hydrogen bromide; copper(I) bromide; sodium nitrite 1.) H2O, 0-5 deg C, 20 min, then 15-20 deg C, 15 min 2.) H2O, r.t., 30 min; Yield given. Multistep reaction. Yields of byproduct given;

With  dihydrogen peroxide in  methanol  1.) 0 deg C, 1 h, 2.) r.t., overnight;   

Multi-step reaction with 2 steps 1: 1.) conc. H2SO4, NaNO2 / 1.) ethanol, H2O, 0-5 deg C, 2.) ethanol, H2O, 80 deg C, 20 min2: 4 percent / Br2, Ag2SO4, conc. H2SO4 / Ambient temperature