2-Bromo-3-Hydroxybenzonitrile: Handling & Synthetic Use Protocol

2-Bromo-3-hydroxybenzonitrile is a versatile halogenated aromatic building block featuring orthogonal reactive sites—an aryl bromide, a phenolic hydroxyl, and a nitrile group—enabling selective derivatization in multi-step synthetic workflows.

CAS Number

To be confirmed (review_flag: CAS not provided in source material)

Molecular Formula

C7H4BrNO

Molecular Weight

198.02 g/mol

SKU

B194615

Functional Groups

Aryl bromide, phenolic hydroxyl (–OH), nitrile (–CN)

Recommended Storage

Cool, dry, dark conditions; store under inert atmosphere after opening (review_flag: confirm exact storage temperature from SDS)

Safety and Pre-Handling Considerations

Before working with 2-Bromo-3-hydroxybenzonitrile, consult the Safety Data Sheet (SDS) supplied by Aladdin Scientific (SKU B194615). Key precautions include:

• Personal Protective Equipment (PPE): Wear chemical-resistant gloves (nitrile recommended), a laboratory coat, and safety goggles at all times.
• Ventilation: Handle in a well-ventilated fume hood. The nitrile group poses an inhalation hazard; avoid generating dust or aerosols.
• Skin and Eye Contact: In case of contact, flush immediately with copious water for at least 15 minutes and seek medical advice.
• Waste Disposal: Dispose of all waste in accordance with local regulations for halogenated organic compounds.

Review flag: Specific GHS hazard classifications and H/P statements should be confirmed from the official Aladdin SDS for B194615 before use.

Materials and Equipment Required

The following materials are typically required for synthetic applications of 2-Bromo-3-hydroxybenzonitrile:

• 2-Bromo-3-hydroxybenzonitrile (Aladdin Scientific, SKU B194615)
• Appropriate palladium catalyst (e.g., Pd(PPh₃)₄ or Pd(dppf)Cl₂) for cross-coupling reactions
• Suitable base (e.g., K₂CO₃, Cs₂CO₃, or Et₃N depending on reaction type)
• Anhydrous solvent (e.g., DMF, THF, dioxane, or toluene) stored over molecular sieves
• Schlenk line or glovebox for air-sensitive manipulations
• Analytical balance (±0.1 mg precision)
• Magnetic stirrer and hotplate
• Thin-layer chromatography (TLC) plates and UV lamp for reaction monitoring
• Column chromatography materials (silica gel, appropriate eluent)
• Inert gas supply (N₂ or Ar)

Step-by-Step Protocol: Suzuki–Miyaura Cross-Coupling

2-Bromo-3-hydroxybenzonitrile serves as a convenient aryl bromide electrophile in palladium-catalyzed Suzuki–Miyaura cross-coupling. The free phenol may be protected or used directly depending on reaction conditions. The following general procedure outlines a representative coupling with an arylboronic acid:

1. Weigh reagents: Accurately weigh 2-Bromo-3-hydroxybenzonitrile (1.0 equiv) and the arylboronic acid coupling partner (1.2–1.5 equiv) into a dry Schlenk flask under inert atmosphere.
2. Add catalyst and base: Add Pd(PPh₃)₄ (2–5 mol%) and K₂CO₃ (2.0–3.0 equiv) to the flask.
3. Add solvent: Add degassed aqueous DMF (4:1 v/v) or dioxane/water mixture. Seal the flask and purge with N₂ or Ar for 10 minutes.
4. Heat and stir: Heat the reaction mixture to 80–100 °C with stirring for 12–18 hours, or until TLC indicates complete consumption of starting material.
5. Work-up: Cool to room temperature. Dilute with ethyl acetate (EtOAc), wash with water and brine, dry over anhydrous Na₂SO₄, filter, and concentrate under reduced pressure.
6. Purification: Purify the crude product by silica gel column chromatography using an appropriate hexane/EtOAc gradient.
7. Characterization: Confirm product identity and purity by ¹H NMR, ¹³C NMR, and HRMS.

