5-Ethynylthiophene-2-carbaldehyde: Properties & Lab Use FAQ
5-Ethynylthiophene-2-carbaldehyde: Properties & Lab Use FAQ
5-Ethynylthiophene-2-carbaldehyde is a bifunctional heterocyclic building block bearing both a terminal alkyne and an aldehyde group on a thiophene scaffold, making it a versatile intermediate for organic synthesis and materials chemistry.
- Product Name
- 5-Ethynylthiophene-2-carbaldehyde
- SKU
- E728394
- Molecular Formula
- C7H4OS
- Key Functional Groups
- Terminal alkyne (–C≡CH) and aldehyde (–CHO) on a thiophene ring
- Primary Applications
- Copper-catalyzed azide-alkyne cycloaddition (CuAAC), Sonogashira coupling, Knoevenagel condensation, and fluorescent probe synthesis
- Recommended Storage
- Cool, dry, dark conditions; inert atmosphere recommended to protect aldehyde and alkyne moieties
What Is 5-Ethynylthiophene-2-carbaldehyde?
5-Ethynylthiophene-2-carbaldehyde (SKU E728394) is an aromatic heterocyclic compound featuring a thiophene ring substituted at the 2-position with a formyl (aldehyde) group and at the 5-position with a terminal ethynyl (alkyne) group. This dual-functionality makes it particularly valuable in synthetic chemistry, where the two reactive handles can be addressed independently or in tandem under orthogonal reaction conditions.
The thiophene core contributes to the compound's π-conjugation, electron-withdrawing character of the ring, and compatibility with cross-coupling reactions. The compound is a solid or low-melting material and should be handled in a well-ventilated fume hood with appropriate personal protective equipment.
Key Reactions and Synthetic Applications
Terminal Alkyne Reactivity: The terminal alkyne at the 5-position is ideally suited for copper-catalyzed azide-alkyne cycloaddition (CuAAC, a classic click chemistry reaction), Sonogashira cross-coupling with aryl or vinyl halides, and Glaser homocoupling. These reactions allow rapid construction of complex conjugated or triazole-containing architectures.
Aldehyde Reactivity: The aldehyde group at the 2-position participates in Knoevenagel condensations, reductive amination, imine (Schiff base) formation, Wittig and Horner–Wadsworth–Emmons olefination, and nucleophilic additions. This versatility makes the compound a useful handle for attaching diverse functional groups.
Combined Utility: By exploiting both functional groups, researchers can use 5-Ethynylthiophene-2-carbaldehyde as a bifunctional linker in the synthesis of fluorescent dyes, organic semiconductors, and covalent organic frameworks (COFs).
Handling, Storage, and Stability
Storage: Store the compound in a tightly sealed container under an inert atmosphere (nitrogen or argon) in a cool, dark, and dry environment. Both the aldehyde and terminal alkyne functional groups can be susceptible to oxidation and moisture over time, so minimizing exposure to air and humidity is recommended.
Handling Precautions: As with most fine chemical aldehydes and alkynes, standard laboratory precautions apply: wear nitrile gloves, safety goggles, and a laboratory coat. Work in a fume hood to avoid inhalation of dust or vapors. Consult the Safety Data Sheet (SDS) supplied with the product before use.
Stability Notes: Prolonged exposure to light, heat, or moisture may cause gradual decomposition or polymerization of the terminal alkyne. It is good practice to inspect the compound visually and, if in doubt, confirm identity and purity by NMR or HPLC before use in sensitive applications.
Frequently Asked Questions: Ordering and Specifications
What purity grade is available? Please refer to the current product listing for E728394 on the Aladdin Scientific website for the latest purity specification and available pack sizes, as these details may be updated periodically.
Can I request a Certificate of Analysis (CoA)? Yes. A CoA is available for each lot of E728394. Contact Aladdin Scientific customer service with your lot number to obtain a copy, or download it directly from the product page.
Is bulk or custom quantity available? For bulk orders or custom synthesis inquiries, please contact Aladdin Scientific's sales team directly. Custom quantities and packaging may be arranged depending on demand and lead time.
Frequently asked questions
What makes 5-Ethynylthiophene-2-carbaldehyde useful as a building block in organic synthesis?
The compound carries two orthogonally reactive functional groups—a terminal alkyne and an aldehyde—on a π-conjugated thiophene scaffold. This allows chemists to perform sequential or selective reactions such as CuAAC click chemistry on the alkyne while reserving the aldehyde for condensation or olefination steps, enabling rapid assembly of complex molecular architectures.
How should I store 5-Ethynylthiophene-2-carbaldehyde to maintain its integrity?
Store E728394 in a tightly sealed vial under an inert gas (nitrogen or argon) in a cool, dry, and dark location. Avoid prolonged exposure to air, moisture, and light, as these conditions can degrade both the aldehyde and the terminal alkyne over time. Confirm purity by NMR or HPLC if the material has been stored for an extended period before use in critical experiments.
Can 5-Ethynylthiophene-2-carbaldehyde be used in Sonogashira coupling reactions?
Yes, the terminal alkyne of 5-Ethynylthiophene-2-carbaldehyde is well-suited for palladium/copper-catalyzed Sonogashira coupling with aryl, heteroaryl, or vinyl halides, enabling the introduction of extended π-conjugated systems. Standard Sonogashira conditions (Pd catalyst, CuI co-catalyst, amine base, inert atmosphere) should be applied. The aldehyde group is generally compatible with these mild conditions but should be considered when choosing solvents and bases.
Is a Certificate of Analysis available for E728394?
Yes, a Certificate of Analysis (CoA) is available for each production lot of E728394. You can request it from Aladdin Scientific customer service by providing your lot number, or download it directly from the product page on the Aladdin Scientific website.
What safety precautions should I take when handling 5-Ethynylthiophene-2-carbaldehyde?
Always consult the Safety Data Sheet (SDS) before handling E728394. Use appropriate personal protective equipment including nitrile gloves, safety goggles, and a laboratory coat. Handle the compound in a chemical fume hood to minimize inhalation risk. Avoid contact with skin, eyes, and clothing, and wash thoroughly after handling.
References
- Rostovtsev, V. V.; Green, L. G.; Fokin, V. V.; Sharpless, K. B. A stepwise Huisgen cycloaddition process: copper(I)-catalyzed regioselective ligation of azides and terminal alkynes. Angew. Chem. Int. Ed. 2002, 41, 2596–2599. doi:10.1002/anie.200200161
- Sonogashira, K.; Tohda, Y.; Hagihara, N. A convenient synthesis of acetylenes: catalytic substitutions of acetylenic hydrogen with bromoalkenes, iodoarenes and bromopyridines. Tetrahedron Lett. 1975, 16, 4467–4470. doi:10.1016/S0040-4039(00)91094-3
- Aladdin Scientific. Product page: 5-Ethynylthiophene-2-carbaldehyde, SKU E728394. Aladdin Scientific official website.
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