Investigations of Different Chemoselectivities in Primary, Secondary and Tertiary Amide Reactions with Sodium Borohydride

2006 ◽  
Vol 2006 (8) ◽  
pp. 1991-1999 ◽  
Author(s):  
Jie Ren ◽  
Liang-Chun Li ◽  
Ji-Kai Liu ◽  
Hua-Jie Zhu ◽  
Charles U. Pittman
Keyword(s):  
Sodium Borohydride ◽  
Tertiary Amide

Polysulfide-borohydride modification of southern pine alkaline pulping integrated with hydrothermal pre-extraction of hemicelluloses

TAPPI Journal ◽  
2011 ◽  
Vol 10 (7) ◽  
pp. 9-16
Author(s):  
SUNG-HOON YOON ◽  
HARRY CULLINAN ◽  
GOPAL A. KRISHNAGOPALAN
Keyword(s):  
Loblolly Pine ◽  
Sodium Borohydride ◽  
Kraft Pulping ◽  
Hot Water ◽  
Pulp Yield ◽  
Paper Strength ◽  
Southern Pine ◽  
Two Stage ◽  
Simultaneous Treatment ◽  
Process Modification

We studied three process modifications to investigate their effects on the property and yield recovery capabilities of kraft pulping integrated with hemicellulose pre-extraction of southern pine. Loblolly pine chips were pre-extracted with hot water until the sugar extraction yield reached the targeted value of 10% and then subjected to conventional and modified kraft pulping. Modification included polysulfide pretreatment; polysulfide-sodium borohydride dual pretreatment, and polysulfide followed by polysulfide-sodium borohydride dual pretreatment two-stage pretreatments prior to kraft pulping. In the first modification, about 5% of the lost pulp yield (total 7%) caused by hemicellulose pre-extraction could be recovered with 15%-20% polysulfide pretreatment. Complete recovery (7%) was achieved with simultaneous pretreatment using 15% polysulfide and 0.5% sodium borohydride with 0.1% anthraquinone in polysulfide-sodium borohydride dual pretreatment. Two-stage pretreatment using recycled 15% polysulfide followed by simultaneous treatment of 6% polysulfide and 0.4%–0.5% sodium borohydride with 0.1% anthraquinone also achieved 100% yield recovery. Continuous recycling of 15% polysulfide employed in the two-stage process modification maintained its yield protection efficiency in a repeated recycling cycle. No significant changes in paper strength were found in handsheets prepared from the three process modifications, except for a minor reduction in tear strength.

Synthesis and Characterization of Silver Nanoplates by a Seed-mediated Method

2019 ◽  
Vol 29 (3) ◽  
Author(s):  
Mai Ngọc Tuan Anh
Keyword(s):  
Hydrogen Peroxide ◽  
Silver Nanoparticles ◽  
Ascorbic Acid ◽  
Silver Nitrate ◽  
Sodium Borohydride ◽  
Trisodium Citrate ◽  
Synthesis And Characterization ◽  
Silver Nanoplates ◽  
Seed Mediated

Silver nanoplates (SNPs) having different size were synthesized by a seed-mediated method. The seeds -silver nanoparticles with 4 – 6 nm diameters were synthesized first by reducing silver nitrate with sodium borohydride in the present of Trisodium Citrate and Hydrogen peroxide. Then these seeds were developed by continue reducing Ag\(^+\) ions with various amount of L-Ascorbic acid to form SNPs. Our analysis showed that the concentratrion of L-Ascorbic acid, a secondary reducing agent, played an important role to form SNPs. In addition, the size and in-plane dipole plasmon resonance wavelenght of silver nanoplates were increased when the concentration of added silver nitrate increased. The characterization of SNPs were studied by UV-Vis, FE-SEM, EDS and TEM methods.

The synthesis of model lactones of cyclolignan type

1981 ◽  
Vol 46 (9) ◽  
pp. 2123-2128 ◽  
Author(s):  
Jiří Křepelka ◽  
Jiří Holubek
Keyword(s):  
Sodium Borohydride ◽  
Catalytic Hydrogenation ◽  
Dicarboxylic Acids ◽  
Inhibitory Effect ◽  
Experimental Animals

Lactones VI-IX were prepared on reduction of anhydrides of 4-aryl-1-methoxynaphthalene-2,3-dicarboxylic acids IV and V with sodium borohydride in methanol. Catalytic hydrogenation on platinum of lactones VIII and IX gave lactones with hydrogenated ring A, or A and C. Lactones XII and XIII were found to possess an inhibitory effect on the growth of the tumour S 37 in experimental animals.

scholarly journals Sodium borohydride (NaBH4) as a high-capacity material for next-generation sodium-ion capacitors

