2,6-Dichlorobenzyl bromide
[CAS# 20443-98-5]

Identification

• Classification: Organic raw materials >> Hydrocarbon compounds and their derivatives >> Hydrocarbon halide
• Name: 2,6-Dichlorobenzyl bromide
• Synonyms: alpha-Bromo-2,6-dichlorotoluene
• Molecular Formula: C₇H₅BrCl₂
• Molecular Weight: 239.92
• CAS Registry Number: 20443-98-5
• EC Number: 243-827-4
• SMILES: C1=CC(=C(C(=C1)Cl)CBr)Cl

Properties

• Density: 1.7±0.1 g/cm³ Calc.^*
• Melting point: 54 - 56 °C (Expl.)
• Boiling point: 260.9±25.0 °C 760 mmHg (Calc.)^*
• Flash point: 126.2±13.3 °C (Calc.)^*, 113 °C (Expl.)
• Index of refraction: 1.597 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS05;GHS07 Danger
• Risk Statements: H314-H335
• Safety Statements: P260-P261-P264-P271-P280-P301+P330+P331-P302+P361+P354-P304+P340-P305+P354+P338-P316-P319-P321-P363-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1B	H314
Specific target organ toxicity - single exposure	STOT SE	3	H335
Serious eye damage	Eye Dam.	1	H318
Substances or mixtures corrosive to metals	Met. Corr.	1	H290

• Transport Information: UN 3261

Discovery and Applications

2,6-Dichlorobenzyl bromide is an organic compound classified as a halogenated benzyl bromide derivative. It consists of a benzene ring substituted with two chlorine atoms at the 2- and 6-positions and a bromomethyl group (-CH₂Br) attached directly to the ring. This compound is recognized for its utility as an intermediate in organic synthesis, particularly in the preparation of biologically active molecules and specialty chemicals.

The discovery of 2,6-dichlorobenzyl bromide is closely linked to the broader development of halogenated aromatic compounds during the early 20th century. Research in aromatic substitution reactions, particularly electrophilic and nucleophilic substitutions involving chlorine and bromine, led to the identification and isolation of a wide range of halogenated benzyl bromides, including 2,6-dichlorobenzyl bromide. The synthesis typically involves the bromination of 2,6-dichlorotoluene under radical or electrophilic conditions, with reagents such as N-bromosuccinimide (NBS) in the presence of light or peroxides being commonly employed.

Applications of 2,6-dichlorobenzyl bromide span several fields, notably in medicinal chemistry, agrochemicals, and materials science. It serves as a key intermediate in the synthesis of pharmaceutical agents, particularly where a dichlorobenzyl moiety enhances biological activity. The compound has been used in the preparation of antimicrobial agents, exploiting the lipophilicity and electron-withdrawing properties of the dichloro substituents, which can improve the efficacy of therapeutic molecules against bacteria and fungi.

In agrochemical research, 2,6-dichlorobenzyl bromide has been utilized in the synthesis of herbicides, fungicides, and insecticides. Its chemical reactivity, particularly in nucleophilic substitution reactions, allows for the introduction of various functional groups, leading to a diverse array of bioactive compounds. The presence of electron-withdrawing chlorines on the aromatic ring enhances the reactivity of the benzylic bromide, facilitating its use in coupling reactions and as a precursor to more complex molecules.

The compound is also important in materials science for the modification of polymers and the synthesis of specialty resins. Its reactive bromomethyl group allows for grafting onto polymer backbones or the creation of crosslinked networks, providing materials with enhanced thermal stability, chemical resistance, or specific mechanical properties.

Handling of 2,6-dichlorobenzyl bromide requires caution, as benzyl bromides are generally known to be alkylating agents and can pose health hazards upon inhalation, ingestion, or skin contact. Proper safety measures, including the use of protective equipment and appropriate ventilation, are necessary when working with this chemical.

The chemical properties of 2,6-dichlorobenzyl bromide include moderate solubility in organic solvents such as chloroform, dichloromethane, and benzene. It is relatively stable under standard storage conditions but can hydrolyze slowly in the presence of moisture, leading to the formation of the corresponding benzyl alcohol derivative.

Industrial production methods for 2,6-dichlorobenzyl bromide typically involve controlled bromination processes that optimize selectivity for the desired bromomethyl product while minimizing over-bromination or side reactions. Purification is commonly achieved through distillation or recrystallization techniques to ensure the chemical's suitability for further synthesis steps.

The established use of 2,6-dichlorobenzyl bromide as a versatile synthetic building block continues to support its role in research and development across multiple industries, reflecting its well-characterized chemical behavior and functional importance.

References

2012. α-Bromo-2,6-dichlorotoluene: Molecular structure, vibrational spectroscopy, natural bond orbital analysis and NMR studies. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 95.
DOI: 10.1016/j.saa.2012.04.071

2008. An Expedient Three-Component Approach to the Synthesis of α,α-Disubstituted Amines under Barbier-like Conditions. Synlett, 2008(6).
DOI: 10.1055/s-2008-1072582

2020. Biological macromolecule binding and anticancer activity of synthetic alkyne-containing L-phenylalanine derivatives. Amino Acids, 52(5).
DOI: 10.1007/s00726-020-02849-w