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Abstract:
Benzyl(triphenyl)phosphonium dichloroiodate (BTPPICl2), BnPh3P+(ICl2)−, is easily synthesized in a nearly quantitative yield by the addition of BnPh3P+Cl− to a CH2Cl2 solution of iodine monochloride (ICl). BnPh3P+Cl− can be prepared by the reaction of Ph3P and BnCl. The compound was characterized by physicochemical and spectroscopic methods (elemental analysis, FT-IR, and 1H-NMR). The use of phosphonium counterion improves the quality of the BTPPICl2 crystals. BTPPICl2 crystallizes in the monoclinic system, and its crystal and molecular structure has been determined at 100(1) K by X-ray diffraction. The structure was solved by the direct method and had refined R value of 0.0637 for 699 reflections (I>2σ(I)), space group P21/n with a=12.4700(3), b=13.2196(3), c=14.4580(3) Å, β=102.6340(10)°, V=2325.67(9) Å3, and Z=4. The I-atom is coordinated by two Cl-atoms as ligands in a linear geometry. This compound is a versatile reagent for the efficient and selective iodination of organic substrates, in particular of aromatic phenols to the corresponding iodo compounds, under mild conditions. To assess the generality of method, a wide variety of phenols with electron-donating and electron-withdrawing substituents were studied. BTPPICl2 is a mild iodination reagent, which offers a new avenue for an expeditious iodination of phenols. The inexpensive, relatively non-toxic reagent, and mild conditions are the positive features of the procedure and reagent.
