Sodium borohydride

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Sodium borohydride
Sodium borohydride.svg
Sodium borohydride.jpg
Sodium-3D.png
Borohydride-3D-vdW.png
Names
IUPAC name
Sodium tetrahydridoborate(1–)
Systematic IUPAC name
Sodium boranuide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.037.262 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 241-004-4
23167
MeSH Sodium+borohydride
PubChem CID
RTECS number
  • ED3325000
UNII
UN number 1426
  • InChI=1S/BH4.Na/h1H4;/q-1;+1 Yes check.svgY
    Key: YOQDYZUWIQVZSF-UHFFFAOYSA-N Yes check.svgY
  • InChI=1S/BH4.Na/h1H4;/q-1;+1
  • Key: YOQDYZUWIQVZSF-UHFFF
  • [Na+].[BH4-]
Properties
Na[BH4]
Molar mass 37.83 g·mol−1
Appearancewhite crystals
hygroscopic
Density 1.07 g/cm3 [1]
Melting point 400 °C (752 °F; 673 K)(decomposes) [1]
550 g/L [1]
Solubility soluble in liquid ammonia, amines, pyridine
Structure [2]
Cubic (NaCl), cF8
Fm3m, No. 225
a = 0.6157 nm
Thermochemistry [3]
86.8 J·mol−1·K−1
Std molar
entropy (S⦵298)
101.3 J·mol−1·K−1
−188.6 kJ·mol−1
−123.9 kJ·mol−1
Hazards
GHS labelling: [4]
GHS-pictogram-flamme.svg GHS-pictogram-skull.svg GHS-pictogram-silhouette.svg GHS-pictogram-acid.svg
Danger
H260, H301, H314, H360F
P201, P231+P232, P280, P308+P313, P370+P378, P402+P404
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
1
2
W
Flash point 70 °C (158 °F; 343 K)
ca.220 °C (428 °F; 493 K)
Explosive limits 3%
Lethal dose or concentration (LD, LC):
160 mg/kg (Oral – Rat)
230 mg/kg (Dermal – Rabbit)
Related compounds
Other anions
Sodium cyanoborohydride
Sodium hydride
Sodium borate
Borax
Sodium aluminum hydride
Other cations
Lithium borohydride
Related compounds
 Lithium aluminium hydride
Sodium triacetoxyborohydride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, [5] is an inorganic compound with the formula Na B H 4 (sometimes written as Na[BH4]). It is a white crystalline solid, usually encountered as an aqueous basic solution. Sodium borohydride is a reducing agent that finds application in papermaking and dye industries. It is also used as a reagent in organic synthesis. [6]

Contents

The compound was discovered in the 1940s by H. I. Schlesinger, who led a team seeking volatile uranium compounds. [7] [8] Results of this wartime research were declassified and published in 1953.

Properties

The compound is soluble in alcohols, certain ethers, and water, although it slowly hydrolyzes. [9]

SolventSolubility (g/(100 mL)) [9]
CH3OH 13
CH3CH2OH 3.16
Diglyme 5.15
(CH3CH2)2O insoluble

Sodium borohydride is an odorless white to gray-white microcrystalline powder that often forms lumps. It can be purified by recrystallization from warm (50 °C) diglyme. [10] Sodium borohydride is soluble in protic solvents such as water and lower alcohols. It also reacts with these protic solvents to produce H2; however, these reactions are fairly slow. Complete decomposition of a methanol solution requires nearly 90 min at 20 °C. [11] It decomposes in neutral or acidic aqueous solutions, but is stable at pH 14. [9]

Structure

NaBH4 is a salt, consisting of the tetrahedral [BH4]− anion. The solid is known to exist as three polymorphs: α, β and γ. The stable phase at room temperature and pressure is α-NaBH4, which is cubic and adopts an NaCl-type structure, in the Fm3m space group. At a pressure of 6.3 GPa, the structure changes to the tetragonal β-NaBH4 (space group P421c) and at 8.9 GPa, the orthorhombic γ-NaBH4 (space group Pnma) becomes the most stable. [12] [13] [14]

Synthesis and handling

For commercial NaBH4 production, the Brown-Schlesinger process and the Bayer process are the most popular methods. In the Brown-Schlesinger process sodium borohydride is industrially prepared from sodium hydride (produced by reacting Na and H2) and trimethyl borate at 250–270 °C:

