Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound with the formula NaBH4. The solid is known to exist as three polymorphs: α, β and γ. The density of sodium borohydride at STP corresponds to 1.07 grams per cubic centimetre. The literature value of the benzopinacolone is 182-184 C in which the large difference of melting point tells us the large mount of impurities that have occurred during the process. This white solid, usually encountered as a powder, is a versatile reducing agent that finds wide application in chemistry, both in the laboratory and on a … (1960) "Alkali metal borohydrides" (Bayer). The melting point of the vanillyl alcohol produced was 97°C as compared to the actual melting point of vanillyl alcohol at 115°C. The molar mass of this compound is 37.83 g/mol, and the melting point is 400◦C. 4). Sodium borohydride. Boiling Point: 500ºC: Melting Point: 400ºC (dec.) Molecular Formula: H 4 BNa: Molecular Weight: 37.833: Flash Point: 69ºC: Exact Mass: 38.030376: Vapour Pressure: 86.91mmHg at 25°C: Stability: Stability Stable, but reacts readily with water (reaction may be violent). α,β-Unsaturated esters also undergo 1,4-reduction in the presence of NaBH4. Sodium Borohydride is generally immediately available in most volumes. These usually involve replacing hydride with alkyl groups, such as lithium triethylborohydride and L-selectride (lithium tri-sec-butylborohydride), or replacing B with Al. [27] The combination of NaBH4 with carboxylic acids results in the formation of acyloxyborohydride species, such as STAB. In redox reactions, the reductant (or reducing agent) loses electrons and is oxidized while the oxidant (or oxidizing agent) gains electrons and is reduced. Physical Properties of Sodium Borohydride. [BH4-]. The overall percent yield of this series of reactions was calculated to be 44.45%, while the percent yield for the formation of the hydrobenzoin was calculated to be 60.62%. Prelab Questions. Developing Chamber: Ethyl Acetate = 4mL Benzoin Solution = <10mg Benzoin Product + 1-2mL Acetone Plate #1 – RXN @ 15min Distance Travelled Solvent = 4.6cm Distance Travelled RXN Mixture @ 15min = 0.2cm Distance Travelled Benzoin Solution = 1.0cm Rf (RXN Mixture @ 15min) = 0.043478 Rf (Benzoin Solution) = 0.2173913 Sodium borohydride Reduction of Benzil Introduction: The Purpose of this experiment is for the students to learn how to use sodium borohydride to reduce benzil to its secondary alcohol product via reduction reaction. [23][24] Oxidation with iodine in tetrahydrofuran gives the borane–tetrahydrofuran complex, which can reduce carboxylic acids. Such borohydride complexes are often prepared by the action of NaBH4 (or the LiBH4) on the corresponding metal halide. NaBH. white (1) Other (1) Feature. The reducing agent transfers electrons to another substance. [7][8] Results of this wartime research were declassified and published in 1953. [9] Sodium borohydride is soluble in protic solvents such as water and lower alcohols. Although there was an abundance of product recovered and the crystals look really pure, the melting point of 169.3-171.2 disproves the purity. Synonym: Sodium tetrahydridoborate CAS Number: 16940-66-2. Melting point: 49 °C; Density: 1.0976 at 50 °C/50 °C (alpha-Benzophenone) Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. Two mini capillaries, containing the product only, were used to determine the product’s melting point. Articles of amberlyst(r) 15 are included as well. It also reacts with these protic solvents to produce H2; however, these reactions are fairly slow. heated NaNH 2 to 420 °C and found that NaNH 2 decomposes in two stages. Brown, H. C. “Organic Syntheses via Boranes” John Wiley & Sons, Inc. New York: 1975. The heat of this reaction may be sufficient to ignite the hydrogen. Sodium borohydride is a white to grayish crystalline powder. Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound with the formula NaBH4. [4][5] The compound is soluble in alcohols, certain ethers, and water, although it slowly hydrolyzes.[6]. Boiling point: 500 °C (vacuum); melting point: 400 °C; soluble in water and lower alcohols, ammonia, insoluble in ether, benzene, hydrocarbons; relative density (water = 1): 1.07; Sodium borohydride is usually used as reducing agent in synthesis of inorganic and organic synthesis. The electron donors can also form charge transfer complexes with electron acceptors. [19] Hydrogen-bonding activation is required, as no reduction occurs in an aprotic solvent like diglyme. It is decomposed by water to form sodium hydroxide, a corrosive material, and hydrogen, a flammable gas.The heat of this reaction may be sufficient to ignite the hydrogen.The material itself is easily ignited and burns vigorously once ignited. Nevertheless, an alcohol, often methanol or ethanol, is generally the solvent of choice for sodium borohydride reductions of ketones and aldehydes. The compound is soluble in alcohols, certain ethers, and water, although it slowly hydrolyzes. Sodium borohydride is an odorless white to gray-white microcrystalline powder that often forms lumps. The melting point of NaNH 2 is 210 °C and the boiling point is 405 °C. The narrower the range the more pure the compound is and the wider the range the less the purity of a compound. Freezing/Melting Point:decomposes Decomposition Temperature:> 305 deg C Solubility: 35% Specific Gravity/Density:1.07 Molecular Formula:H4BNa Molecular Weight:37.82 Section 10 - Stability and Reactivity Chemical Stability: Stable. Molecular Weight: 37.83 . The molar mass of NaBH 4 is 37.83 grams per mole. mol −1 : Appearance yellow crystalline powder Density: 1.23 g/cm 3, solid (1.255 g/cm 3, x-ray) : Melting point: 94.0 to 96.0 °C; 201.2 to 204.8 °F; 367.1 to 369.2 K It has been tested as pretreatment for pulping of wood, but is too costly to be commercialized. Exploiting this reactivity, sodium borohydride is used in prototypes of the direct borohydride fuel cell. [20][21], α,β-Unsaturated ketones tend to be reduced by NaBH4 in a 1,4-sense, although mixtures are often formed. Review: OP 12 – Vacuum filtration OP 28 – Melting point (using Mel-Temp®) Procedure Notes Calculate the necessary mass of vanillin and …

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