Review flag: Specific temperature, solvent ratios, catalyst loading, and reaction times should be optimized empirically for each substrate pair. Values given are typical literature ranges and are not guaranteed for every substrate combination.

Phenol Protection and Selective Functionalization

The orthogonal reactivity of 2-Bromo-3-hydroxybenzonitrile makes it particularly valuable for multistep synthesis. The three functional groups can be addressed in sequence:

• Phenol protection: The –OH group can be protected as a methyl ether (using MeI/K₂CO₃ in DMF), a TBS silyl ether (TBSCl, imidazole, DCM), or a benzyl ether (BnBr, K₂CO₃) prior to metal-catalyzed coupling steps to avoid catalyst poisoning or unwanted side reactions.
• Nitrile transformation: The –CN group can be hydrolyzed to a carboxylic acid (aqueous NaOH or H₂SO₄, reflux), reduced to an amine (LiAlH₄ or BH₃·THF), or converted to a tetrazole via [3+2] cycloaddition with azide sources.
• C–Br bond functionalization: Besides Suzuki coupling, the aryl bromide undergoes Buchwald–Hartwig amination, Heck reaction, Negishi coupling, and halogen–metal exchange (n-BuLi, –78 °C) to generate aryllithium species for further electrophilic trapping.

Review flag: Specific reagent quantities, solvents, and conditions for each transformation must be sourced from primary literature or validated in-house prior to use. No specific yields or selectivities are claimed here.

Frequently asked questions

What is the recommended storage condition for 2-Bromo-3-hydroxybenzonitrile (B194615)?

Store 2-Bromo-3-hydroxybenzonitrile in a cool, dry, dark location away from incompatible materials such as strong bases and oxidizers. After opening, reseal tightly under an inert atmosphere (N₂ or Ar) to prevent moisture absorption and oxidation. Always consult the Aladdin SDS for confirmed storage temperature and shelf-life information.

Can the free phenol group of 2-Bromo-3-hydroxybenzonitrile interfere with palladium-catalyzed coupling reactions?

The free phenol can potentially coordinate to palladium or act as a nucleophile under certain conditions, leading to reduced catalyst efficiency or side products. In many Suzuki–Miyaura protocols, the phenol can be tolerated when mild bases are used; however, for sensitive reactions it is advisable to protect the hydroxyl group (e.g., as a methyl or silyl ether) before performing the cross-coupling step.

What analytical methods are suitable for confirming the purity of 2-Bromo-3-hydroxybenzonitrile?

Purity can be assessed by HPLC (reverse-phase C18 column, UV detection at 254 nm), GC (for volatile impurities), and melting point determination compared to literature values. Structural identity can be confirmed by ¹H NMR and ¹³C NMR spectroscopy, while HRMS provides exact mass confirmation. Aladdin Scientific's certificate of analysis (CoA) for SKU B194615 should be consulted for the reported purity specification.

Is 2-Bromo-3-hydroxybenzonitrile suitable for O-alkylation reactions?

Yes, the phenolic hydroxyl group of 2-Bromo-3-hydroxybenzonitrile can be selectively O-alkylated under standard conditions (e.g., alkyl halide and K₂CO₃ in DMF or acetone). Care should be taken to ensure that the aryl bromide and nitrile groups remain intact, particularly by avoiding strongly reducing or nucleophilic conditions. Review flag: specific selectivity data should be confirmed from primary literature.

References

1. Miyaura, N.; Suzuki, A. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chemical Reviews, 1995, 95(7), 2457–2483. doi:10.1021/cr00039a007
2. Hartwig, J. F. Transition Metal Catalyzed Synthesis of Arylamines and Aryl Ethers from Aryl Halides and Triflates: Scope and Mechanism. Angewandte Chemie International Edition, 1998, 37(15), 2046–2067. doi:10.1002/(SICI)1521-3773(19980817)37:15<2046::AID-ANIE2046>3.0.CO;2-L
3. Aladdin Scientific. Safety Data Sheet: 2-Bromo-3-hydroxybenzonitrile, SKU B194615. Aladdin Scientific Corp.

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