New Jobs:

- Sr Scientist (Ionis)

- Sr Scientist (AbbVie)

- Postdoc (Los Alamos)

- Research Chemist (Optima)

Latest Internships:

- USC

  (Summer 2018)

- Kansas State

  (Summer 2018)



Sodium Borohydride


Other Names:

Sodium tetrahydridoborate

Sodium tetrahydroborate






General Information:


Structure:



CAS Number: 16940-66-2

Molecular Weight: 37.83 g/mol

Appearance: White solid


Sodium borohydride (NaBH4) is a mild reducing agent that is typically used to reduce aldehydes and ketones to their respective alcohols. NaBH4 is sometimes used to reduce esters to alcohols but the reaction is generally slow. This difference in reactivity usually allows for the selective reduction of aldehydes and ketones in the presence of esters. Carboxylic acids, nitriles, and amides are not reduced by NaBH4 under normal conditions. However, carboxylic acids can be reduced by NaBH4 if they have been activated by an appropriate activating agent. NaBH4 is also occasionally used for reductive aminations.


NaBH4 is usually used in hydroxylic solvents such as MeOH, EtOH, and H2O. Sometimes THF is used as a solvent, either alone or as a solvent mixture (ex. THF/MeOH or THF/EtOH). In MeOH and EtOH, NaBH4 decomposes over time to give the respective borates. An excess of NaBH4 can be used to compensate for the decomposition of the reagent over time.




Common Uses:


Reagent for the reduction of aldehydes to alcohols





Reagent for the reduction of ketones to alcohols





Reagent for the reduction of esters to alcohols





Reagent for the reduction of activated carboxylic acid derivatives to alcohols





Reagent for reductive amination





Safety:


Sodium borohydride (NaBH4) decomposes rapidly in water (especially if acidic). The reaction is exothermic and produces diborane gas (toxic), hydrogen gas (flammable), and boric acid (weak acid).




References:


1) WO2016014463, page 99

2) WO2011017578, page 127

3) WO2015051043, page 85

4) WO2015158653, page 35

5) WO2015129926, page 74

6) Burke, S. D.; Danheiser, R. L.; Handbook of Reagents for Organic Synthesis, Oxidizing and Reducing Agents

7) Carey, F. A.; Sundberg, R. J.; Advanced Organic Chemistry, Part B: Reactions and Synthesis, 5th Edition

8) Wikipedia: Sodium borohydride (link)

9) www.sigmaaldrich.com: Sodium borohydride (link)




Related Books: