydrous) grade, the water content is rigorously controlled to very low levels (typically below 30 ppm by Karl Fischer titration), making it suitable for use in reactions sensitive to trace moisture, such as organometallic transformations, silylation reactions, and certain coupling chemistries.

Key Laboratory and Industrial Applications

Molecular Biology — DNA/RNA Extraction: One of the most widespread uses of isoamyl alcohol in the life sciences is its inclusion in chloroform:isoamyl alcohol (24:1) mixtures used during nucleic acid purification. The alcohol reduces foaming and helps achieve a clean phase separation between the aqueous and organic layers, removing proteins and lipids from nucleic acid preparations.

Organic Synthesis: 3-Methyl-1-butanol serves as a starting material or building block for the synthesis of isoamyl esters (e.g., isoamyl acetate, the characteristic banana fragrance compound), plasticizers, and other fine chemicals. It can also act as a reaction solvent for certain transformations, particularly when an alcohol with limited water miscibility is required.

Ultra-Dry Solvent Applications: As an anhydrous-grade reagent, 3-Methyl-1-butanol is employed in moisture-sensitive synthetic procedures, including organometallic reactions, Grignard-type setups, and acid chloride chemistry, where even trace water can quench reactive intermediates or reduce yields significantly.

Flavors and Fragrances Industry: Isoamyl alcohol is a natural constituent of fusel oil, a by-product of fermentation, and finds application as an intermediate in the synthesis of flavoring agents used in food and cosmetic formulations.

Ultra-Dry Solvent Grade: Handling and Storage

The ultra-dry (anhydrous) grade of 3-Methyl-1-butanol is packaged under inert atmosphere to minimize moisture ingress. Researchers should observe the following best practices:

• Storage: Store tightly sealed in a cool, well-ventilated area away from heat sources and open flames. Recommended storage temperature is typically room temperature or as specified on the product label.
• Handling: Use under an inert gas (nitrogen or argon) atmosphere when moisture exclusion is critical. Employ dry syringes or cannula transfer techniques to avoid atmospheric exposure.
• Container integrity: Once opened, re-seal promptly with appropriate closures (e.g., Sure/Seal or equivalent). Record the date of first opening and monitor water content periodically by Karl Fischer titration if the application demands rigorous anhydrous conditions.
• Waste disposal: Dispose of in accordance with local regulations for flammable organic solvents.

Always consult the Safety Data Sheet (SDS) before use. 3-Methyl-1-butanol is flammable (flash point approximately 43 °C) and should be handled away from ignition sources.

Purity, Grades, and Quality Specifications

Aladdin Scientific supplies 3-Methyl-1-butanol under SKU M1521147 as an ultra-dry solvent grade. Key quality attributes typically evaluated for this type of reagent include:

• Purity (GC): High-purity grades are verified by gas chromatography to confirm the proportion of the main component and identify potential organic impurities.
• Water content: Determined by Karl Fischer titration; ultra-dry grades target water levels typically ≤30 ppm, though buyers should confirm the exact specification on the current Certificate of Analysis (CoA).
• Appearance: Clear, colorless liquid, free of visible particles or turbidity.
• Refractive index and density: Routinely checked as identity and purity indicators.

Researchers requiring specific lot-level data such as exact purity percentage, water content, or spectroscopic data should request the Certificate of Analysis (CoA) for the purchased lot through Aladdin Scientific's product pages or customer service.

Frequently asked questions

What is the difference between standard-grade and ultra-dry 3-Methyl-1-butanol?

Standard-grade 3-Methyl-1-butanol may contain variable amounts of dissolved water, which is acceptable for many general applications such as extractions or routine organic reactions. Ultra-dry (anhydrous) grade is rigorously dried and packaged under inert atmosphere to achieve very low water content (typically ≤30 ppm), making it suitable for moisture-sensitive reactions including organometallic chemistry, silylation, and Grignard setups where trace water would compromise the reaction outcome.

How should I store ultra-dry 3-Methyl-1-butanol to maintain its anhydrous quality?

Store the sealed bottle in a cool, dry, well-ventilated location away from heat and ignition sources. After opening, work under inert gas (nitrogen or argon) and reseal promptly using the original or equivalent moisture-excluding closure. If the application requires strict anhydrous conditions, verify residual water content by Karl Fischer titration before use and record the date of first opening.

Can 3-Methyl-1-butanol be used for nucleic acid extraction, and what ratio with chloroform is recommended?

Yes, isoamyl alcohol (3-Methyl-1-butanol) is a standard component in nucleic acid purification protocols. It is most commonly combined with chloroform in a 24:1 (v/v) chloroform:isoamyl alcohol ratio. In this mixture, isoamyl alcohol reduces foaming during vortexing and promotes clean phase separation, facilitating removal of proteins and lipids from the aqueous nucleic acid phase. Researchers should follow their specific validated protocol for exact volumes and centrifugation conditions.

What safety precautions are required when handling 3-Methyl-1-butanol in the laboratory?

3-Methyl-1-butanol is a flammable liquid with a flash point of approximately 43 °C and should be kept away from open flames, sparks, and other ignition sources. Work in a well-ventilated fume hood, wear appropriate PPE including chemical-resistant gloves, safety glasses, and lab coat. Avoid prolonged inhalation of vapors. Consult the current Safety Data Sheet (SDS) provided by Aladdin Scientific for complete hazard information and emergency procedures before use.

References

1. Sigma-Aldrich / Merck product data and general chemical reference data for isoamyl alcohol (3-Methyl-1-butanol, CAS 123-51-3).
2. Sambrook J, Russell DW. Molecular Cloning: A Laboratory Manual. Cold Spring Harbor Laboratory Press. (Standard reference for chloroform:isoamyl alcohol 24:1 nucleic acid extraction protocol.)
3. Aladdin Scientific product listing: 3-Methyl-1-butanol, SKU M1521147, ultra-dry solvent grade.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.