4-(5-Formyl-2-thienyl)benzoic Acid: Properties & Lab Guide

4-(5-Formyl-2-thienyl)benzoic acid is a bifunctional heterocyclic compound bearing both an aldehyde and a carboxylic acid group, making it a versatile building block for organic synthesis, coordination chemistry, and functional materials development.

Chemical Name

4-(5-Formyl-2-thienyl)benzoic acid

SKU

F167923

Functional Groups

Aldehyde (–CHO) and carboxylic acid (–COOH) on a thienyl–phenyl scaffold

Core Structure

2,5-disubstituted thiophene linked to a para-substituted benzoic acid

Recommended Storage

Store in a cool, dry place away from light and moisture; seal tightly after use

Primary Applications

MOF synthesis, Schiff base formation, cross-coupling reactions, optoelectronic materials

Chemical Identity and Structural Features

4-(5-Formyl-2-thienyl)benzoic acid is a heteroaromatic compound in which a thiophene ring serves as a conjugated linker between an aldehyde functional group at the 5-position and a benzoic acid moiety at the 2-position. This arrangement creates an extended π-conjugated system that promotes efficient electronic communication between the two terminal functional groups.

The presence of two orthogonal reactive handles — the electrophilic aldehyde and the acidic carboxylate — on a single, planar aromatic scaffold is the defining structural attribute of this compound. The thiophene ring contributes favorable optoelectronic properties relative to its all-carbocyclic analogues, including a lower aromatic stabilization energy that facilitates participation in conjugated polymer backbones and charge-transfer assemblies.

This compound is sometimes referred to by its systematic IUPAC name or described generically as a 2,5-thienylene-bridged bifunctional acid-aldehyde. Researchers should confirm identity via CAS number and spectroscopic data upon receipt.

Key Applications in Research

Metal–Organic Framework (MOF) Construction: The carboxylic acid group enables coordination to metal nodes under solvothermal or ambient conditions, while the free aldehyde can be exploited for post-synthetic modification (PSM). This dual reactivity makes 4-(5-Formyl-2-thienyl)benzoic acid an attractive linker candidate for constructing porous frameworks with built-in functional handles.

Schiff Base and Imine Chemistry: Condensation of the aldehyde group with primary amines yields Schiff bases (imines), which are widely employed in ligand design for coordination complexes, sensing platforms, and catalytic systems. The rigidity and planarity of the thienyl–phenyl backbone help preorganize the resulting ligand for selective metal binding.

Cross-Coupling and Heterocyclic Synthesis: The compound can serve as a versatile intermediate in palladium-catalyzed cross-coupling reactions (e.g., Suzuki–Miyaura) when appropriately functionalized, or as a building block for the synthesis of more complex π-conjugated heterocycles.

Optoelectronic and Dye-Sensitized Applications: The extended conjugation and dual-donor/acceptor functionality make this compound relevant to the design of organic dyes, push–pull chromophores, and sensitizers for dye-sensitized solar cells (DSSCs), where both anchoring (–COOH) and light-harvesting capabilities are required.

Handling, Storage, and Safety Guidelines

Personal Protective Equipment (PPE): Handle 4-(5-Formyl-2-thienyl)benzoic acid using standard laboratory PPE including nitrile gloves, safety glasses, and a laboratory coat. Work in a well-ventilated area or fume hood, particularly when weighing powders, to avoid inhalation of fine particulates.

Storage Conditions: Store the compound in a tightly sealed container in a cool (typically 2–8 °C or room temperature as specified on the product label), dry location away from direct light, moisture, and incompatible materials such as strong oxidizers and strong bases. Prolonged exposure to moisture may lead to hydration or partial decomposition of the aldehyde functionality.

Stability Considerations: The aldehyde group is susceptible to oxidation to the corresponding carboxylic acid upon prolonged air exposure. It is advisable to work under an inert atmosphere (nitrogen or argon) when high purity is critical. Solutions in organic solvents should be prepared fresh or stored under inert gas at reduced temperature.

Waste Disposal: Dispose of waste containing this compound in accordance with local, institutional, and national regulations for organic chemical waste. Do not dispose of down the drain without appropriate treatment.

Analytical Characterization and Purity Verification

Upon receipt, researchers should verify the identity and purity of 4-(5-Formyl-2-thienyl)benzoic acid using standard analytical techniques before use in sensitive applications.

1H NMR Spectroscopy: The aldehyde proton typically resonates as a singlet in the range of δ 9.9–10.1 ppm. Aromatic protons of the thiophene ring appear in the δ 7.5–7.9 ppm region, while the benzoic acid aromatic protons appear as an AA'BB' system around δ 7.8–8.1 ppm. The carboxylic acid proton is broad and may not always be observed depending on solvent.

