Sulfuric Acid → p-Iodocumene

Participants

Reaction Conditions

Reaction Steps

4-Isopropylaniline (49.5 g, 366 mmol) is suspended in 200 ml of dist. water and admixed gradually under ice cooling with 200 ml of semiconcentrated sulphuric acid. Subsequently, a solution of sodium nitrite (25.5 g, 370 mmol) in 200 ml dist. water is added dropwise at such a rate that the temperature does not rise above 20° C. On completion of the dropwise addition, the mixture is stirred at 2° C. for another 20 min. The resulting clear reddish diazonium salt solution is now added through a filter to a solution of potassium iodide (135.0 g, 813 mmol) in 200 ml of dist. water. The reaction mixture is stirred at 80° C. for 1 h. In the course of this, the solution becomes black with vigorous gas evolution and an oily organic phase separates out. After cooling, the organic phase is removed and the aqueous phase is extracted four times more with 100 ml of ether. The combined organic phases are washed with dilute sodium hydroxide solution and dist. water, and dried over sodium sulphate. After the solvent has been removed, the crude product is distilled in a membrane-pump vacuum. The slightly reddish target product distils over at a temperature of 100-105° C. (15 mbar).

Provenance & Evidence