2,4-Dinitrofluorobenzene
A highly activated fluoronitroaromatic supplied as Sanger's reagent for peptide and amino acid analysis and as an electrophile for selective substitution chemistry.
What is 2,4-Dinitrofluorobenzene?
2,4-Dinitrofluorobenzene — 24DNFB, known universally as Sanger's reagent — is a yellow low-melting solid carrying two nitro groups and a fluorine on one ring.
Two nitro groups working together make this fluorine extraordinarily reactive toward nucleophiles. It reacts with a free amino group at room temperature to give a stable, intensely yellow dinitrophenyl derivative, which is what allowed Frederick Sanger to identify the N-terminal residue of a peptide and, ultimately, to sequence insulin.
At Chelora Chemicals, 24DNFB is refined to reagent-grade purity with moisture controlled. Because the same reactivity that makes it useful also makes it a potent skin sensitiser, it is supplied only to industrial and laboratory users equipped to handle it.
- Appearance
- Yellow crystalline solid or liquid
- Odour
- Faint aromatic
- Solubility
- Insoluble in water; soluble in ethanol, ether, benzene
- Function
- Analytical reagent / chemical intermediate
- Grade
- Reagent / technical
Formula diagram
A fluorine activated by two nitro groups
- Molecular formulaC6H3FN2O4
- Molecular weight186.10 g/mol
- IUPAC name2,4-Dinitro-1-fluorobenzene
- Functional groupsNitro, aryl fluoride
- CAS number70-34-8
Technical product information
Standard specification for Chelora Chemicals' reagent and technical grade 2,4-Dinitrofluorobenzene. Custom-grade and bulk specifications are available on request.
| Chemical name | 2,4-Dinitrofluorobenzene |
|---|---|
| Synonyms | 24DNFB, DNFB, Sanger's reagent, 1-Fluoro-2,4-dinitrobenzene |
| CAS number | 70-34-8 |
| Molecular formula | C6H3FN2O4 |
| Molecular weight | 186.10 g/mol |
| Assay (GC purity) | ≥ 99.0% |
| Appearance | Yellow crystalline solid or liquid |
| Melting point | 25–27°C |
| Density (25°C) | 1.47–1.49 g/cm³ |
| Flash point | > 110°C (closed cup) |
| Water content | ≤ 0.1% |
| Packaging | 1 kg, 5 kg & 25 kg containers |
| Shelf life | 24 months in sealed original packaging |
Applications of 2,4-Dinitrofluorobenzene
Peptide N-terminal analysis
Reacts with free alpha-amino groups to give dinitrophenyl derivatives, the classical Sanger method for identifying terminal residues.
Amino acid derivatisation
Used to label and quantify amino acids and amines in analytical chemistry.
Immunology research
Applied as a defined hapten in contact hypersensitivity and immunological research models.
Selective substitution chemistry
Serves as a highly activated electrophile where mild, selective displacement is required.
Pharmaceutical intermediates
Used in synthesis routes that need a dinitrophenyl group installed on a nucleophile.
Analytical reagents
Supplied as a laboratory reagent for protein and amine chemistry.
Why choose Chelora Chemicals
Every batch of 2,4-Dinitrofluorobenzene is manufactured, tested, and documented to a standard that formulators and process chemists can build on with confidence — from first sample to full production volume.
Consistent purity
GC assay controlled at ≥99% with moisture and colour verified before dispatch.
Full documentation
COA, SDS, and regulatory data supplied with every shipment.
Flexible volumes
From 1 kg laboratory packs to 25 kg industrial containers.
Technical support
Process, handling, and compliance guidance from our chemistry team.
Storage and guidelines
- 01Store in tightly sealed original containers in a cool, dry, well-ventilated store.
- 02Expect the product to solidify below about 25°C; warm gently and evenly before transfer.
- 03Protect from moisture and light, and keep containers tightly closed at all times.
- 04Segregate from strong bases, amines, and reducing agents — reaction is rapid and exothermic.
- 05Use compatible containers: glass or lined steel; avoid contact with skin at every transfer point.
- 06Store in a locked or access-controlled area with clear sensitiser warning signage.
Handling precautions
24DNFB is toxic if swallowed or in contact with skin, causes severe skin burns and eye damage, and is a potent skin sensitiser. It is for industrial and laboratory use by trained personnel only.
This product is used experimentally precisely because it induces contact hypersensitivity. Once a person is sensitised, extremely small subsequent exposures can trigger a severe reaction, so preventing any first contact is the entire control strategy.
Double gloving with verified breakthrough resistance, coveralls, face protection, and work in a fume hood or fully enclosed system are the minimum. Gloves must be changed immediately on any suspected contact.
Reaction with amines and other nucleophiles is rapid and exothermic. Nitroaromatics carrying two nitro groups can also decompose energetically if overheated — never distil or dry this product at elevated temperature without a documented thermal assessment.
Any skin contact requires immediate, thorough washing and medical review even if there is no immediate pain or visible mark.
Refer to the full Safety Data Sheet for exposure limits, health surveillance, spill response, and first-aid measures before use.
Frequently asked questions
What is 2,4-Dinitrofluorobenzene used for?
Classically as Sanger's reagent for identifying the N-terminal amino acid of a peptide, and more broadly for derivatising amines in analytical work. It is also used as a highly activated electrophile in synthesis and as a defined hapten in immunology research.
Why is it called Sanger's reagent?
Frederick Sanger used it to determine the N-terminal residues of insulin, work that led to the first complete protein sequence and to his 1958 Nobel Prize. The reagent still carries his name.
Why is the fluorine so reactive here?
Two nitro groups, one ortho and one para, withdraw electron density powerfully and stabilise the intermediate formed when a nucleophile attacks. Under that double activation the fluorine is displaced by an amine at room temperature in mild conditions.
Why does it react with amino groups specifically?
Free amino groups are good nucleophiles at the pH used. The reaction gives a stable, strongly yellow dinitrophenyl derivative that survives the acid hydrolysis used to break the peptide apart, which is what makes the terminal residue identifiable afterwards.
What makes it such a strong sensitiser?
The same reactivity. It binds covalently to proteins in skin, and the immune system responds to that modified protein. This is why it is used deliberately in contact hypersensitivity research and why occupational exposure must be prevented rather than merely limited.
What PPE is required?
At minimum double gloves with verified breakthrough data, coveralls, face protection, and work in a fume hood or enclosed system. Gloves should be changed at once on any suspected contact, and skin contact needs immediate washing and medical review.
Is it a liquid or a solid?
It depends on temperature. The melting point is around 25–27°C, so it may arrive as a yellow solid or as a liquid. Warm gently and evenly rather than with a localised heat source.
Is it soluble in water?
No. It is insoluble in water and soluble in ethanol, ether, acetone, and benzene, which is why derivatisation protocols use organic or mixed solvent systems.
What purity do you supply?
Standard grade is supplied at a minimum GC assay of 99% with water at or below 0.1%. Reagent-grade specifications for analytical use can be produced to order.
What packaging sizes are available?
1 kg and 5 kg laboratory packs and 25 kg industrial containers. Supply is subject to confirmation of the receiving site's handling capability.
What are the thermal hazards?
Dinitroaromatics store considerable energy and can decompose energetically if overheated. Distillation, drying, or any heated processing requires a documented thermal risk assessment before it is attempted.
Do you provide a Certificate of Analysis?
Yes. Every batch is dispatched with a Certificate of Analysis and Safety Data Sheet covering GC assay, melting range, water content, and appearance.