The reduction of nitrate and nitrite ions in basic solution with sodium borohydride in the presence of copper(II) ions

The reaction of NaNO3 and NaBH4 with added Cu(OH)(2) in 1 M NaOH at 65 degr eesC under Ar rapidly produced NH3, Cu metal, and H-2 with NO2- formed as a n intermediate. The overall equation describing the reaction is: Cu(OH)(2) + 3NO(3)(-) + 7BH(4)(-) + 20H(2)O --> Cu + 3NH(3) + 7B(OH)(4)(-) + 15H(2) + 30H(-) A direct reaction of NaNO2 with NaBH4 under the same conditions as those us ed with NaNO, follows the equation: Cu(OH)(2) + NO2- + 2BH(4)(-) + 5H(2)O --> Cu + 4H(2) + NH3 + 2B(OH)(4)(-) OH- The reductions of nitrate and nitrite with NaBH4 did not take place in basi c solution unless Cu(OH)(2) was present. (C) 2000 Elsevier Science B.V. All rights reserved.