Sodium borohydride efficiently removes copper from amino acid–copper complexes

Effect of experimentally induced reducing conditions on the mobility of arsenic from a mining soil

“…A contact time of 48 h was used for the extractions with sodium borohydride. This contact time has been shown for aqueous solutions to provide adequate measurement of equilibrium [40] and is significantly greater than the contact time necessary for complete reaction with sodium borohydride [25]. A contact time of 10 days was used for the extractions with sodium ascorbate because of the slow reductive kinetics of this reagent [7,14].…”

“…Davranche et al [7][8][9]23] reported the use of hydroxylamine hydrochloride and sodium ascorbate to study the effect of reductive dissolution on the mobility of heavy metals (i.e., Pb, Cd, Zn) from slag and synthesized and natural iron and manganese oxyhydroxides [10,11,13,14]. The use of sodium borohydride has been reported for the precipitation of cobalt by reduction [24], removal of copper from amino acid complexes [25], as well as for the extraction of copper, lead, and zinc from soil samples in combination with a chelant (EDTA or citric acid) [26].…”

Metal Complexes of Biologically Important Ligands, CLXXII [1]. Metal Ions and Metal Complexes as Protective Groups of Amino Acids and Peptides – Reactions at Coordinated Amino Acids

“…Recently the use of sodium sulfide [111] and of sodium tetrahydridoboranate (reduction of Cu(II) to copper(I) oxide as precipitate) [112] was demonstrated with many examples for the removal of copper from amino acid copper complexes. Both methods proceed with high yields at ambient temperature and without racemization, and thus appear to be attractive.…”

Recent methodologies mediated by sodium borohydride in the reduction of different classes of compounds

“…59 The literature describes many different reagents used for this purpose, such as hydrogen sulfide, potassium cyanide, HCl, HBr, thioacetamide, 8-quinolinol, metal ion exchange resins and EDTA, which is the most widely used. However, the use of NaBH 4 is an important contribution because it is simple, nontoxic, inexpensive, the amino acids are furnished in high yield, purity and without racemization.…”

“…However, the use of NaBH 4 is an important contribution because it is simple, nontoxic, inexpensive, the amino acids are furnished in high yield, purity and without racemization. 59 This new method was based on reducing the amino acid-copper complexes into the insoluble copper(I), which was filtered and washed with water, releasing the free amino acid. Coster and co-workers have described the regioselective reduction of 3-methoxymaleimide and N-alkyl 3methoxymaleimides derivatives using NaBH 4 in THF-H 2 O at 0 • C (Table 7).…”