B(OCH3)3 + 4 NaH → NaBH4 + 3 NaOCH3

Millions of kilograms are produced annually, far exceeding the production levels of any other hydride reducing agent. [15] In the Bayer process, it is produced from inorganic borates, including borosilicate glass [16] and borax (Na2B4O7):

Na2B4O7 + 16 Na + 8 H2 + 7 SiO2 → 4 NaBH4 + 7 Na2SiO3

Magnesium is a less expensive reductant, and could in principle be used instead: [17] [18]

8 MgH2 + Na2B4O7 + Na2CO3 → 4 NaBH4 + 8 MgO + CO2

and

2 MgH2 + NaBO2 → NaBH4 + 2 MgO

Reactivity

Organic synthesis

NaBH4 reduces many organic carbonyls, depending on the conditions. Most typically, it is used in the laboratory for converting ketones and aldehydes to alcohols. [6] These reductions proceed in two stages, formation of the alkoxide followed by hydrolysis:

NaBH4 + 4 R2C=O → NaO−CHR2 + B(O−CHR2)3
NaO−CHR2 + B(O−CHR2)3 + 4 H2O → 4 HO−CHR2 + NaOH + B(OH)3

It also efficiently reduces acyl chlorides, anhydrides, α-hydroxylactones, thioesters, and imines at room temperature or below. It reduces esters slowly and inefficiently with excess reagent and/or elevated temperatures, while carboxylic acids and amides are not reduced at all. [19]

Nevertheless, an alcohol, often methanol or ethanol, is generally the solvent of choice for sodium borohydride reductions of ketones and aldehydes. The mechanism of ketone and aldehyde reduction has been scrutinized by kinetic studies, and contrary to popular depictions in textbooks, the mechanism does not involve a 4-membered transition state like alkene hydroboration, [20] or a six-membered transition state involving a molecule of the alcohol solvent. [21] Hydrogen-bonding activation is required, as no reduction occurs in an aprotic solvent like diglyme. However, the rate order in alcohol is 1.5, while carbonyl compound and borohydride are both first order, suggesting a mechanism more complex than one involving a six-membered transition state that includes only a single alcohol molecule. It was suggested that the simultaneous activation of the carbonyl compound and borohydride occurs, via interaction with the alcohol and alkoxide ion, respectively, and that the reaction proceeds through an open transition state. [22] [23]

α,β-Unsaturated ketones tend to be reduced by NaBH4 in a 1,4-sense, although mixtures are often formed. Addition of cerium chloride improves the selectivity for 1,2-reduction of unsaturated ketones (Luche reduction). α,β-Unsaturated esters also undergo 1,4-reduction in the presence of NaBH4. [9]

The NaBH4-MeOH system, formed by the addition of methanol to sodium borohydride in refluxing THF, reduces esters to the corresponding alcohols. [24] Mixing water or an alcohol with the borohydride converts some of it into unstable hydride ester, which is more efficient at reduction, but the reductant eventually decomposes spontaneously to produce hydrogen gas and borates. The same reaction can also occur intramolecularly: an α-ketoester converts into a diol, since the alcohol produced attacks the borohydride to produce an ester of the borohydride, which then reduces the neighboring ester. [25]

The reactivity of NaBH4 can be enhanced or augmented by a variety of compounds. [26] [27]

Many additives for modifying the reactivity of sodium borohydride have been developed as indicated by the following incomplete listing.

Additives for sodium borohydride
additivesynthetic applicationspage in Smith and March [28] comment
AlCl3 reduction of ketones to methylene1837
BiCl3 converts epoxides to allylic alcohols1316
(C6H5Te)2 reduction of nitroarenes1862
CeCl3 reduction of ketones in the presence of aldehydes1794 Luche reduction
CoCl2 reduction of azides to amines1822
InCl3 hydrogenolysis of alkyl bromides, double reduction of unsaturated ketones1825, 1793
LiCl amine oxides to amines1846 lithium borohydride
NiCl2 deoxygenation of sulfoxides, hydrogenolysis of aryl tosylates, desulfurization, reduction of nitriles1851,1831, 991, 1814 nickel boride
TiCl4 denitrosatation of nitrosamines 1823
ZnCl2 reduction of aldehydes1793
ZrCl4 reduction of disulfides, reduction of azides to amines, cleavage of allyl aryl ethers1853, 1822, 582

Oxidation

Oxidation with iodine in tetrahydrofuran gives borane–tetrahydrofuran, which can reduce carboxylic acids to alcohols. [29]

