The synthesis, reactivity and 1H NMR investigation of the hydroxyborohydride anion

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

“…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 broader signal at 2.3 ppm can be assigned to the borate B(OH) 4 À anion, which is the final product of both borohydride hydrolysis as well as the expected by-product of CO 2 reduction.…”

“…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 . Hydride attack of the electron deficient CO 2 carbon follows leading to the formation of a formate anion.…”

“…Due to the transitory nature of this BH 3 OH À species, it is normally only faintly observed, if at all, and as a consequence its reducing properties are relatively unknown. Of the few studies available (Molina Concha et al, 2011;Reed and Jolly, 1977;Ruman et al, 2007;Sanli et al, 2011;Santos and Sequeira, 2010), there are conflicting reports as to the reducing power of this species and as such further insight is greatly needed. While much research has already been devoted to hydrogen generation through borohydride hydrolysis, it is still somewhat doubtful if the reduction rate of CO 2 by the produced H 2 from borohydride hydrolysis is sufficiently high to produce high yield of formic acid and methanol.…”

Synthesis of methylene butyrolactone polymers from itaconic acid

“…The positive effect of the aqueous media on yield, as well as the relative ratio of water to THF, deserves discussion. For NaBH 4 , aqueous conditions can lead to the formation of NaB(OH)H 3 , a known intermediate in the stepwise hydrolysis of NaBH 4 . This hydroxyborohydride has been reported to reduce esters .…”

“…For NaBH 4 , aqueous conditions can lead to the formation of NaB(OH)H 3 , a known intermediate in the stepwise hydrolysis of NaBH 4 . This hydroxyborohydride has been reported to reduce esters . The varying ratios of water likely affect the rate of formation and stability of NaB(OH)H 3 .…”