Ethyl Isobutyrate: Properties, Uses & Lab Guide

Ethyl Isobutyrate is a short-chain aliphatic ester widely used as a reference standard, synthetic building block, and flavour-fragrance ingredient in both academic research and industrial applications.

Chemical Name

Ethyl Isobutyrate (Ethyl 2-methylpropanoate)

CAS Number

97-62-1

Molecular Formula

C₆H₁₂O₂

Molecular Weight

116.16 g/mol

Appearance

Colourless, mobile liquid with a fruity, rum-like odour

Boiling Point

~110 °C at 760 mmHg

Density

~0.869 g/mL at 20 °C

Aladdin SKU

E156123

Chemical Identity and Physicochemical Properties

Ethyl Isobutyrate, systematically named ethyl 2-methylpropanoate, is the ethyl ester of isobutyric acid. It carries the CAS registry number 97-62-1 and the molecular formula C₆H₁₂O₂ (MW 116.16 g/mol). At ambient temperature it is a colourless, highly mobile liquid characterised by a pleasant, fruity odour reminiscent of rum and pineapple, making it organoleptically distinctive among low-molecular-weight esters.

Key physicochemical parameters include a boiling point of approximately 110 °C at atmospheric pressure, a density of roughly 0.869 g/mL at 20 °C, and a refractive index (n²⁰D) of approximately 1.387. The compound is miscible with common organic solvents such as ethanol, diethyl ether, and acetone, but has limited solubility in water, consistent with its log P value of approximately 1.7. Its relatively low boiling point and vapour pressure contribute to rapid volatilisation under open-bench conditions, an important consideration for both analytical work and safe handling.

The ester functional group renders Ethyl Isobutyrate susceptible to hydrolysis under both acidic and basic aqueous conditions, regenerating isobutyric acid and ethanol. This reactivity must be considered when designing reaction conditions or formulating solutions intended for long-term storage.

Synthesis and Manufacturing Background

Ethyl Isobutyrate is classically prepared by Fischer esterification: the acid-catalysed condensation of isobutyric acid with ethanol in the presence of a mineral acid catalyst such as sulfuric acid or p-toluenesulfonic acid. The reaction is reversible and equilibrium-driven; excess ethanol or continuous removal of water (e.g., by azeotropic distillation or molecular sieves) is employed to push conversion toward the product. Purification is typically achieved by fractional distillation.

On an industrial scale, the compound may also be produced via transesterification, enzymatic esterification using lipases, or continuous reactive distillation processes designed to achieve high purity and yield with minimal waste. Enzyme-mediated synthesis is particularly attractive for the production of food- and flavour-grade material because it avoids harsh acidic conditions and can operate at mild temperatures.

For research purposes, commercially sourced Ethyl Isobutyrate is available from Aladdin Scientific (SKU E156123) at defined purity grades, eliminating the need for in-house synthesis and providing the consistency and traceability required for analytical and formulation work.

Applications in Research and Industry

Flavour and Fragrance Chemistry. Ethyl Isobutyrate is recognised as a naturally occurring volatile constituent of numerous fruits including pineapple, strawberry, and certain grape varieties. It is extensively used in the food and fragrance industries as a flavourant to impart fruity top notes to confectionery, beverages, and personal care products. In research settings, it serves as an authentic reference standard for headspace GC, SPME-GC/MS, and electronic nose studies aimed at characterising fruit aroma profiles or monitoring fermentation processes.

Organic Synthesis. As a reactive ester, Ethyl Isobutyrate is a versatile building block in synthetic organic chemistry. It participates in Claisen condensation reactions, nucleophilic acyl substitution with organometallic reagents (e.g., Grignard reagents), and reduction to the corresponding alcohol using DIBAL-H or LiAlH₄. These transformations provide access to branched-chain alcohols, ketones, and β-keto esters of pharmaceutical and agrochemical relevance.

Analytical Reference Standard. High-purity Ethyl Isobutyrate is used to calibrate GC detectors, validate HPLC methods, and prepare certified standard solutions for food authenticity testing, environmental monitoring of volatile organic compounds (VOCs), and quality-control programmes in the flavour industry.

Biochemical and Metabolic Studies. The compound and its hydrolysis products are of interest in studies of ester metabolism, lipase substrate specificity, and olfactory receptor activation research, where defined-purity material is essential for reproducible dose–response measurements.

Safe Handling, Storage, and Regulatory Considerations

Flammability. Ethyl Isobutyrate is a flammable liquid (flash point approximately 13 °C, closed cup), classified under GHS Flammable Liquids Category 3 (or Category 2 in some classifications). It must be kept away from open flames, sparks, and hot surfaces. All work should be performed in a well-ventilated fume hood, and explosion-proof electrical equipment should be used where applicable.