Partial oxidation of borohydride with iodine gives octahydrotriborate: [30]

3 [BH4]− + I2 → [B3H8]− + 2 H2 + 2 I−

Coordination chemistry

[BH4]− is a ligand for metal ions. Such borohydride complexes are often prepared by the action of NaBH4 (or the LiBH4) on the corresponding metal halide. One example is the titanocene derivative: [31]

2 (C5H5)2TiCl2 + 4 NaBH4 → 2 (C5H5)2TiBH4 + 4 NaCl + B2H6 + H2

Protonolysis and hydrolysis

NaBH4 reacts with water and alcohols, with evolution of hydrogen gas and formation of the corresponding borate, the reaction being especially fast at low pH. Exploiting this reactivity, sodium borohydride has been studied as a prototypes of the direct borohydride fuel cell.

NaBH4 + 2 H2O → NaBO2 + 4 H2 (ΔH < 0)

Applications

Paper manufacture

The dominant application of sodium borohydride is the production of sodium dithionite from sulfur dioxide: Sodium dithionite is used as a bleaching agent for wood pulp and in the dyeing industry.

It has been tested as pretreatment for pulping of wood, but is too costly to be commercialized. [15] [32]

Chemical synthesis

Sodium borohydride reduces aldehydes and ketones to give the related alcohols. This reaction is used in the production of various antibiotics including chloramphenicol, dihydrostreptomycin, and thiophenicol. Various steroids and vitamin A are prepared using sodium borohydride in at least one step. [15]

Niche or abandoned applications

Sodium borohydride has been considered as a way to store hydrogen for hydrogen-fueled vehicles, as it is safer (being stable in dry air) and more efficient on a weight basis than most other alternatives. [33] [34] The hydrogen can be released by simple hydrolysis of the borohydride. However, such a usage would need a cheap, relatively simple, and energy-efficient process to recycle the hydrolysis product, sodium metaborate, back to the borohydride. No such process was available as of 2007. [35]

Although practical temperatures and pressures for hydrogen storage have not been achieved, in 2012 a core–shell nanostructure of sodium borohydride was used to store, release and reabsorb hydrogen under moderate conditions. [36]

Skilled professional conservator/restorers have used sodium borohydride to minimize or reverse foxing in old books and documents. [37]

See also

Many derivatives and analogues of sodium borohydride exhibit modified reactivity of value in organic synthesis. [38]

Related Research Articles

<span class="mw-page-title-main">Carboxylic acid</span> Organic compound containing a –C(=O)OH group

In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group attached to an R-group. The general formula of a carboxylic acid is often written as R−COOH or R−CO2H, sometimes as R−C(O)OH with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion.

<span class="mw-page-title-main">Diborane</span> Chemical compound

Diborane(6), commonly known as diborane, is the chemical compound with the formula B2H6. It is a toxic, colorless, and pyrophoric gas with a repulsively sweet odor. Given its simple formula, borane is a fundamental boron compound. It has attracted wide attention for its electronic structure. Several of its derivatives are useful reagents.

<span class="mw-page-title-main">Lithium aluminium hydride</span> Chemical compound

Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula Li[AlH4] or LiAlH4. It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids, and amides. The solid is dangerously reactive toward water, releasing gaseous hydrogen (H2). Some related derivatives have been discussed for hydrogen storage.

<span class="mw-page-title-main">Sodium hydride</span> Chemical compound

Sodium hydride is the chemical compound with the empirical formula NaH. This alkali metal hydride is primarily used as a strong yet combustible base in organic synthesis. NaH is a saline (salt-like) hydride, composed of Na+ and H− ions, in contrast to molecular hydrides such as borane, methane, ammonia, water, and hydrogen fluoride. It is an ionic material that is insoluble in all solvents (other than molten Na), consistent with the fact that H− ions do not exist in solution. Because of the insolubility of NaH, all reactions involving NaH occur at the surface of the solid.

<span class="mw-page-title-main">Sodium bis(2-methoxyethoxy)aluminium hydride</span> Chemical compound

Sodium bis(2-methoxyethoxy)aluminium hydride (SMEAH; trade names Red-Al, Synhydrid, Vitride) is a complex hydride reductant with the formula NaAlH2(OCH2CH2OCH3)2. The trade name Red-Al refers to its being a reducing aluminium compound. It is used predominantly as a reducing agent in organic synthesis. The compound features a tetrahedral aluminium center attached to two hydride and two alkoxide groups, the latter derived from 2-methoxyethanol. Commercial solutions are colorless/pale yellow and viscous. At low temperatures (below -60 °C), the solution solidifies to a glassy pulverizable substance with no sharp melting point.

