6-Bromo-o-cresol: Properties, Uses & Lab Guide

6-Bromo-o-cresol is a halogenated phenolic compound widely employed as a versatile intermediate in organic synthesis, medicinal chemistry, and materials science research.

IUPAC Name

2-bromo-6-methylphenol

CAS Number

6940-50-7

Molecular Formula

C₇H₇BrO

Molecular Weight

187.03 g/mol

Appearance

Colorless to pale yellow liquid or low-melting solid

Functional Groups

Phenol (–OH), aryl bromide (C–Br), methyl (–CH₃)

Aladdin SKU

B152683

Chemical Identity and Physical Properties

6-Bromo-o-cresol, systematically named 2-bromo-6-methylphenol, is a member of the halogenated cresol family. Its structure features an ortho-methyl group and a bromine substituent flanking the phenolic hydroxyl group, creating a sterically defined aromatic scaffold. The molecular formula is C₇H₇BrO with a molecular weight of approximately 187.03 g/mol (CAS 6940-50-7).

The compound typically presents as a colorless to pale yellow liquid or low-melting solid at room temperature. The phenolic –OH group confers moderate acidity (pKa estimated in the range of phenolic compounds, approximately 8–10), while the aryl bromide bond provides a handle for transition-metal-catalyzed cross-coupling reactions. The ortho-methyl and ortho-bromo substitution pattern creates steric interactions that influence both the reactivity of the phenol oxygen and the selectivity of further electrophilic or nucleophilic transformations.

The compound is sparingly soluble in water but dissolves readily in common organic solvents such as dichloromethane, ethyl acetate, tetrahydrofuran, and methanol, facilitating its use across a broad range of synthetic protocols.

Synthesis and Role as a Synthetic Intermediate

6-Bromo-o-cresol can be prepared by regioselective electrophilic aromatic bromination of o-cresol (2-methylphenol). The phenolic hydroxyl group strongly activates the aromatic ring toward electrophilic substitution and directs incoming electrophiles preferentially to the ortho and para positions. Because the 2-position (adjacent to –OH) is already occupied by the methyl group, bromination proceeds preferentially at the 6-position (the remaining ortho position relative to –OH), yielding the 6-bromo regioisomer as the principal product under controlled conditions.

As a synthetic building block, 6-Bromo-o-cresol is particularly valuable because it combines three distinct reactive sites in a single molecule: the phenolic hydroxyl for O-alkylation, O-acylation, or metal coordination; the aryl bromide for palladium-catalyzed Suzuki–Miyaura, Negishi, Buchwald–Hartwig, or Ullmann-type reactions; and the methyl group, which can be further functionalized via benzylic oxidation or halogenation. This multifunctionality makes it an attractive precursor for the construction of complex biaryl frameworks, benzofurans, and other heterocyclic scaffolds encountered in pharmaceutical and agrochemical research.

Research Applications

Medicinal Chemistry: Halogenated phenols and their derivatives appear frequently in drug discovery programs. The aryl bromide moiety of 6-Bromo-o-cresol enables rapid diversification via cross-coupling chemistry, supporting the construction of focused compound libraries for target-based screening. The phenolic scaffold is also found in natural product analogs and bioactive molecules targeting enzymes and receptors.

Materials Science: Brominated phenols serve as monomers or chain-end functionalization agents in the synthesis of polyphenylene ethers, conjugated polymers, and dendrimeric architectures. The defined substitution pattern of 6-Bromo-o-cresol can be exploited to introduce specific steric and electronic properties into polymer backbones.

Agrochemical Intermediates: Halogenated cresols are recognized intermediates in the synthesis of herbicides, fungicides, and insecticides. The combined lipophilicity contributed by the bromo and methyl substituents can modulate membrane permeability in agrochemical candidates.

Analytical and Reference Standards: High-purity 6-Bromo-o-cresol from a reliable supplier such as Aladdin Scientific can serve as a reference standard for method development in environmental monitoring of halogenated phenolic pollutants.

