8NaReO4 + 3Na[BH4] + 11HCl → 8ReO2 + 3H3BO3 + 11NaCl + 7H2O
Sodium perrhenate react with sodium tetrahydroxoborate(III) and hydrogen chloride to produce rhenium(IV) oxide, orthoboric acid, hydrogen chloride and water. This reaction takes place in the medium of ester.