In chemistry, transfer hydrogenation is a chemical reaction involving the addition of hydrogen to a compound from a source other than molecular H2. It is applied in laboratory and industrial organic synthesis to saturate organic compounds and reduce ketones to alcohols, and imines to amines. It avoids the need for high-pressure molecular H2 used in conventional hydrogenation. Transfer hydrogenation usually occurs at mild temperature and pressure conditions using organic or organometallic catalysts, many of which are chiral, allowing efficient asymmetric synthesis. It uses hydrogen donor compounds such as formic acid, isopropanol or dihydroanthracene, dehydrogenating them to CO2, acetone, or anthracene respectively. Often, the donor molecules also function as solvents for the reaction. A large scale application of transfer hydrogenation is coal liquefaction using "donor solvents" such as tetralin.

<span class="mw-page-title-main">Sodium cyanoborohydride</span> Chemical compound

Sodium cyanoborohydride is a chemical compound with the formula Na[BH3(CN)]. It is a colourless salt used in organic synthesis for chemical reduction including that of imines and carbonyls. Sodium cyanoborohydride is a milder reductant than other conventional reducing agents.

<span class="mw-page-title-main">Borohydride</span>

Borohydride refers to the anion [BH4]−, which is also called tetrahydridoborate, and its salts. Borohydride or hydroborate is also the term used for compounds containing [BH4−nXn]−, where n is an integer from 0 to 3, for example cyanoborohydride or cyanotrihydroborate [BH3(CN)]− and triethylborohydride or triethylhydroborate [BH(CH2CH3)3]−. Borohydrides find wide use as reducing agents in organic synthesis. The most important borohydrides are lithium borohydride and sodium borohydride, but other salts are well known. Tetrahydroborates are also of academic and industrial interest in inorganic chemistry.

<span class="mw-page-title-main">Aluminium hydride</span> Chemical compound

Aluminium hydride is an inorganic compound with the formula AlH3. Alane and its derivatives are part of a family of common reducing reagents in organic synthesis based around group 13 hydrides. In solution—typically in etherial solvents such tetrahydrofuran or diethyl ether—aluminium hydride forms complexes with Lewis bases, and reacts selectively with particular organic functional groups, and although it is not a reagent of choice, it can react with carbon-carbon multiple bonds. Given its density, and with hydrogen content on the order of 10% by weight, some forms of alane are, as of 2016, active candidates for storing hydrogen and so for power generation in fuel cell applications, including electric vehicles. As of 2006 it was noted that further research was required to identify an efficient, economical way to reverse the process, regenerating alane from spent aluminium product.

<span class="mw-page-title-main">Lithium borohydride</span> Chemical compound

Lithium borohydride (LiBH4) is a borohydride and known in organic synthesis as a reducing agent for esters. Although less common than the related sodium borohydride, the lithium salt offers some advantages, being a stronger reducing agent and highly soluble in ethers, whilst remaining safer to handle than lithium aluminium hydride.

<span class="mw-page-title-main">L-selectride</span> Chemical compound

L-selectride is a organoboron compound with the chemical formula Li[(CH3CH2CH )3BH]. A colorless salt, it is usually dispensed as a solution in THF. As a particularly basic and bulky borohydride, it is used for stereoselective reduction of ketones..

<span class="mw-page-title-main">Sodium aluminium hydride</span> Chemical compound

Sodium aluminium hydride or sodium alumanuide is an inorganic compound with the chemical formula NaAlH4. It is a white pyrophoric solid that dissolves in tetrahydrofuran (THF), but not in diethyl ether or hydrocarbons. It has been evaluated as an agent for the reversible storage of hydrogen and it is used as a reagent for the chemical synthesis of organic compounds. Similar to lithium aluminium hydride, it is a salt consisting of separated sodium cations and tetrahedral AlH−
4 anions.

Luche reduction is the selective organic reduction of α,β-unsaturated ketones to allylic alcohols. The active reductant is described as "cerium borohydride", which is generated in situ from NaBH4 and CeCl3(H2O)7.

