Iodoarenes to (diacetoxyiodo)arenes w/ potassium persulfate

Lego · Tue Aug 09, 2005 1:35 am

Alternative, Easy Preparation of (Diacetoxyiodo)arenes from Iodoarenes Using Potassium Peroxodisulfate as the Oxidant
MD. DelwarHossain, Tsugio Kitamura
Synthesis, 2005, 12, 1932-1934
http://dx.doi.org/10.1055/s-2005-869962

(Diacetoxyiodo)arenes from Iodoarenes; General Procedure
K₂ S₂ O₈ (4 mmol) was slowly added portionwise over 10 min to a stirred solution of an iodoarene (1 mmol) in AcOH (5 mL) with concd H₂ SO₄ (4 mmol) or CF₃ SO₃ H (6 mmol) at r.t. (25 °C), and the mixture was stirred at r.t. until TLC analysis indicated completion of the reaction. In the case of 1,4-diiodobenzene, CH₂ Cl₂ (3 mL) was added (this ensured the complete dissolution of 1,4-diiodobenzene). The solution was then concentrated to half its volume by evaporation of AcOH under reduced pressure, and H₂ O (10 mL) was added. The resulting precipitate was collected by filtration, washed with H₂ O (10 mL), and dried in air. A second crop of product was obtained by extraction of the filtrate with CH₂ Cl₂ (3 × 10 mL) and the combined extracts were dried over anhyd Na₂ SO₄ ; after filtration the solution was concentrated under reduced pressure. The combined crude products were purified by recrystallization from AcOH–hexane.
In the case of 1-iodo-4-nitrobenzene, CF₃ SO₃ H (12 mmol) was used as a promoter and 1,2-dichloroethane (5 mL) was added to dissolve the substrate.

(Diacetoxyiodo)benzene; Large-Scale
K₂ S₂ O₈ (100 mmol) was slowly added portion-wise over 20 min to a stirred solution of an iodobenzene (5.10 g, 25 mmol) in AcOH (125 mL) with concd H₂ SO₄ (100 mmol) at r.t. (25 °C), and the mixture was stirred at r.t. for 4 h. The solution was then concentrated to half its volume by evaporation of AcOH under reduced pressure, and H₂ O (100 mL) was added. The precipitate formed was collected by filtration, washed with H₂ O (200 mL), and dried in air. A second crop of product was obtained by extraction of the filtrate with CH₂ Cl₂ (3 × 25 mL); the combined extracts were dried over anhyd Na₂ SO₄ , filtered, and concentrated under reduced pressure. The combined crude products were purified by recrystallization from AcOH–hexane; yield: 7.15 g (88.7%).