1: 71 percent / ON(SO3K)2, 0.167M KH2PO4 / methanol; H2O / 2 h 2: 48 percent / NaNO2 / 3 h / Heating 3: 1.) ON(SO3K)2, 0.167 M K2HPO4, 2.) H2O / 1.) 4 h, 2.) 2 h, reflux View Scheme

With  potassium dihydrogenphosphate; Fremy’s salt in  methanol; water 2 h;   

Multi-step reaction with 2 steps 1: 71 percent / ON(SO3K)2, 0.167M KH2PO4 / methanol; H2O / 2 h2: 48 percent / NaNO2 / 3 h / Heating