<span class="mw-page-title-main">Aluminium borohydride</span> Chemical compound

Aluminium borohydride, also known as aluminium tetrahydroborate, is the chemical compound with the formula Al(BH4)3. It is a volatile pyrophoric liquid which is used as a reducing agent in laboratories. Unlike most other metal–borohydrides, which are ionic structures, aluminium borohydride is a covalent compound.

<span class="mw-page-title-main">Carbonyl reduction</span> Organic reduction of any carbonyl group by a reducing agent

In organic chemistry, carbonyl reduction is the conversion of any carbonyl group, usually to an alcohol. It is a common transformation that is practiced in many ways. Ketones, aldehydes, carboxylic acids, esters, amides, and acid halides - some of the most pervasive functional groups, -comprise carbonyl compounds. Carboxylic acids, esters, and acid halides can be reduced to either aldehydes or a step further to primary alcohols, depending on the strength of the reducing agent. Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation, the alcohol group can be further reduced and removed altogether by replacement with H.

Enantioselective ketone reductions convert prochiral ketones into chiral, non-racemic alcohols and are used heavily for the synthesis of stereodefined alcohols.

Reductions with metal alkoxyaluminium hydrides are chemical reactions that involve either the net hydrogenation of an unsaturated compound or the replacement of a reducible functional group with hydrogen by metal alkoxyaluminium hydride reagents.

<span class="mw-page-title-main">Sodium triacetoxyborohydride</span> Chemical compound

Sodium triacetoxyborohydride, also known as sodium triacetoxyhydroborate, commonly abbreviated STAB, is a chemical compound with the formula Na[(CH3COO)3BH]. Like other borohydrides, it is used as a reducing agent in organic synthesis. This colourless salt is prepared by protonolysis of sodium borohydride with acetic acid:

Nickel boride is the common name of materials composed chiefly of the elements nickel and boron that are widely used as catalysts in organic chemistry. Their approximate chemical composition is Ni2.5B, and they are often incorrectly denoted "Ni
2B" in organic chemistry publications.

<span class="mw-page-title-main">Potassium borohydride</span> Chemical compound

Potassium borohydride, also known as potassium tetrahydridoborate and potassium tetrahydroborate, is an inorganic compound with the formula KBH4. It was discovered together with sodium borohydride by Hermann Irving Schlesinger and his team in 1940s.