Health Hazards. The vapour is an irritant to the eyes, skin, and respiratory tract at elevated concentrations. Prolonged or repeated skin contact may cause defatting and dermatitis. Personal protective equipment (PPE) including chemical-resistant gloves, safety spectacles, and a lab coat should be worn. In the event of skin or eye contact, flush immediately with copious water and seek medical advice if irritation persists.

Storage. Store in tightly sealed containers in a cool (below 25 °C), dry, well-ventilated area away from sources of ignition, oxidising agents, and strong bases or acids that could accelerate hydrolysis. Amber glass bottles are recommended to minimise photodegradation. Containers should be bonded and grounded during transfer to prevent static discharge.

Disposal. Dispose of waste material in accordance with local, regional, and national regulations governing flammable organic solvents. Do not pour down the drain or allow to enter waterways.

Regulatory Status. Ethyl Isobutyrate is listed as GRAS (Generally Recognised As Safe) by the US FDA for use as a flavouring agent (21 CFR), and is permitted by the European flavouring regulation (EC No 1334/2008). Researchers should verify the current regulatory status for their specific application and jurisdiction.

Quality, Purity, and Sourcing Guidance

For most research applications, the purity grade of Ethyl Isobutyrate must be matched to the analytical or synthetic objective. Analytical-grade or high-purity (≥98–99 % GC) material is required for calibration standards, flavour reference panels, and kinetic or mechanistic studies where even trace impurities (e.g., residual isobutyric acid, diethyl ether, or water) could skew results.

When procuring Ethyl Isobutyrate, researchers should request a Certificate of Analysis (CoA) confirming GC purity, water content (Karl Fischer), refractive index, and density. Lot-to-lot consistency is especially important in longitudinal studies or multi-site collaborative projects.

Aladdin Scientific offers Ethyl Isobutyrate under SKU E156123, providing reliable supply with documented quality data. Researchers and procurement teams are encouraged to contact Aladdin Scientific's technical support for guidance on appropriate grade selection, bulk ordering options, and current availability.

Frequently asked questions

What is the typical use of Ethyl Isobutyrate in a research laboratory?

Ethyl Isobutyrate is used primarily as a flavour reference standard in GC and GC/MS aroma analysis, as a synthetic building block for preparing branched-chain alcohols and β-keto esters via Claisen condensation or organometallic addition, and as a substrate in lipase activity assays. Its well-characterised physicochemical properties also make it suitable for validating olfactory receptor or electronic nose systems.

How should Ethyl Isobutyrate be stored to maintain its stability?

Store Ethyl Isobutyrate in tightly sealed amber glass containers at temperatures below 25 °C in a cool, dry, well-ventilated area away from ignition sources, strong oxidisers, and aqueous acid or base. Under these conditions the compound is stable for extended periods. Avoid repeated freeze–thaw cycles, and check the CoA for the supplier-recommended shelf life.

Is Ethyl Isobutyrate safe to use on the open bench?

No. Because Ethyl Isobutyrate has a low flash point (approximately 13 °C), it presents a significant fire and explosion risk when used on an open bench near ignition sources. All handling should take place inside a certified fume hood with explosion-proof ventilation, and appropriate PPE (gloves, eye protection) must be worn at all times.

What analytical techniques are best suited for characterising Ethyl Isobutyrate in a mixture?

Gas chromatography (GC-FID or GC/MS) is the method of choice for quantitation and identity confirmation owing to the compound's volatility and good chromatographic behaviour on non-polar or slightly polar capillary columns. Headspace-SPME coupled to GC/MS is particularly powerful for trace-level determination in food or fermentation matrices. NMR spectroscopy (¹H and ¹³C) provides definitive structural confirmation of the purified material.

Can Ethyl Isobutyrate be used as a food-grade flavouring ingredient?

Ethyl Isobutyrate is listed as GRAS by the US FDA and is permitted under European flavouring regulation EC No 1334/2008. However, material intended for food or consumer product use must meet food-grade purity specifications and full regulatory traceability requirements. Research-grade material from Aladdin Scientific (SKU E156123) is intended for laboratory use only; researchers requiring food-grade supply should consult the relevant regulatory guidance and source accordingly.

References

1. Burdock, G.A. (Ed.) Fenaroli's Handbook of Flavor Ingredients, 6th edn. CRC Press, Boca Raton, FL (2010).
2. US FDA. 21 CFR Part 172 — Food Additives Permitted for Direct Addition to Food for Human Consumption; Flavouring Agents and Related Substances.
3. European Parliament and Council. Regulation (EC) No 1334/2008 on flavourings and certain food ingredients with flavouring properties. Official Journal of the European Union (2008).
4. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 5th edn. Wiley-Interscience, New York (2001). [Fischer esterification and ester reactivity]

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