Methyl 4-Bromo-3-Hydroxythiophene-2-Carboxylate: Handling Protocol

methyl 4-bromo-3-hydroxythiophene-2-carboxylate is a versatile brominated hydroxythiophene building block widely employed in heterocyclic synthesis, medicinal chemistry, and materials science research.

Product Name

Methyl 4-bromo-3-hydroxythiophene-2-carboxylate

SKU

M635311

Molecular Formula

C6H5BrO3S

Molecular Weight

237.07 g/mol

Key Functional Groups

Bromine (C-4), hydroxyl (C-3), methyl ester (C-2) on thiophene ring

Recommended Storage

Cool, dry, well-ventilated location; protect from moisture and light

Scope and Safety Considerations

This protocol covers safe receipt, storage, weighing, dissolution, and disposal of methyl 4-bromo-3-hydroxythiophene-2-carboxylate (Aladdin SKU M635311), a brominated thiophene ester used as an intermediate in heterocyclic and medicinal chemistry.

Personal Protective Equipment (PPE): Wear nitrile gloves, a laboratory coat, and safety goggles at all times when handling this compound. Work in a well-ventilated fume hood to avoid inhalation of dust or vapors.

Hazard overview: As a halogenated organic ester, this compound should be treated as a potential irritant to skin, eyes, and the respiratory tract. Consult the Safety Data Sheet (SDS) supplied with the product before use. In case of skin or eye contact, rinse immediately with copious water and seek medical advice.

Waste disposal: Collect all waste solutions and contaminated materials in clearly labelled halogenated organic waste containers and dispose of according to local institutional and governmental regulations for halogenated organic solvents.

Storage and Stability

Store methyl 4-bromo-3-hydroxythiophene-2-carboxylate in a tightly sealed container in a cool (recommended 2–8 °C or room temperature as specified on the product label), dry, and well-ventilated area away from heat sources, direct sunlight, strong oxidisers, and strong bases.

The free hydroxyl group on the thiophene ring can undergo esterification, etherification, or tautomeric equilibria under harsh conditions; therefore, avoid prolonged exposure to strong acids, bases, or high temperatures. The methyl ester moiety is susceptible to hydrolysis under strongly alkaline or strongly acidic aqueous conditions.

Upon receipt, inspect the container for integrity. If the compound appears discoloured or has formed significant solid agglomerates, consult Aladdin Scientific technical support before use. Under recommended storage conditions, the compound is expected to be stable for the duration of the stated shelf life on the certificate of analysis.

Weighing and Solution Preparation

Equilibration: Allow the sealed container to equilibrate to room temperature before opening to prevent moisture condensation on the solid, which could lead to hydrolysis of the ester group or physical clumping.

Weighing: Tare an appropriate glass or polypropylene vessel on an analytical balance. Transfer the required amount of methyl 4-bromo-3-hydroxythiophene-2-carboxylate using a clean, dry spatula. Replace the container cap promptly after use and reseal under inert atmosphere (e.g., dry nitrogen or argon back-fill) if long-term storage is intended after partial use.

Solubility and solvent selection: This compound is expected to dissolve in common polar aprotic organic solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), dichloromethane (DCM), ethyl acetate, and tetrahydrofuran (THF). Solubility in water is anticipated to be low due to the lipophilic thiophene ring and ester group. Select the solvent compatible with the downstream synthetic or analytical application.

Stock solution preparation: Prepare stock solutions in dry solvent under inert gas where moisture-sensitive downstream reactions are planned. Filter through a 0.22 µm PTFE syringe filter if particle-free solutions are required for analytical work. Verify concentration by analytical methods appropriate to the application (e.g., gravimetric, UV-Vis, or NMR).

Typical Synthetic Applications

Methyl 4-bromo-3-hydroxythiophene-2-carboxylate is a multifunctional building block offering three orthogonal handles for chemical elaboration:

• C–C coupling via the C-4 bromine: The aryl C–Br bond is well-suited for palladium-catalysed cross-coupling reactions, including Suzuki-Miyaura, Negishi, Stille, and Sonogashira couplings, enabling introduction of aryl, alkenyl, alkynyl, or alkyl substituents at the 4-position of the thiophene ring.
• O-functionalisation via the C-3 hydroxyl: The phenolic-type hydroxyl group can be alkylated (O-alkylation using alkyl halides and base), acylated, sulfonylated, or converted to a triflate for further cross-coupling, providing access to O-substituted thiophene scaffolds.
• Ester manipulation at C-2: The methyl ester can be hydrolysed to the corresponding carboxylic acid, reduced to the hydroxymethyl derivative, converted to an amide, or employed in Claisen-type condensations, extending the range of accessible thiophene-2-carboxylate derivatives.