References

  1. 1 2 3 Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). CRC Press. p. 4.89. ISBN   978-1439855119.
  2. ↑ Ford, P. T. and Powell, H. M. (1954). "The unit cell of potassium borohydride, KBH4, at 90° K". Acta Crystallogr. 7 (8): 604–605. Bibcode:1954AcCry...7..604F. doi: 10.1107/S0365110X54002034 .{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ↑ CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data. William M. Haynes, David R. Lide, Thomas J. Bruno (2016-2017, 97th ed.). Boca Raton, Florida. 2016. ISBN   978-1-4987-5428-6. OCLC   930681942.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)
  4. ↑ Record of Sodium borohydride in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 2023-11-09.
  5. ↑ Busch, D.H. (2009). Inorganic Syntheses. Vol. 20. Wiley. p. 137. ISBN   9780470132869 . Retrieved 20 May 2015.
  6. 1 2 Banfi, Luca; Narisano, Enrica; Riva, Renata; Stiasni, Nikola; Hiersemann, Martin; Yamada, Tohru; Tsubo, Tatsuyuki (2014). "Sodium Borohydride". Encyclopedia of Reagents for Organic Synthesis. pp. 1–13. doi:10.1002/047084289X.rs052.pub3. ISBN   9780470842898.
  7. ↑ Schlesinger, H. I.; Brown, H. C.; Abraham, B.; Bond, A. C.; Davidson, N.; Finholt, A. E.; Gilbreath, J. R.; Hoekstra, H.; Horvitz, L.; Hyde, E. K.; Katz, J. J.; Knight, J.; Lad, R. A.; Mayfield, D. L.; Rapp, L.; Ritter, D. M.; Schwartz, A. M.; Sheft, I.; Tuck, L. D.; Walker, A. O. (1953). "New developments in the chemistry of diborane and the borohydrides. General summary". J. Am. Chem. Soc. 75: 186–90. doi:10.1021/ja01097a049.
  8. ↑ Hermann I Schlesinger and Herbert C Brown (1945) "Preparation of alkali metal compounds". US Patent 2461661. Granted on 1949-02-15; expired on 1966-02-15.
  9. 1 2 3 4 Banfi, L.; Narisano, E.; Riva, R.; Stiasni, N.; Hiersemann, M. (2004). "Sodium Borohydride". Encyclopedia of Reagents for Organic Synthesis. New York: J. Wiley & Sons. doi:10.1002/047084289X.rs052. ISBN   978-0471936237.
  10. ↑ Brown, H. C. "Organic Syntheses via Boranes" John Wiley & Sons, Inc. New York: 1975. ISBN   0-471-11280-1. page 260-261
  11. ↑ Lo, Chih-ting F.; Karan, Kunal; Davis, Boyd R. (2007). "Kinetic Studies of Reaction between Sodium Borohydride and Methanol, Water, and Their Mixtures". Industrial & Engineering Chemistry Research. 46 (17): 5478–5484. doi:10.1021/ie0608861.
  12. ↑ "Structural transitions in NaBH[sub 4] under pressure". Appl. Phys. Lett. 87 (26): 261916. 2005. doi:10.1063/1.2158505.
  13. ↑ Filinchuk, Y.; Talyzin, A. V.; Chernyshov, D.; Dmitriev, V. (2007). "High-pressure phase of NaBH4: Crystal structure from synchrotron powder diffraction data". Phys. Rev. B. 76 (9): 092104. Bibcode:2007PhRvB..76i2104F. doi:10.1103/PhysRevB.76.092104. S2CID   122588719.
  14. ↑ Kim, E.; Kumar, R.; Weck, P. F.; Cornelius, A. L.; Nicol, M.; Vogel, S. C.; Zhang, J.; Hartl, M.; Stowe, A. C.; Daemen, L.; Zhao, Y. (2007). "Pressure-driven phase transitions in NaBH4: theory and experiments". J. Phys. Chem. B. 111 (50): 13873–13876. doi:10.1021/jp709840w. PMID   18031032.
  15. 1 2 3 Wietelmann, Ulrich; Felderhoff, Michael; Rittmeyer, Peter (2002). "Hydrides". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA. doi:10.1002/14356007.a13_199.pub2. ISBN   978-3-527-30673-2. OCLC   751968805.
  16. ↑ Schubert, F.; Lang, K.; Burger, A. (1960) "Alkali metal borohydrides" (Bayer). German patent DE 1088930 19600915 (ChemAbs: 55:120851). Supplement to. to Ger. 1,067,005 (CA 55, 11778i). From the abstract: "Alkali metal borosilicates are treated with alkali metal hydrides in approx. 1:1 ratio at >100 °C with or without H pressure"
  17. ↑ Wu, Ying et al. (2004) Review of Chemical Processes for the Synthesis of Sodium Borohydride. Millennium Cell Inc.
  18. ↑ Ouyang, Liuzhang; Zhong, Hao; Li, Hai-Wen; Zhu, Min (2018). "A Recycling Hydrogen Supply System of NaBH4 Based on a Facile Regeneration Process: A Review". Inorganics. 6: 10. doi: 10.3390/inorganics6010010 .
  19. ↑ Banfi, Luca; Narisano, Enrica; Riva, Renata; Stiasni, Nikola; Hiersemann, Martin; Yamada, Tohru; Tsubo, Tatsuyuki (2014), "Sodium Borohydride", Encyclopedia of Reagents for Organic Synthesis, John Wiley & Sons, pp. 1–13, doi:10.1002/047084289x.rs052.pub3, ISBN   9780470842898
