2-Methylbenzo[b]thiophene-3-carbaldehyde: Lab Handling Guide

2-Methylbenzo[b]thiophene-3-carbaldehyde is a heteroaromatic aldehyde building block widely employed in organic synthesis for the construction of biologically active scaffolds and functional materials.

Chemical Name

2-Methylbenzo[b]thiophene-3-carbaldehyde

SKU

M708884

Functional Group

Aldehyde (–CHO) on a benzo[b]thiophene ring system

Molecular Framework

Bicyclic benzo[b]thiophene with methyl substituent at position 2 and formyl group at position 3

Typical Applications

Condensation reactions, Knoevenagel reactions, Wittig olefination, and heterocyclic synthesis

Storage Recommendation

Store in a cool, dry, well-ventilated area away from oxidizers and ignition sources

Chemical Identity and Properties

2-Methylbenzo[b]thiophene-3-carbaldehyde is a bicyclic heteroaromatic compound belonging to the benzo[b]thiophene family. The molecule features a sulfur-containing fused bicyclic ring system with a methyl group at the 2-position and an aldehyde (–CHO) functionality at the 3-position. This combination makes it an electron-rich yet reactive aromatic aldehyde.

The presence of the sulfur atom in the thiophene ring confers unique electronic properties, including enhanced polarizability and the ability to participate in non-covalent interactions such as S···π and S···H contacts. These characteristics distinguish it from purely carbocyclic aromatic aldehydes and broaden its utility in medicinal chemistry and materials science.

Researchers should be aware that, like most aromatic aldehydes, this compound can undergo oxidation to the corresponding carboxylic acid upon prolonged exposure to air and light. Purity should be verified by NMR or HPLC prior to use in quantitative or structure-sensitive reactions.

Synthesis and Key Reactions

2-Methylbenzo[b]thiophene-3-carbaldehyde serves as a versatile electrophilic partner in a range of synthetic transformations. The aldehyde group is the primary site of reactivity and enables the following key reaction classes:

• Knoevenagel Condensation: Reaction with active methylene compounds (e.g., malononitrile, ethyl cyanoacetate) in the presence of a base catalyst yields arylidene derivatives useful as dyes, sensors, and pharmaceutical intermediates.
• Wittig and Horner–Wadsworth–Emmons Olefination: The aldehyde reacts efficiently with phosphorus ylides or stabilized phosphonate carbanions to give conjugated alkenes, extending the π-system of the benzo[b]thiophene core.
• Reductive Amination: Condensation with primary or secondary amines followed by reduction affords benzothiophenylmethyl amines, which are valuable pharmacophores.
• Schiff Base Formation: Reaction with aromatic or aliphatic amines yields imines (Schiff bases) that are widely studied as ligands in coordination chemistry and as bioactive molecules.
• Nucleophilic Addition: Grignard or organolithium reagents add to the carbonyl to give secondary alcohols, which may be further elaborated.

The methyl group at position 2 can also participate in reactions under strongly basic conditions, including aldol-type condensations, offering an additional handle for molecular diversification.

Handling, Safety, and Storage Guidelines

Although 2-Methylbenzo[b]thiophene-3-carbaldehyde is not classified as a highly hazardous material under standard research conditions, good laboratory practice requires adherence to the following precautions:

• Personal Protective Equipment (PPE): Wear chemical-resistant gloves (nitrile recommended), a lab coat, and safety glasses at all times when handling. Use a fume hood to avoid inhalation of vapors or dust.
• Storage: Store in a tightly sealed container in a cool (15–25 °C), dry, and well-ventilated location. Keep away from strong oxidizing agents, strong acids, and ignition sources. Protect from prolonged exposure to light to prevent aldehyde oxidation.
• Stability: The compound is expected to be stable under recommended storage conditions. However, prolonged storage may lead to partial oxidation or discoloration; verify purity before critical experiments.
• Spill Management: Absorb spills with an inert material (e.g., vermiculite or dry sand), collect into a sealed container, and dispose of in accordance with local chemical waste regulations.
• First Aid: In case of skin contact, wash thoroughly with soap and water. For eye contact, rinse with copious water for at least 15 minutes and seek medical attention. If inhaled, move to fresh air.

Always consult the current Safety Data Sheet (SDS) for this product before use, as specific hazard classifications may be updated.

