3-Butenoic Acid: Properties, Uses & Lab Applications

3-Butenoic Acid is a short-chain, terminal alkene-bearing carboxylic acid widely employed in organic synthesis, polymer chemistry, and biochemical research as a versatile reactive building block.

IUPAC Name

But-3-enoic acid

Common Synonym

Vinylacetic acid

Molecular Formula

C₄H₆O₂

Molecular Weight

86.09 g/mol

Key Functional Groups

Terminal alkene (vinyl) and carboxylic acid

CAS Number

625-38-7

Aladdin SKU

B152769

Chemical Identity and Physical Properties

3-Butenoic acid (CAS 625-38-7), also known as vinylacetic acid or but-3-enoic acid, is a four-carbon α,β-unsaturated carboxylic acid in which the double bond is located at the terminal (3,4) position rather than conjugated with the carbonyl group. This positional distinction separates it from crotonic acid (but-2-enoic acid) and gives it a unique reactivity profile.

The compound appears as a colorless to pale yellow liquid at room temperature with a pungent, acrid odor characteristic of low-molecular-weight unsaturated acids. Its dual functionality — a nucleophilic/electrophilic carboxylic acid group and a reactive terminal alkene — makes it an especially useful bifunctional building block in synthetic chemistry.

Key physical parameters reported in standard chemical references include a molecular weight of 86.09 g/mol and the molecular formula C₄H₆O₂. Researchers should consult the product specification sheet supplied with Aladdin SKU B152769 for lot-specific purity data, boiling point, and refractive index values.

Reactivity and Synthetic Utility

The bifunctional nature of 3-butenoic acid enables its participation in a wide range of chemical transformations, making it a valuable intermediate in both academic and industrial synthesis workflows.

Carboxylic Acid Reactivity: The –COOH group undergoes standard carboxylate chemistry including esterification, amide bond formation, anhydride synthesis, and conversion to acyl halides. These derivatives serve as activated intermediates for further elaboration.

Terminal Alkene Reactivity: The vinyl group participates in hydrogenation, halogenation, hydration, epoxidation, and radical or transition-metal-catalyzed reactions such as hydroformylation and metathesis. The Wacker oxidation of the terminal alkene can provide succinic acid derivatives. Ring-closing metathesis strategies employing 3-butenoic acid esters have been reported in the synthesis of lactone natural product analogs.

Cycloaddition Chemistry: As a dienophile, 3-butenoic acid and its ester derivatives participate in Diels-Alder reactions, providing cyclohexene carboxylic acid scaffolds relevant to medicinal chemistry.

Polymerization: The compound serves as a monomer or co-monomer in free-radical and controlled polymerization processes to produce carboxylic-acid-functionalized polymers with tunable properties.

Applications in Research and Industry

3-Butenoic acid finds application across several research domains owing to its dual functionality and straightforward derivatization:

• Natural Product Synthesis: Used as a building block for γ-lactones, β-lactams, and other ring systems common in bioactive natural products.
• Medicinal Chemistry: Serves as a precursor or linker in the preparation of drug candidates and prodrug systems where a reactive handle on both a carboxylate and an alkene is desirable.
• Polymer and Materials Science: Acts as a functional monomer yielding carboxylic-acid-pendant polymers for coatings, hydrogels, and adhesive formulations.
• Biochemistry and Metabolomics: Studied as a structural analog of short-chain fatty acids and as a reference standard in metabolic profiling experiments.
• Click and Bioorthogonal Chemistry: The terminal alkene moiety is compatible with thiol-ene and certain photochemical ligation strategies used in bioconjugation research.

Researchers selecting this reagent should verify purity and water content prior to use in moisture-sensitive reactions. Aladdin Scientific supplies 3-Butenoic Acid under SKU B152769; consult the product page for available pack sizes and current specifications.

Handling, Storage, and Safety Considerations

As with all reactive organic acids, appropriate precautions must be taken when handling 3-butenoic acid in the laboratory. The compound is corrosive to skin, eyes, and mucous membranes due to its acidic nature, and the volatile terminal alkene functionality may contribute to flammability.

Personal Protective Equipment (PPE): Chemical-resistant gloves (nitrile or neoprene), safety goggles, and a laboratory coat are recommended. Work should be conducted in a well-ventilated fume hood.

Storage: Store in a tightly sealed container under cool, dry, and dark conditions away from oxidizing agents and bases. Refrigerated storage (2–8 °C) is typically recommended to minimize polymerization or decomposition of the unsaturated acid over time.

Waste Disposal: Dispose of in accordance with local, regional, and national regulations governing organic acid waste. Do not pour down the drain without neutralization and regulatory approval.

SDS: Always consult the Safety Data Sheet (SDS) provided with Aladdin SKU B152769 before use. The SDS contains authoritative first-aid measures, fire-fighting information, and exposure limits specific to this product lot.

Frequently asked questions

What is the difference between 3-Butenoic Acid and crotonic acid?

Both are C4 unsaturated carboxylic acids, but they differ in double bond position. 3-Butenoic acid (but-3-enoic acid) has a terminal, non-conjugated alkene at C3–C4, whereas crotonic acid (but-2-enoic acid) has a conjugated double bond at C2–C3 directly adjacent to the carboxyl group. This difference profoundly affects their reactivity: crotonic acid is a classic Michael acceptor, while 3-butenoic acid behaves more like a simple terminal alkene in addition reactions.

How should 3-Butenoic Acid be stored to prevent degradation?

3-Butenoic acid should be stored in a tightly sealed container under cool (preferably 2–8 °C), dry, and dark conditions, away from oxidizing agents, strong bases, and sources of heat or ignition. Cold storage helps to prevent undesired radical or thermal polymerization of the vinyl group over extended periods. Always consult the SDS provided with SKU B152769 for lot-specific storage guidance.

Can 3-Butenoic Acid be used as a monomer in polymer synthesis?

Yes. The terminal vinyl group of 3-butenoic acid can participate in free-radical polymerization, yielding poly(3-butenoic acid) or carboxylic-acid-functionalized copolymers when combined with other vinyl monomers. Such polymers are of interest in hydrogel, coating, and adhesive applications. Reaction conditions, initiator choice, and inhibitor removal should be carefully optimized for each specific polymerization system.

Is 3-Butenoic Acid compatible with thiol-ene click chemistry?

Yes, the electron-neutral terminal alkene of 3-butenoic acid is well-suited for thiol-ene photochemical coupling, a type of click chemistry widely used in bioconjugation, surface functionalization, and hydrogel cross-linking. The carboxylic acid group can remain free for further conjugation or be protected prior to the thiol-ene step depending on the synthetic strategy.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 4th ed.; Wiley-Interscience: New York, 1992.
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012.
3. Hoyle, C. E.; Bowman, C. N. Thiol-Ene Click Chemistry. Angew. Chem. Int. Ed. 2010, 49, 1540–1573. doi:10.1002/anie.200903924
4. Aladdin Scientific. 3-Butenoic Acid, SKU B152769, Product Specification Sheet. Aladdin Scientific: Shanghai.

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