1,4-Diiodobenzene

1,4-Diiodobenzene appears as white to light orange crystals or powder. Its melting point is 131–132 °C, and it boils at 285 °C (sublimes). The compound is readily soluble in ether and ethanol, but insoluble in water.

1,4-Diiodobenzene is used in Suzuki reaction. It is used as a precursor in the preparation of martinellic acid and 1,4-bis(p-R-phenylethynyl)benzenes. Further, it is employed in the preparation of 1,4-diiodo-2,5-didodecylbenzene , which is a starting reagent for the synthesis of oligo(1,4-phenylene ethynylene). It is also used in human and animal nutrition products including antiseptics and disinfectants. In addition to this, it used in polarizing films for liquid crystal display chemicals.

1,4-Diiodobenzene is obtained by diazotising p-iodoaniline followed by substitution. An alternative preparation method involves diazotising p-phenylenediamine hydrochloride, followed by substitution with potassium iodide.

Crystallise it from EtOH or boiling MeOH, then dry it in air. [Beilstein 5 IV 700.]

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