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Dibromobenzene isomers Common name and systematic name 1,2-Dibromobenzene: 1,3-Dibromobenzene [1] 1,4-Dibromobenzene [2] [3] [4] Structure Molecular formula: C 6 H 4 Br 2: Molar mass: 235.906 g/mol Appearance colorless liquid colorless liquid white solid CAS number [583-53-9] [108-36-1] [106-37-6] Properties Density and phase: 1.9940 g/ml ...
1,2-Dibromobenzene (o-dibromobenzene) is an aryl bromide and isomer of dibromobenzene. It is one of three isomers, the others being 1,3- and 1,4-dibromobenzene. It is a colorless liquid, although impure samples appear yellowish. The compound is a precursor to many 1,2-disubstituted derivatives of benzene.
The most widely used synthetic route to DBA utilizes electrophilic borylation chemistry as the key transformation, [6] [7] which dates to 1969 from Seibert et al. [8] and 1998 from Eisch et al. [9] Starting with the commercially available chemical 1,2-dibromobenzene, lithium-halogen exchange [10] followed by silylation yields 1,2-bis(trimethylsilyl) benzene as the intermediate.
2 and triphenylphosphine (PPh 3 ), tetrabutylammonium iodide (TBAI) as a phase-transfer catalyst , and sodium hydroxide as a base. Below is an example reaction of 1,3-dibromobenzene to isophthalic acid .
2 → C 6 H 4 Cl 2 + HCl. The reaction also affords the 1,4- and small amounts of the 1,3-isomer. The 1,4- isomer is preferred over the 1,2- isomer due to steric hindrance. The 1,3- isomer is uncommon because it is a meta- compound, while chlorine, like all halogens, is an ortho/para-director in terms of electrophilic aromatic substitution.
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