These combined reactivities make this compound a valuable precursor for constructing fused heterocyclic systems, pharmaceutical intermediates, agrochemical scaffolds, and functional organic materials such as organic semiconductors and dyes.

Quality Verification and Troubleshooting

Identity confirmation: Confirm the identity of the compound by comparing the recorded melting point, ¹H NMR spectrum (characteristic signals: aromatic/vinyl H on thiophene, OH proton, and OCH₃ singlet), ¹³C NMR, and high-resolution mass spectrometry data against literature or the Aladdin certificate of analysis (CoA).

Purity assessment: Analyse purity by HPLC (reverse-phase C18 column, UV detection at 254 nm or 280 nm) or by quantitative NMR. The CoA provided with SKU M635311 specifies the guaranteed purity level; contact Aladdin Scientific if results fall outside specification.

Common issues and remedies:

• Poor solubility: Gently warm the solution (40–50 °C) with stirring; avoid prolonged heating that may cause decomposition. Switch to a more polar aprotic solvent if necessary.
• Unexpected colour change: Discolouration may indicate oxidation or moisture ingress. Discard the affected batch and request a replacement if within warranty period.
• Low yield in cross-coupling: Ensure rigorous exclusion of oxygen and moisture; verify catalyst loading, ligand, base, and solvent compatibility with the specific coupling protocol employed.
• Ester hydrolysis side product observed: Minimise exposure to protic solvents and aqueous media containing base or acid during purification steps.

Frequently asked questions

What solvents are recommended for dissolving methyl 4-bromo-3-hydroxythiophene-2-carboxylate?

Polar aprotic solvents such as DMSO, DMF, DCM, THF, and ethyl acetate are recommended. Aqueous solubility is expected to be low due to the lipophilic thiophene ester scaffold. Avoid prolonged contact with strongly alkaline or acidic aqueous media to prevent ester hydrolysis.

Can the C-4 bromine be used directly in palladium-catalysed cross-coupling reactions?

Yes. The aryl C–Br bond at the 4-position of the thiophene ring is reactive in palladium-catalysed cross-coupling reactions including Suzuki-Miyaura, Negishi, Stille, and Sonogashira protocols. Standard conditions for aryl bromides are generally applicable; optimisation of catalyst, ligand, and base may be required for specific substrates.

How should I store methyl 4-bromo-3-hydroxythiophene-2-carboxylate after partial use?

After partial use, reseal the container tightly under an inert atmosphere (dry nitrogen or argon) to exclude moisture and oxygen. Store in a cool, dry location away from light and incompatible materials. Allow the container to return to room temperature before reopening to minimise condensation.

What is the molecular weight of methyl 4-bromo-3-hydroxythiophene-2-carboxylate?

The molecular weight of methyl 4-bromo-3-hydroxythiophene-2-carboxylate (molecular formula C6H5BrO3S) is approximately 237.07 g/mol. Please verify against the certificate of analysis supplied with SKU M635311 for the exact value confirmed by the analytical batch.

Is the hydroxyl group at the 3-position available for O-alkylation or other derivatisation?

Yes. The hydroxyl group at the 3-position of the thiophene ring can be selectively derivatised by O-alkylation with alkyl halides in the presence of a suitable base, acylation with acyl chlorides or anhydrides, sulfonylation, or conversion to a triflate for subsequent cross-coupling. Careful control of reaction conditions is required to avoid competing N- or C-alkylation and ester side reactions.

References

1. Aladdin Scientific. Product Certificate of Analysis, methyl 4-bromo-3-hydroxythiophene-2-carboxylate, SKU M635311. Aladdin Scientific Corp.
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. Chapter on heterocyclic chemistry and cross-coupling reactions.
3. Joule, J. A.; Mills, K. Heterocyclic Chemistry, 5th ed.; Wiley-Blackwell: Oxford, 2010. Chapter on thiophene chemistry.

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