Spontaneous hydrolysis of sodium borohydride in harsh conditions

Production of formic acid from CO2 reduction by means of potassium borohydride at ambient conditions

“…Prior to the addition of CO 2 , three distinct boron species were observed in the 11 B spectra. The dominating sharp upfield 1:4:6:4:1 quintet centered at À 41.8 ppm ( 1 J H-11B ¼80.61 Hz) corresponds to the borohydride BH 4 À anion whilst the smaller 1:3:3:1 quartet at À 13 ppm ( 1 J H-11B ¼ 87.29 Hz) represents the hydroxyborohydride species BH 3 OH À , the first intermediate on the borohydride hydrolysis pathway (Andrieux et al, 2011;Guella et al, 2006). The coupling constants of both species correlate well between the 1 H and 11 B spectra and with the previously reports (Ruman et al, 2007).…”

“…The overall reaction for the reduction of CO 2 with BH 4 À The borane formed after hydrogen evolution is then quickly hydrolyzed to the hydroxyborohydride intermediate seen as a 1:1:1:1 quartet at 2.3 ppm in the 1 H NMR spectra and a 1:3:3:1 quartet at À13 ppm in the 11 B spectrum ( 1 J H-11B ¼ 80.6 Hz) (Andrieux et al, 2011;Churikov et al, 2012). Reports by Ruman et al (2007) and Reed and Jolly (1977) indicate that this ordinarily short lived species may in fact be more reactive than BH 4 À itself, and we therefore believe that this is the species responsible for the reduction of dissolved CO 2 .…”

Hydrolysis of Ammonia Borane as a Hydrogen Source: Fundamental Issues and Potential Solutions Towards Implementation

“…[53] Solution-state 11 B NMR spectroscopy and powder XRD established that the byproducts are B(OH) 4 À and NaBO 2 ·2 H 2 O. [54] The problem related to the hydration of the metaborate is also encountered in the hydrolysis of AB.…”

“…In the hydrolysis of SB, there is no ambiguity in the nature of the byproduct in aqueous solutions; typically, BH 4 À transforms to B(OH) 4 À , [54,57] and at pH < 9, B(OH) 3 predominates, whereas at pH > 9, mainly B(OH) 4 À forms. [50] However, upon drying at < 110 8C, the species present are primarily NaBO 2 ·2 H 2 O and NaBO 2 ·4 H 2 O.…”

CO 2 -promoted hydrolysis of KBH 4 for efficient hydrogen co-generation

“…Aqueous solutions of NaBH 4 are usually chemically stabilized by rendering solutions basic and do not generate significant amounts of H 2 under ambient conditions [22]. However, NaBH 4 hydrolysis rate can be dramatically accelerated upon the addition of certain heterogeneous catalysts [23,24]. Among the conventional catalysts studied for the reaction, ruthenium-based catalysts were proposed to be most effective for promoting H 2 generation [25,26].…”