Potassium Hydroxide → Ranisen

To a stirred mixture of 5-[(dimethylamino)methyl]-2-furanmethane-thiol oxalate (1:1) (1.31 g) and N-(2-chloroethyl)-N'-methyl-2-nitro-1,1-ethenediamine (1.08 g) in water (20 ml) at 45° under an atmosphere of nitrogen was added a solution of potassium hydroxide (1.04 g) in water (3 ml). The solution was stirred at 45° for 2.5 hr. and at room temperature for 15 hr. The solution was then evaporated in vacuo, the residue dissolved in water and a stream of air passed into the mixture for 15 mins. The mixture was extracted with ether (2×15 ml) and the aqueous fraction evaporated in vacuo. To the residue was added tetrahydrofuran (70 ml), an excess of anhydrous sodium carbonate, and decolourising charcoal. After 1 hr the mixture was filtered, the filtrate evaporated in vacuo and the oily residue dissolved in 4-methyl-pentan-2-one (8 ml). The solid which separated was filtered and washed with 4-methylpentan-2-one to give the title compound (0.72 g), m.p. 63°-66°, which was not depressed on admixture with a sample prepared according to the method of Example 15 in British Patent No. 1,565,966.