4-Chloro-2-fluorophenylhydrazine HCl: Handling & Usage Guide

4-Chloro-2-fluorophenylhydrazine, HCl is a halogenated arylhydrazine hydrochloride salt widely employed as a versatile building block in the synthesis of pyrazoles, indazoles, and other nitrogen-containing heterocyclic scaffolds relevant to medicinal chemistry and agrochemical research.

Product Name

4-Chloro-2-fluorophenylhydrazine, HCl

SKU

C185760

Molecular Formula

C6H7Cl2FN2 (as HCl salt)

Chemical Class

Halogenated arylhydrazine hydrochloride

Primary Application

Building block for pyrazole, indazole, and heterocycle synthesis

Recommended Storage

Cool, dry place; sealed container; away from light and moisture

Physical Form

Solid (hydrochloride salt)

Chemical Identity and Properties

4-Chloro-2-fluorophenylhydrazine, HCl (SKU: C185760) is the hydrochloride salt of a substituted arylhydrazine bearing a chloro substituent at the 4-position and a fluoro substituent at the 2-position of the phenyl ring. The hydrochloride salt form enhances the stability and ease of handling compared with the free base. The compound is typically obtained as a solid at room temperature. The combination of electron-withdrawing chloro and fluoro groups on the aromatic ring modulates the nucleophilicity of the terminal hydrazine nitrogen atoms, making this reagent electronically distinct from unsubstituted phenylhydrazine and enabling selective reactivity in condensation and cyclization reactions.

Key physicochemical considerations include its sensitivity to moisture and oxidizing conditions, which can lead to degradation of the hydrazine functionality. Researchers should verify exact molecular weight, melting point, and purity specifications from the Certificate of Analysis (CoA) supplied with each lot.

Synthesis Applications and Reaction Scope

Arylhydrazines such as 4-Chloro-2-fluorophenylhydrazine, HCl serve as pivotal intermediates in heterocyclic chemistry. The principal synthetic utilities include:

• Pyrazole Synthesis: Condensation of the arylhydrazine with 1,3-dicarbonyl compounds or enones yields substituted pyrazoles, a scaffold of broad importance in pharmaceutical and agrochemical discovery programs.
• Indazole Formation: Cyclization sequences using appropriately functionalized aldehydes or ketones can afford N-aryl indazole derivatives bearing the 4-chloro-2-fluorophenyl motif.
• Fischer Indole Synthesis: Under acidic conditions, arylhydrazines react with ketones via the Fischer indole mechanism; the fluorine and chlorine substituents influence regioselectivity and reaction rate.
• Knorr-Type Pyrrole Synthesis: Reaction with β-keto esters under controlled conditions provides N-aryl pyrroles.

The presence of both halogen substituents also renders the phenyl ring amenable to downstream cross-coupling reactions (e.g., Suzuki, Buchwald–Hartwig) on the intact heterocyclic product, expanding the accessible chemical space from a single building block.

Safe Handling, Storage, and Disposal

Personal Protective Equipment (PPE): Always wear appropriate PPE when handling this compound, including nitrile gloves, laboratory coat, and safety goggles. Arylhydrazines and their salts are potential sensitizers and may be harmful upon skin contact, inhalation, or ingestion. Work in a well-ventilated fume hood at all times.

Storage: Store the compound in a tightly sealed container in a cool (2–8 °C recommended), dry, and dark environment. Protect from moisture, heat, and oxidizing agents. Under appropriate conditions, the hydrochloride salt offers improved bench stability relative to the free base; however, extended exposure to air or humidity should be avoided to prevent oxidative degradation of the hydrazine group.

Stability: The hydrochloride salt is generally more stable than the corresponding free base. Nonetheless, users should monitor the compound for discoloration or changes in physical appearance, which may indicate degradation.

Disposal: Dispose of this compound and any contaminated materials in accordance with local, regional, and national regulations governing hazardous chemical waste. Do not pour down the drain. Consult your institution's Environmental Health and Safety (EHS) office for specific disposal procedures applicable to hydrazine-containing compounds.

First Aid: In case of skin or eye contact, flush thoroughly with water for at least 15 minutes and seek medical attention. If inhaled, move to fresh air immediately. Refer to the Safety Data Sheet (SDS) for complete hazard information.

