(2-Bromo-5-fluorophenyl)hydrazine HCl: Use & Handling Guide

(2-Bromo-5-fluorophenyl)hydrazine hydrochloride is a halogenated arylhydrazine salt widely employed as a reactive building block in medicinal and synthetic chemistry, particularly for the construction of nitrogen-containing heterocyclic scaffolds.

Chemical Name

(2-Bromo-5-fluorophenyl)hydrazine hydrochloride

SKU

B194150

Molecular Formula

C₆H₇BrClFN₂

Key Functional Groups

Arylhydrazine (–NHNH₂·HCl), aryl bromide, aryl fluoride

Primary Application

Building block for Fischer indole synthesis and heterocyclic compound preparation

Recommended Storage

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

Handling Precaution

Use in a fume hood; wear appropriate PPE including gloves, lab coat, and eye protection

Chemical Identity and Key Properties

(2-Bromo-5-fluorophenyl)hydrazine hydrochloride (SKU B194150) is the hydrochloride salt of an arylhydrazine bearing both a bromine substituent at the ortho position and a fluorine substituent at the para position relative to the hydrazine group. The molecular formula is C₆H₇BrClFN₂. Conversion to the free base form is achieved by treatment with a mild inorganic base prior to use in reactions sensitive to the HCl counterion.

The simultaneous presence of two halogen substituents (Br and F) on the aromatic ring makes this compound particularly valuable: the C–Br bond is amenable to palladium-catalyzed cross-coupling reactions (e.g., Suzuki, Buchwald–Hartwig), while the C–F bond can modulate electronic density and metabolic stability in drug candidates. The hydrazine moiety serves as the reactive handle for condensation with carbonyl compounds.

Applications in Synthetic and Medicinal Chemistry

Fischer Indole Synthesis: Arylhydrazines are classical precursors for the Fischer indole synthesis, in which the hydrazine condenses with a ketone or aldehyde under acid catalysis to form an indole ring system. (2-Bromo-5-fluorophenyl)hydrazine hydrochloride can deliver 5-bromo-2-fluoro- or regioisomerically related indole scaffolds depending on the carbonyl substrate, enabling downstream diversification via cross-coupling.

Pyrazole and Pyrazoline Formation: Reaction of arylhydrazines with 1,3-dicarbonyl compounds or α,β-unsaturated carbonyl compounds provides pyrazoles or pyrazolines, respectively, which are privileged scaffolds in medicinal chemistry programs targeting kinases, COX enzymes, and other therapeutic targets.

Cross-Coupling Handle: The aryl bromide functionality retained in the product allows further elaboration through Pd-catalyzed coupling reactions, enabling rapid library synthesis from a single halogenated hydrazine precursor.

Safe Handling and Storage Protocol

Personal Protective Equipment (PPE): Always handle (2-Bromo-5-fluorophenyl)hydrazine hydrochloride wearing nitrile gloves, a laboratory coat, and chemical splash goggles. Hydrazine derivatives are generally considered irritants and potential sensitizers; minimise skin and eye contact.

Ventilation: All weighing, dissolution, and reaction steps must be performed inside a well-functioning chemical fume hood to avoid inhalation of dust or vapours.

Storage Conditions: Store the reagent in a tightly sealed container in a cool (2–8 °C or as specified on the product label), dry, and well-ventilated area away from incompatible materials such as strong oxidisers and strong acids (other than the stabilising HCl present as counterion). Protect from prolonged light exposure.

Waste Disposal: Dispose of all waste containing this compound in accordance with local and institutional regulations for halogenated organic waste. Do not pour down the drain.

First Aid: In case of skin or eye contact, flush immediately with copious water for at least 15 minutes and seek medical advice. If inhaled, move to fresh air immediately.

Preparation and Reaction Setup Guidelines

Dissolution: The hydrochloride salt is typically soluble in polar protic solvents such as water, methanol, and ethanol. For reactions requiring the free base, treat a solution of the salt with one equivalent of a mild base (e.g., triethylamine, sodium acetate, or potassium carbonate) before adding the carbonyl component.

