Cas No: 85118-00-9 | 2,6-difluorobenzyl Bromide

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Understanding 2,6-Difluorobenzyl Bromide (CAS No: 85118-00-9): Structure, Properties, and Applications
In the vast world of organic chemistry, halogenated benzyl derivatives play an essential role in synthetic chemistry, pharmaceutical intermediates, and material science. One such compound, 2,6-Difluorobenzyl bromide (CAS No: 85118-00-9), stands out for its unique combination of chemical reactivity and structural characteristics. This compound serves as a versatile building block in a range of chemical syntheses and research applications.

Chemical Identity and Structure
Chemical Name: 2,6-Difluorobenzyl bromide
CAS Number: 85118-00-9
Molecular Formula: C₇H₅BrF₂
Molecular Weight: 223.01 g/mol
IUPAC Name: (2,6-Difluorophenyl)methyl bromide
Structurally, the compound consists of a benzene ring substituted with two fluorine atoms at the ortho positions (positions 2 and 6) and a bromomethyl (-CH₂Br) group attached to the ring. This arrangement combines the electronic effects of fluorine atoms with the reactivity of a benzylic bromide, making it particularly useful in nucleophilic ...
... substitution reactions and as an intermediate in organic synthesis.
Physical and Chemical Properties
2,6-Difluorobenzyl bromide is typically a colorless to pale yellow liquid, depending on purity and storage conditions. Like many halogenated organic compounds, it possesses a sharp, characteristic odor and is sensitive to moisture and prolonged exposure to light.
Some of its general properties include:
Boiling Point: Approximately 195–200°C

Melting Point: Below room temperature (liquid at ambient conditions)

Density: Around 1.65 g/cm³

Refractive Index: Approximately 1.530–1.540

Solubility: Insoluble in water; soluble in common organic solvents such as dichloromethane, chloroform, and ether.

These properties reflect its relatively high molecular weight and the presence of halogens, which increase its density and refractive index compared to non-halogenated analogs.
Synthesis and Preparation
2,6-Difluorobenzyl bromide can be synthesized through several established methods. One common route involves the bromination of 2,6-difluorotoluene using bromine or N-bromosuccinimide (NBS) in the presence of a radical initiator such as benzoyl peroxide or azobisisobutyronitrile (AIBN). The reaction proceeds via a free-radical substitution mechanism, selectively targeting the benzylic hydrogen atom.
The general reaction can be represented as:
C₆H₃F₂CH₃ + Br₂ → C₆H₃F₂CH₂Br + HBr
Careful control of reaction conditions, such as temperature and light exposure, is crucial to ensure selectivity and to prevent over-bromination or degradation of the product.
Chemical Reactivity
As a benzyl bromide derivative, 2,6-Difluorobenzyl bromide exhibits significant electrophilic reactivity at the benzylic carbon. The carbon–bromine bond is polarized, allowing the bromine atom to act as a leaving group during substitution reactions.
Key reaction types include:
Nucleophilic Substitution (SN1/SN2):
It readily reacts with nucleophiles such as amines, thiols, or alkoxides to form corresponding benzyl derivatives like ethers, thioethers, or amines.

Grignard and Organolithium Reactions:
It can serve as a precursor for the generation of benzylmagnesium or benzyllithium intermediates, which are useful in carbon–carbon bond-forming reactions.

Cross-Coupling Reactions:
In modern synthetic chemistry, it may also be employed in transition-metal-catalyzed coupling reactions for constructing more complex aromatic or heteroaromatic compounds.

The presence of fluorine atoms at the 2 and 6 positions adds additional stability and electronic modulation. Fluorine’s high electronegativity can influence both the reactivity of the benzylic carbon and the compound’s lipophilicity, often enhancing its usefulness in medicinal chemistry.
Applications and Uses
2,6-Difluorobenzyl bromide is not typically used directly in consumer products but serves as a valuable intermediate in research and industry. Its major applications include:
1. Pharmaceutical Synthesis
This compound is a key intermediate in the synthesis of fluorinated aromatic compounds, which often exhibit enhanced metabolic stability and bioavailability. The difluoro substitution pattern can influence binding affinity in target molecules, making it an important fragment in the development of drug candidates.
2. Agrochemical Development
In agricultural chemistry, 2,6-Difluorobenzyl bromide can be used to prepare intermediates for herbicides, fungicides, and insecticides, where fluorinated groups improve efficacy and environmental stability.
3. Material Science and Polymers
Fluorinated aromatic compounds are increasingly explored for specialty polymers and coatings due to their chemical resistance and low surface energy. The compound’s reactive bromomethyl group allows easy incorporation into polymer backbones or side chains.
4. Chemical Research
In laboratory research, 2,6-Difluorobenzyl bromide is utilized as a reactive building block in the synthesis of novel molecules, especially when introducing fluorinated aromatic groups into complex organic frameworks.
Safety and Handling
Like many halogenated benzyl derivatives, 2,6-Difluorobenzyl bromide should be handled with care. It is corrosive and irritating to the skin, eyes, and respiratory system. Laboratory work should be performed in a well-ventilated fume hood while wearing appropriate protective clothing, gloves, and eyewear.
In case of contact or exposure, immediate rinsing with plenty of water and seeking medical attention is recommended. Proper storage in tightly sealed containers, away from light and moisture, helps maintain stability and minimize decomposition.
Conclusion
2,6-Difluorobenzyl bromide (CAS No: 85118-00-9) is a versatile and valuable reagent in modern organic synthesis. Its combination of fluorinated aromatic structure and reactive benzylic bromide functionality makes it a powerful intermediate for pharmaceuticals, agrochemicals, and materials research. While it demands careful handling due to its reactive nature, its utility in advancing chemical innovation continues to make it a compound of significant scientific interest.
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