2021 ◽  
Vol 19 (1) ◽  
pp. 432-441
Author(s):  
Pawel Jeżowski ◽  
Olivier Crosnier ◽  
Thierry Brousse
Keyword(s):  
Energy Density ◽  
Sodium Borohydride ◽  
Metal Ion ◽  
High Capacity ◽  
Negative Electrode ◽  
Sodium Ion ◽  
Modern World ◽  
Next Generation ◽  
Good Efficiency ◽  
Voltage Range

Abstract Energy storage is an integral part of the modern world. One of the newest and most interesting concepts is the internal hybridization achieved in metal-ion capacitors. In this study, for the first time we used sodium borohydride (NaBH4) as a sacrificial material for the preparation of next-generation sodium-ion capacitors (NICs). NaBH4 is a material with large irreversible capacity of ca. 700 mA h g−1 at very low extraction potential close to 2.4 vs Na+/Na0. An assembled NIC cell with the composite-positive electrode (activated carbon/NaBH4) and hard carbon as the negative one operates in the voltage range from 2.2 to 3.8 V for 5,000 cycles and retains 92% of its initial capacitance. The presented NIC has good efficiency >98% and energy density of ca. 18 W h kg−1 at power 2 kW kg−1 which is more than the energy (7 W h kg−1 at 2 kW kg−1) of an electrical double-layer capacitor (EDLC) operating at voltage 2.7 V with the equivalent components as in NIC. Tin phosphide (Sn4P3) as a negative electrode allowed the reaching of higher values of the specific energy density 33 W h kg−1 (ca. four times higher than EDLC) at the power density of 2 kW kg−1, with only 1% of capacity loss upon 5,000 cycles and efficiency >99%.

scholarly journals Reduction of the beta-Cys-gamma-Glu thiol ester bond of human C3 with sodium borohydride.

1983 ◽  
Vol 258 (22) ◽  
pp. 13580-13586 ◽  
Author(s):  
M L Thomas ◽  
F F Davidson ◽  
B F Tack
Keyword(s):  
Sodium Borohydride ◽  
Ester Bond ◽  
Thiol Ester

scholarly journals Surfactant-free synthesis of carbon-supported silver (Ag/C) nanobars as an efficient electrocatalyst for alcohol tolerance and oxidation of sodium borohydride in alkaline medium

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Santanu Dey ◽  
Pradipta Chakraborty ◽  
Dhiraj Kumar Rana ◽  
Subhamay Pramanik ◽  
Soumen Basu
Keyword(s):  
Cyclic Voltammetry ◽  
Ethylene Glycol ◽  
Alkaline Medium ◽  
Sodium Borohydride ◽  
Metallic Silver ◽  
Alcohol Tolerance ◽  
Current Ratio ◽  
X Ray ◽  
Scan Rate ◽  
Borohydride Oxidation

AbstractWe have synthesized carbon-supported silver (Ag/C) nanobars by a simple surfactant-free hydrothermal method using glucose as the reducing reagent as well as the source of carbon in Ag/C nanobars. Physicochemical characterization of the materials was performed by X-ray Diffraction (XRD), field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The XRD pattern confirmed the presence of a pure metallic silver phase. No carbon phase was detected, which indicates that the carbon exists mainly in the amorphous form. The electrocatalytic activity of Ag/C in different electrolyte solutions such as 0.5 M NaOH, 0.5 M NaOH + 1 M ethanol (EtOH), 0.5 M NaOH + 1 M ethylene glycol (EG), and 0.5 M NaOH + 0.01 M NaBH4 (sodium borohydride) was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) study. Alcohol tolerance of the catalysts was also established in the presence of ethanol and ethylene glycol. The forward-to-backward current ratio from cyclic voltammetry (CV) study of Ag/C-20 (20 h) in 0.5 M NaOH + 1 M ethanol solution at 100 mV s−1 scan rate is 4.13 times higher compared to that of Ag/C-5 (5 h). Hence, Ag/C-20 is a better candidate for the tolerance of ethanol. In the presence of ethylene glycol (1 M) in 0.5 M NaOH solution, it is obtained that the forward-to-backward current ratio at the same scan rate for Ag/C-20 is lower than that in the presence of ethanol. The durability of the catalyst was studied by chronoamperometry measurement. We studied the electrochemical kinetics of Ag/C catalysts for borohydride oxidation in an alkaline medium. The basic electrochemical results for borohydride oxidation show that Ag/C has very well strength and activity for direct borohydride oxidation in an alkaline medium. The reaction of borohydride oxidation with the contemporaneous BH4−. hydrolysis was noticed at the oxidized silver surface. Among all the synthesized Ag/C catalysts, Ag/C-20 exhibited the best electrocatalytic performance for borohydride oxidation in an alkaline medium. The activation energy and the number of exchange electrons at Ag/C-20 electrode surface for borohydride electro-oxidation were estimated as 57.2 kJ mol−1 and 2.27, respectively.

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