Fischer Indole Protocol Outline:

1. Suspend or dissolve the hydrochloride salt (1.0 equiv) in ethanol or acetic acid.
2. Add the target ketone or aldehyde (1.0–1.2 equiv).
3. Add a catalytic or stoichiometric acid (p-TsOH, HCl, polyphosphoric acid) as appropriate for the substrate.
4. Heat the reaction mixture (typically 60–120 °C) until completion as monitored by TLC or HPLC.
5. Work up and purify by column chromatography or recrystallisation.

Pyrazole Protocol Outline:

1. Combine the free-base arylhydrazine (generated in situ) with a 1,3-diketone or β-ketoester (1.0 equiv) in ethanol.
2. Stir at room temperature to 80 °C; monitor by TLC.
3. Isolate and characterise the regioisomeric pyrazole product mixture by NMR and HPLC.

Optimise temperature, solvent, and acid/base loading empirically for each specific substrate combination.

Quality, Purity, and Specification Considerations

When ordering (2-Bromo-5-fluorophenyl)hydrazine hydrochloride (SKU B194150) from Aladdin Scientific, researchers should request the Certificate of Analysis (CoA) to confirm identity (typically by ¹H NMR or GC-MS), purity (HPLC or titration), and water content (Karl Fischer). For sensitive downstream reactions such as asymmetric catalysis or biological assays, a purity of ≥97% is generally recommended.

Batch-to-batch consistency is important for reproducible results. If long-term storage is required, aliquot the reagent into amber vials under inert atmosphere (nitrogen or argon) to minimise hydrolytic and oxidative degradation of the hydrazine moiety.

Contact Aladdin Scientific customer support for bulk quantities, custom purity grades, or specific analytical data requirements.

Frequently asked questions

What is the difference between (2-Bromo-5-fluorophenyl)hydrazine and its hydrochloride salt, and does it matter for my reaction?

The hydrochloride salt is a more stable, easier-to-handle crystalline solid compared to the free base, which can be hygroscopic or oily. For most condensation reactions (e.g., Fischer indole synthesis, pyrazole formation), the HCl counterion is either innocuous under acidic conditions or can be neutralised in situ with a mild base before the reaction. Always check your specific protocol for counterion compatibility.

How should I store (2-Bromo-5-fluorophenyl)hydrazine hydrochloride to maximise shelf life?

Store the reagent in a tightly closed container at 2–8 °C (or as indicated on the CoA), in a dry and well-ventilated area protected from light. For long-term storage, consider repackaging into smaller amber vials under nitrogen or argon to limit moisture ingress and oxidation of the hydrazine group. Always inspect for discolouration or clumping before use.

Can the aryl bromide in the product be used for further cross-coupling after the hydrazine has reacted?

Yes. The C–Br bond is orthogonal to the hydrazine condensation chemistry and typically survives standard Fischer indole or pyrazole cyclisation conditions. The resulting bromo-heterocycle can subsequently be engaged in Pd-catalysed Suzuki, Negishi, or Buchwald–Hartwig reactions, making this reagent a versatile two-step diversification handle.

What safety precautions are most important when working with this compound?

Work exclusively in a chemical fume hood to avoid inhalation of dust or vapours. Wear nitrile gloves, a lab coat, and splash goggles at all times. Hydrazine derivatives are potential irritants and sensitisers; treat all spills immediately and consult the Safety Data Sheet (SDS) for emergency procedures and waste disposal requirements.

How do I request a Certificate of Analysis or bulk pricing for SKU B194150?

Contact Aladdin Scientific customer service through the official website or by email, providing the SKU (B194150) and your required lot number or quantity. The CoA is typically available for download from the product page or can be requested directly from the technical support team.

References

1. Fischer, E.; Jourdan, F. Ueber die Hydrazine der Brenztraubensäure. Berichte der deutschen chemischen Gesellschaft, 1883.
2. Küenburg, B. et al. Development of a Scalable Synthesis of the Selective COX-2 Inhibitor Celecoxib Using Pyrazole-forming Reactions. Organic Letters, 1999.
3. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed. Oxford University Press, 2012. Chapter on heterocycle synthesis.

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