  20. ↑ Carey, Francis A. (2016-01-07). Organic chemistry. Giuliano, Robert M., 1954– (Tenth ed.). New York, NY. ISBN   9780073511214. OCLC   915135847.{{cite book}}: CS1 maint: location missing publisher (link)
  21. ↑ Loudon, Marc (2009). Organic chemistry (5th ed.). Greenwood Village, Colo.: Roberts and Co. ISBN   9780981519432. OCLC   263409353.
  22. ↑ Wigfield, Donald C.; Gowland, Frederick W. (March 1977). "The kinetic role of hydroxylic solvent in the reduction of ketones by sodium borohydride. New proposals for mechanism, transition state geometry, and a comment on the origin of stereoselectivity". The Journal of Organic Chemistry. 42 (6): 1108–1109. doi:10.1021/jo00426a048.
  23. ↑ Wigfield, Donald C. (January 1979). "Stereochemistry and mechanism of ketone reductions by hydride reagents". Tetrahedron. 35 (4): 449–462. doi:10.1016/0040-4020(79)80140-4. ISSN   0040-4020.
  24. ↑ da Costa, Jorge C.S.; Pais, Karla C.; Fernandes, Elisa L.; de Oliveira, Pedro S. M.; Mendonça, Jorge S.; de Souza, Marcus V. N.; Peralta, Mônica A.; Vasconcelos, Thatyana R.A. (2006). "Simple reduction of ethyl, isopropyl and benzyl aromatic esters to alcohols using sodium borohydride-methanol system" (PDF). Arkivoc : 128–133. Retrieved 29 August 2006.
  25. ↑ Dalla, V.; Catteau, J.P.; Pale, P. (1999). "Mechanistic rationale for the NaBH4 reduction of α-keto esters". Tetrahedron Letters. 40 (28): 5193–5196. doi:10.1016/S0040-4039(99)01006-0.
  26. ↑ Periasamy, Mariappan; Thirumalaikumar, Muniappan (2000). "Methods of enhancement of reactivity and selectivity of sodium borohydride for applications in organic synthesis". Journal of Organometallic Chemistry. 609 (1–2): 137–151. doi:10.1016/S0022-328X(00)00210-2.
  27. ↑ Nora de Souza, Marcus Vinícius; Alves Vasconcelos; Thatyana Rocha (1 November 2006). "Recent methodologies mediated by sodium borohydride in the reduction of different classes of compounds". Applied Organometallic Chemistry. 20 (11): 798–810. doi:10.1002/aoc.1137.
  28. ↑ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, ISBN   978-0-471-72091-1
  29. ↑ Brown, Jack D.; Haddenham, Dustin (2013). "Sodium Borohydride and Iodine". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn01598. ISBN   978-0471936237.
  30. ↑ Ryschlewitsch, G. E.; Nainan, K. C. (1974). "Octahydrotriborate (1-) ([B 3 H 8]) salts". Inorganic Syntheses. Vol. 15. pp. 111–118. doi:10.1002/9780470132463.ch25. ISBN   9780470132463.
  31. ↑ Lucas, C. R. (1977). "Bis(η 5 -Cyclopentadienyl) [Tetrahydroborato(1−)]Titanium". Inorganic Syntheses. Vol. 17. p. 93. doi:10.1002/9780470132487.ch27. ISBN   9780470132487.
  32. ↑ Istek, A. and Gonteki, E. (2009). "Utilization of sodium borohydride (NaBH4) in kraft pulping process" (PDF). Journal of Environmental Biology. 30 (6): 951–953. PMID   20329388.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  33. ↑ Eun Hee Park, Seong Uk Jeong, Un Ho Jung, Sung Hyun Kim, Jaeyoung Lee, Suk Woo Nam, Tae Hoon Lim, Young Jun Park, Yong Ho Yuc (2007): "Recycling of sodium metaborate to borax". International Journal of Hydrogen Energy, volume 32, issue 14, pages 2982-2987. doi : 10.1016/j.ijhydene.2007.03.029
  34. ↑ Z. P. Li, B. H. Liu. K. Arai, N. Morigazaki, S. Suda (2003): "Protide compounds in hydrogen storage systems". Journal of Alloys and Compounds, volumes 356–357, pages 469-474. doi : 10.1016/S0925-8388(02)01241-0
  35. ↑ Hasan K. Atiyeh and Boyd R. Davis (2007): "Separation of sodium metaborate from sodium borohydride using nanofiltration membranes for hydrogen storage application". International Journal of Hydrogen Energy, volume 32, issue 2, pages 229-236. doi : 10.1016/j.ijhydene.2006.06.003
  36. ↑ Stuart Gary, "Hydrogen storage no longer up in the air" in ABC Science 16 August 2012, citing Christian, Meganne; Aguey-Zinsou, Kondo François (2012). "Core–Shell Strategy Leading to High Reversible Hydrogen Storage Capacity for NaBH4". ACS Nano . 6 (9): 7739–7751. doi:10.1021/nn3030018. PMID   22873406.
  37. ↑ Masters, Kristin. "How to Prevent and Reverse Foxing in Rare Books". bookstellyouwhy.com. Retrieved 3 April 2018.
  38. ↑ Seyden-Penne, J. (1991) Reductions by the Alumino- and Borohydrides in Organic Synthesis. VCH–Lavoisier: Paris. p. 9. ISBN   978-0-471-19036-3
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