1,5-Difluoro-3-methyl-2-nitrobenzene: Properties & Applications

1,5-Difluoro-3-methyl-2-nitrobenzene is a fluorinated nitroaromatic building block widely valued in medicinal chemistry and materials research for its dual electrophilic activation sites that enable selective nucleophilic aromatic substitution reactions.

IUPAC Name

1,5-Difluoro-3-methyl-2-nitrobenzene

SKU

D191275

Molecular Formula

C7H5F2NO2

Molecular Weight

173.12 g/mol

Key Functional Groups

Two aryl fluorides, one nitro group, one methyl group

Primary Application

Nucleophilic aromatic substitution (SNAr) intermediate

Chemical Structure and Properties

1,5-Difluoro-3-methyl-2-nitrobenzene (SKU D191275, molecular formula C₇H₅F₂NO₂, MW 173.12 g/mol) is a substituted benzene ring bearing two fluorine atoms at the 1- and 5-positions, a nitro group at the 2-position, and a methyl group at the 3-position. This combination of substituents creates a highly polarized aromatic system.

The electron-withdrawing nitro group acts synergistically with the two fluorine atoms to render the aromatic ring strongly electron-deficient. The ortho- and para-directing effects of the nitro group relative to each fluorine atom lower the LUMO energy of the ring, making both fluorine-bearing carbons susceptible to nucleophilic attack. The methyl group provides modest steric differentiation between the two fluorine sites, which can be exploited to achieve regioselective substitution.

Synthesis and Reactivity

The primary synthetic utility of 1,5-Difluoro-3-methyl-2-nitrobenzene lies in nucleophilic aromatic substitution (S_NAr). In S_NAr chemistry, aryl fluorides activated by electron-withdrawing groups such as nitro are among the most reactive leaving groups due to the high electronegativity of fluorine, which stabilizes the Meisenheimer complex intermediate.

Typical nucleophiles employed with this substrate include primary and secondary amines (yielding diarylamine or aminoaryl products), alkoxides (yielding aryl ethers), and thiolates (yielding aryl thioethers). Reaction conditions are generally mild—often room temperature to 80 °C in polar aprotic solvents such as DMF, DMSO, or NMP—making this building block operationally convenient for multi-step synthesis.

The nitro group itself is a handle for further diversification: catalytic hydrogenation or iron/acetic acid reduction converts it to a primary aniline, opening routes to diazotization, reductive amination scaffolds, or cyclization into heterocyclic systems such as benzimidazoles and indazoles.

Applications in Medicinal Chemistry and Materials Science

Fluorinated nitroaromatic intermediates like 1,5-Difluoro-3-methyl-2-nitrobenzene are extensively used in the pharmaceutical industry as building blocks for drug candidates. The incorporation of fluorine atoms into drug molecules is a well-established strategy to improve metabolic stability, membrane permeability, and binding affinity through favorable C–F···H–N or C–F···π interactions with biological targets.

This compound serves as a precursor for the synthesis of fluorinated anilines, diaryl ethers, and biaryl amines—structural motifs found in kinase inhibitors, antimicrobial agents, and CNS-active compounds. The methyl substituent adds lipophilicity and can participate in hydrophobic pocket interactions within enzyme active sites.

In materials science, electron-deficient fluorinated aromatics are used to prepare high-performance polymers, liquid crystal components, and organic semiconductors. The activated C–F bonds allow for polycondensation reactions to form poly(arylene ether) and related structures with desirable thermal and mechanical properties.

Handling, Storage, and Safety Considerations

As a nitroaromatic compound, 1,5-Difluoro-3-methyl-2-nitrobenzene should be handled with standard laboratory precautions appropriate for potentially irritating organic chemicals. Researchers should wear appropriate personal protective equipment including nitrile gloves, safety glasses, and a laboratory coat. Work should be conducted in a well-ventilated fume hood to avoid inhalation of dust or vapors.

The compound should be stored in a tightly sealed container in a cool, dry location away from strong reducing agents, bases, and sources of ignition. Nitroaromatic compounds can be sensitive to heat, shock, or friction under certain conditions, so storage away from incompatible materials is recommended.

Disposal must comply with local and institutional regulations for halogenated organic waste. Users are advised to consult the current Safety Data Sheet (SDS) for 1,5-Difluoro-3-methyl-2-nitrobenzene (D191275) available from Aladdin Scientific for specific hazard classifications, first-aid measures, and disposal guidance.

Frequently asked questions

What makes 1,5-Difluoro-3-methyl-2-nitrobenzene useful for SNAr reactions?

The nitro group at the 2-position is a powerful electron-withdrawing group that activates both aryl fluorines toward nucleophilic aromatic substitution by stabilizing the anionic Meisenheimer complex intermediate. Because fluorine is the best leaving group in SNAr due to its high electronegativity, this compound reacts efficiently with nitrogen, oxygen, and sulfur nucleophiles under mild conditions.

Can the nitro group in this compound be selectively reduced to an amine?

Yes. The nitro group in 1,5-Difluoro-3-methyl-2-nitrobenzene can be selectively reduced to the corresponding aniline using standard methods such as catalytic hydrogenation (H2/Pd-C) or chemical reduction with iron powder in acetic acid. Care should be taken to preserve the aryl C–F bonds during reduction by choosing appropriate conditions, as strong nucleophilic or basic conditions could promote competing SNAr side reactions.

What solvents and bases are recommended for reactions involving this building block?

Polar aprotic solvents such as DMF, DMSO, NMP, and acetonitrile are generally preferred for SNAr reactions with this substrate, as they stabilize the charged Meisenheimer intermediate without protonating the nucleophile. Mild inorganic bases such as K2CO3 or Cs2CO3 are commonly used when amine or alcohol nucleophiles require deprotonation. Reaction temperature typically ranges from ambient to 80 °C depending on nucleophile reactivity.

How should I store 1,5-Difluoro-3-methyl-2-nitrobenzene to maintain its integrity?

Store the compound in a tightly closed container under cool and dry conditions, away from light, heat, strong reducing agents, and incompatible bases. Always consult the current SDS provided by Aladdin Scientific for the most accurate and up-to-date storage and handling instructions specific to SKU D191275.

References

1. March, J.; Smith, M. B. March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 7th ed.; Wiley: Hoboken, NJ, 2013. (SNAr mechanistic discussion)
2. Meanwell, N. A. Synopsis of some recent tactical application of bioisosteres in drug design. J. Med. Chem. 2011, 54, 2529–2591. (Fluorine in medicinal chemistry) doi:10.1021/jm1013693
3. Bunnett, J. F.; Zahler, R. E. Aromatic nucleophilic substitution reactions. Chem. Rev. 1951, 49, 273–412.

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