1: Br2 / acetic acid / 4 h / Heating 2: 1) NaNO2, conc. H2SO4; 2) amidosulfuric acid, HCl / 1) 2 h, r.t.; 2) water, 6 h View Scheme

1: 73 percent / Na2CO3 / acetonitrile / 48 h / Heating 2: 1) NaNO2, conc. H2SO4; 2) amidosulfuric acid, HCl / 1) 2 h, r.t.; 2) water, 6 h View Scheme

1: HCl / H2O / 8 h / pH = 1,5-3,5 2: 73 percent / Na2CO3 / acetonitrile / 48 h / Heating 3: 1) NaNO2, conc. H2SO4; 2) amidosulfuric acid, HCl / 1) 2 h, r.t.; 2) water, 6 h View Scheme

hydrogenchloride; sulfuric acid; aminosulfonic acid; sodium nitrite 1) 2 h, r.t.; 2) water, 6 h; Yield given. Multistep reaction;