HPLC and Melting Point: High-performance liquid chromatography provides a quantitative measure of chemical purity. Melting point determination offers a rapid orthogonal check; researchers should compare observed values against the certificate of analysis (CoA) provided with each lot.

IR Spectroscopy: Key IR absorptions expected include a strong C=O stretch for the aldehyde (~1675–1700 cm⁻¹), a broad O–H stretch for the carboxylic acid (~2500–3300 cm⁻¹), and C=O stretch for the carboxylate (~1680–1710 cm⁻¹).

Mass Spectrometry: The molecular ion peak and fragmentation pattern should be consistent with the molecular formula. Researchers are encouraged to consult the Aladdin Scientific product page or CoA for lot-specific analytical data.

Ordering, Specifications, and Quality Assurance

4-(5-Formyl-2-thienyl)benzoic acid is available from Aladdin Scientific under SKU F167923. Researchers and procurement teams should reference this SKU when placing orders to ensure the correct compound and grade are supplied.

Specifications: Each lot is manufactured and tested to defined purity specifications. A Certificate of Analysis (CoA) is available for each lot and should be requested or downloaded from the Aladdin Scientific website at the time of purchase. The CoA typically includes purity (by HPLC or alternative method), appearance, and NMR confirmation.

Available Pack Sizes: Aladdin Scientific offers this compound in multiple pack sizes to accommodate both exploratory research and larger-scale synthetic campaigns. Contact Aladdin customer service or visit the product page for current availability and pricing.

Quality Assurance: Aladdin Scientific applies rigorous quality control processes, and each batch is traceable. Customers experiencing quality concerns are encouraged to contact the technical support team and reference the lot number printed on the product label. Returns and replacements are handled in accordance with Aladdin Scientific's standard returns and refund policy.

Frequently asked questions

What are the main reactive functional groups in 4-(5-Formyl-2-thienyl)benzoic acid and how can they be exploited synthetically?

The compound carries two independent reactive groups: an aldehyde (–CHO) and a carboxylic acid (–COOH). The aldehyde undergoes condensation with primary amines to form imines (Schiff bases), reductive amination, or Knoevenagel condensation, while the carboxylic acid can form amide bonds, esters, or coordinate to metal ions — enabling sequential or orthogonal functionalization strategies.

How should I store 4-(5-Formyl-2-thienyl)benzoic acid to maintain its stability and purity?

Store the compound in a tightly sealed container in a cool, dry, dark location, following the conditions stated on the product label and Certificate of Analysis. Protect from moisture and strong oxidizing agents, as prolonged air exposure can lead to oxidation of the aldehyde group. For long-term storage, consider use of an inert atmosphere and refrigerated conditions.

Is 4-(5-Formyl-2-thienyl)benzoic acid suitable for use as a linker in metal–organic framework synthesis?

Yes, the carboxylic acid group allows coordination to metal clusters or nodes under typical MOF synthesis conditions (solvothermal or room-temperature methods), while the pendant aldehyde group provides a handle for post-synthetic modification. This bifunctionality makes it an attractive candidate for the construction of functional MOFs with tunable interior chemistry.

How do I confirm the identity and purity of 4-(5-Formyl-2-thienyl)benzoic acid on receipt?

Cross-reference the lot-specific Certificate of Analysis (CoA) available from Aladdin Scientific. For independent verification, use 1H NMR (look for the aldehyde singlet near δ 9.9–10.1 ppm), HPLC for purity, IR spectroscopy for characteristic carbonyl stretches, and melting point determination. Contact Aladdin's technical support team if there are any discrepancies.

What solvents are suitable for dissolving 4-(5-Formyl-2-thienyl)benzoic acid?

Polar aprotic solvents such as DMSO and DMF are generally effective for dissolving bifunctional aromatic acid-aldehyde compounds of this type. Ethanol and THF may also be considered. Solubility in water is expected to be low due to the hydrophobic heterocyclic core; verify solubility empirically for your specific application and note that solubility data should be confirmed against the CoA or product specification sheet.

References

1. Aladdin Scientific Product Page: 4-(5-Formyl-2-thienyl)benzoic acid, SKU F167923. Aladdin Scientific.
2. Yaghi, O. M. et al. Reticular synthesis and the design of new materials. Nature 2003, 423, 705–714. doi:10.1038/nature01650
3. Brønsted, J. N. Acid–base reactions and condensation chemistry of aldehydes with amines (general textbook reference for Schiff base formation). General Organic Chemistry reference.
4. Hagfeldt, A. et al. Dye-sensitized solar cells. Chemical Reviews 2010, 110, 6595–6663. doi:10.1021/cr900356p

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