Handling, Storage, and Safety Considerations

As with most halogenated phenols, 6-Bromo-o-cresol should be handled with appropriate laboratory precautions. Phenolic compounds are skin and eye irritants and may cause systemic toxicity upon prolonged exposure. Researchers should consult the Safety Data Sheet (SDS) provided with the product prior to use.

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

Storage: Store in a tightly sealed container, away from light, moisture, and incompatible materials such as strong oxidizers and bases. A cool, dry environment (2–8 °C or as specified on the product label) is recommended to maintain stability and prevent discoloration.

Waste Disposal: Dispose of waste material in accordance with applicable local, regional, and national environmental regulations. Do not pour halogenated organics into general drain systems.

First Aid: In case of skin or eye contact, flush immediately with copious amounts of water and seek medical attention if irritation persists. Refer to the SDS for comprehensive emergency procedures.

Ordering Information and Quality Specifications

Aladdin Scientific supplies 6-Bromo-o-cresol (SKU: B152683) as a research-grade reagent. For precise purity specifications, available pack sizes, current pricing, and certificate of analysis (CoA), please refer to the product detail page on the Aladdin Scientific website or contact our technical sales team.

When evaluating reagent quality for sensitive synthetic applications, key parameters to verify include: assay purity (typically reported by GC or HPLC), water content (Karl Fischer), and the absence of regioisomeric impurities (2-bromo-4-methylphenol or 4-bromo-2-methylphenol), which can arise from less selective bromination procedures. Aladdin Scientific provides certificates of analysis on request to support your quality-assurance workflows.

Bulk quantities and custom packaging may be available for industrial or high-throughput screening applications. Contact Aladdin Scientific customer service for volume pricing and lead-time information.

Frequently asked questions

What is the CAS number and molecular formula of 6-Bromo-o-cresol?

6-Bromo-o-cresol has the CAS number 6940-50-7 and the molecular formula C₇H₇BrO, corresponding to a molecular weight of approximately 187.03 g/mol. It is also known by the IUPAC name 2-bromo-6-methylphenol.

What types of chemical reactions can 6-Bromo-o-cresol participate in?

6-Bromo-o-cresol is a multifunctional building block. Its aryl bromide group undergoes palladium-catalyzed cross-coupling reactions (e.g., Suzuki–Miyaura, Negishi, Buchwald–Hartwig). The phenolic hydroxyl can be O-alkylated, O-acylated, or used in metal coordination. The benzylic methyl group can be oxidized or halogenated for further diversification.

How should 6-Bromo-o-cresol be stored to maintain its stability?

The compound should be stored in a tightly sealed container, protected from light and moisture, and kept away from strong oxidizers and bases. Storage at 2–8 °C or as specified on the product label is recommended. Always consult the product's Safety Data Sheet (SDS) for detailed storage requirements.

Is 6-Bromo-o-cresol the same compound as 2-bromo-6-methylphenol?

Yes. 6-Bromo-o-cresol and 2-bromo-6-methylphenol are the same compound described by different naming conventions. The common name reflects the position (6) on the ortho-cresol ring, while the IUPAC name (2-bromo-6-methylphenol) uses systematic numbering. Both refer to CAS 6940-50-7.

What purity grades are available and how can I verify quality?

Aladdin Scientific offers 6-Bromo-o-cresol (SKU: B152683) as a research-grade reagent. Key quality indicators include assay purity by GC or HPLC, water content by Karl Fischer titration, and the absence of regioisomeric impurities. Certificates of analysis (CoA) are available upon request from Aladdin Scientific to support quality-assurance requirements.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 4th ed.; Wiley-Interscience: New York, 1992. (General reference for electrophilic aromatic substitution and phenol chemistry.)
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. (General reference for cross-coupling reactions and halogenated aromatic intermediates.)
3. Negishi, E. (Ed.) Handbook of Organopalladium Chemistry for Organic Synthesis; Wiley-Interscience: New York, 2002. (Reference for Pd-catalyzed cross-coupling reactions applicable to aryl bromide substrates.)

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