Quality, Purity, and Procurement Guidance

For research applications requiring reproducibility, selecting a reagent-grade or higher purity specification is strongly recommended. Aladdin Scientific supplies 4-Chloro-2-fluorophenylhydrazine, HCl (SKU: C185760) with a Certificate of Analysis (CoA) documenting lot-specific purity data typically assessed by techniques such as HPLC or titration. Researchers should:

• Request and review the CoA for each lot prior to use, paying attention to purity percentage, appearance, and water content (especially relevant for hygroscopic hydrazine salts).
• Confirm the identity of the compound using NMR spectroscopy (¹H and ¹⁹F NMR are particularly informative given the fluorine substituent) or mass spectrometry upon receipt if critical purity is required.
• For GMP-adjacent or regulated research, request additional documentation (e.g., residual solvents, heavy metals) as appropriate.

Procurement teams should note that hydrazine-containing compounds may be subject to additional regulatory scrutiny during import and export in certain jurisdictions. Aladdin Scientific's customer service team can assist with documentation and compliance queries.

Regulatory and Compliance Considerations

Hydrazine derivatives, including arylhydrazine salts, are subject to regulatory oversight in many countries due to their potential health hazards. Researchers and procurement professionals should be aware of the following:

• GHS Classification: This compound is expected to carry GHS hazard classifications related to acute toxicity, skin and respiratory sensitization, and potential genotoxicity of the hydrazine moiety. Always consult the current SDS before use.
• REACH (EU): Facilities in the European Union should verify compliance with REACH registration requirements for hydrazine-containing substances.
• Export Controls: Some hydrazine compounds are controlled for export in certain jurisdictions. Confirm applicable export control classifications with your institution's compliance office before international shipment.
• Workplace Exposure Limits: Consult national occupational exposure limit databases for hydrazine derivatives and implement appropriate engineering controls and monitoring as required.

Aladdin Scientific provides Safety Data Sheets (SDS) for all products. Users are responsible for ensuring that their use of this compound complies with all applicable local laws and institutional policies.

Frequently asked questions

What is 4-Chloro-2-fluorophenylhydrazine, HCl used for in organic synthesis?

4-Chloro-2-fluorophenylhydrazine, HCl is primarily used as a building block for constructing nitrogen-containing heterocycles. It reacts with 1,3-dicarbonyl compounds to form pyrazoles, with carbonyl substrates in Fischer indole synthesis, and can participate in other condensation and cyclization reactions to yield indazoles and pyrroles bearing the 4-chloro-2-fluorophenyl group.

How should 4-Chloro-2-fluorophenylhydrazine, HCl be stored to maintain stability?

The compound should be stored in a tightly sealed container at 2–8 °C in a cool, dry, and dark environment, away from moisture, heat, and oxidizing agents. The hydrochloride salt form is inherently more stable than the free base, but prolonged exposure to air or humidity should be avoided to prevent degradation of the hydrazine functional group. Always check the specific storage recommendations on the product label and CoA.

What safety precautions are required when handling 4-Chloro-2-fluorophenylhydrazine, HCl?

Always handle this compound in a well-ventilated fume hood while wearing appropriate PPE including nitrile gloves, laboratory coat, and safety goggles. Arylhydrazine salts may be toxic, sensitizing, and potentially genotoxic. Consult the Safety Data Sheet (SDS) for complete hazard information, first-aid measures, and disposal requirements before use.

Why is the hydrochloride salt form preferred over the free base for laboratory use?

The hydrochloride salt of arylhydrazines is typically more stable, less prone to oxidative degradation, easier to handle gravimetrically as a solid, and more amenable to long-term storage than the corresponding free base. The salt form also reduces the volatility and often the acute hazard profile compared with free-base hydrazines, improving laboratory safety.

Can 4-Chloro-2-fluorophenylhydrazine, HCl be used in cross-coupling reactions?

The compound itself is primarily employed as a condensation/cyclization building block. However, once incorporated into a heterocyclic product, the aryl chloride moiety on the phenyl ring can serve as a handle for palladium-catalyzed cross-coupling reactions such as Suzuki–Miyaura or Buchwald–Hartwig coupling, enabling further diversification of the heterocyclic scaffold.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. Wiley-Interscience. General reference for arylhydrazine reactivity and Fischer indole synthesis.
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed. Oxford University Press. Reference for pyrazole and indazole synthesis from hydrazines.
3. Aladdin Scientific. Certificate of Analysis, 4-Chloro-2-fluorophenylhydrazine, HCl, SKU C185760. [Lot-specific document available upon request].
4. Aladdin Scientific. Safety Data Sheet, 4-Chloro-2-fluorophenylhydrazine, HCl, SKU C185760. [Available from Aladdin Scientific upon request].

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