Applications in Medicinal and Materials Chemistry

The benzo[b]thiophene scaffold is a privileged structure in drug discovery. Several approved pharmaceuticals—including raloxifene (osteoporosis) and zileuton (asthma)—incorporate the benzothiophene core, underscoring the biological relevance of this ring system. 2-Methylbenzo[b]thiophene-3-carbaldehyde provides a functionalized entry point to this pharmacophore space.

In medicinal chemistry, derivatives obtained from this aldehyde have been investigated as:

• Antimicrobial and antifungal agents via Schiff base or hydrazone formation
• Anticancer scaffolds through Knoevenagel-derived arylidene compounds
• Enzyme inhibitor precursors exploiting the sulfur atom for binding interactions

In materials science, the extended conjugation accessible through olefination and condensation reactions makes benzothiophene-3-carbaldehyde derivatives attractive for:

• Organic dyes and sensitizers in dye-sensitized solar cells (DSSCs)
• Fluorescent probes and chemosensors
• Organic semiconductors and optoelectronic materials

Researchers are encouraged to conduct a thorough literature search before initiating a new synthetic program to identify the most relevant precedents and optimize reaction conditions for their specific target.

Quality, Ordering, and Technical Support

Aladdin Scientific offers 2-Methylbenzo[b]thiophene-3-carbaldehyde under SKU M708884. Researchers should confirm the required purity grade, quantity, and packaging format at the time of order to ensure suitability for their application.

Quality Assurance: Customers are advised to request a Certificate of Analysis (CoA) for each lot, which typically includes identity confirmation (NMR or IR), purity (GC or HPLC), and physical appearance data. If the compound will be used in biological assays, additional tests such as residual solvent analysis may be warranted.

Ordering: Place orders directly through the Aladdin Scientific website or contact your regional sales representative. Bulk quantities and custom packaging may be available upon request. For institutional procurement, Aladdin Scientific supports standard purchase order workflows.

Technical Support: For questions regarding compound compatibility, reaction conditions, or alternative reagents, contact Aladdin Scientific technical support. Our scientific team can assist with reagent selection and provide application notes where available.

Returns and Compliance: Products must be inspected upon receipt. Any quality discrepancies should be reported within the time frame specified in Aladdin Scientific's returns and refunds policy. All shipments comply with applicable regulations for chemical transport.

Frequently asked questions

What is 2-Methylbenzo[b]thiophene-3-carbaldehyde used for in organic synthesis?

It is primarily used as an electrophilic building block in reactions such as Knoevenagel condensation, Wittig olefination, reductive amination, and Schiff base formation. These transformations yield heterocyclic intermediates relevant to drug discovery, fluorescent dye development, and materials science.

How should I store 2-Methylbenzo[b]thiophene-3-carbaldehyde to maintain its purity?

Store the compound in a tightly sealed container at 15–25 °C in a cool, dry, and well-ventilated area, away from light, strong oxidizers, and ignition sources. Prolonged exposure to air and light may cause gradual oxidation of the aldehyde to the corresponding carboxylic acid, so verify purity by GC, HPLC, or NMR before critical experiments.

What safety precautions should I take when handling this compound?

Always handle in a fume hood wearing nitrile gloves, a lab coat, and safety glasses. In case of skin or eye contact, flush with water immediately; for eye exposure, rinse for at least 15 minutes and seek medical attention. Consult the current Safety Data Sheet (SDS) for full hazard and first-aid information before use.

What is the Aladdin Scientific SKU for 2-Methylbenzo[b]thiophene-3-carbaldehyde?

The SKU for 2-Methylbenzo[b]thiophene-3-carbaldehyde at Aladdin Scientific is M708884. Contact Aladdin Scientific sales or visit the website to check current stock, available quantities, and pricing.

Can the methyl group at position 2 be used as a synthetic handle?

Yes, under strongly basic conditions the methyl group at position 2 can be deprotonated to form a stabilized benzylic anion, enabling aldol-type condensations and other C–C bond-forming reactions. This provides an additional site for molecular diversification beyond the aldehyde functionality.

References

1. Fringuelli, F.; Taticchi, A. The Diels-Alder Reaction: Selected Practical Methods. Wiley, 2002. (General heterocyclic aldehyde chemistry context)
2. Joule, J. A.; Mills, K. Heterocyclic Chemistry, 5th ed. Wiley-Blackwell, 2010. (Benzo[b]thiophene ring system chemistry)
3. Aladdin Scientific Product Page, SKU M708884: 2-Methylbenzo[b]thiophene-3-carbaldehyde. (Accessed via internal source material)

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