Borane–tetrahydrofuran

Borane–tetrahydrofuran is a dipolar bond charge-transfer complex composed of borane and tetrahydrofuran (THF). These solutions are used for reductions and hydroboration, reactions that are useful in synthesis of organic compounds.[1]

Borane–tetrahydrofuran
Identifiers
3D model (JSmol)
ECHA InfoCard 100.034.424
EC Number
  • 237-881-8
UNII
Properties
C4H11BO
Molar mass 85.94 g·mol−1
Appearance White solid
Melting point 66 °C (151 °F; 339 K)
Hazards
GHS pictograms
GHS Signal word Danger
H225, H260, H302, H315, H318, H319, H335
P210, P223, P231+232, P233, P240, P241, P242, P243, P261, P264, P270, P271, P280, P301+312, P302+352, P303+361+353, P304+340, P305+351+338, P310, P312, P321, P330, P332+313, P335+334, P337+313
Flash point −17 °C (1 °F; 256 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Preparation and uses

The complex is commercially available but can also be generated by the dissolution of diborane in THF. A practical route to this is the oxidation of sodium borohydride with iodine in THF.[2]

The complex can reduce carboxylic acids to alcohols and is a common route for the reduction of amino acids to amino alcohols[3] (e.g. valinol). It adds across alkenes to give organoboron compounds that are useful intermediates.[4] The following organoboron reagents are prepared from borane-THF: 9-borabicyclo[3.3.1]nonane, Alpine borane, diisopinocampheylborane. It is also used as a source of borane (BH3) for the formation of adducts.[5]

Safety

The solution is highly sensitive to air, requiring the use of air-free techniques.[1]

See also

References
  1. Marek Zaidlewicz, Herbert C. Brown, Santhosh F. Neelamkavil, "Borane–Tetrahydrofuran" Encyclopedia of Reagents for Organic Synthesis, 2008 John Wiley & Sons. doi:10.1002/047084289X.rb241.pub2
  2. Kanth, J. V. Bhaskar; Periasamy, Mariappan (1 September 1991). "Selective reduction of carboxylic acids into alcohols using sodium borohydride and iodine". The Journal of Organic Chemistry. 56 (20): 5964–5965. doi:10.1021/jo00020a052.
  3. McKennon, Marc J.; Meyers, A. I.; Drauz, Karlheinz; Schwarm, Michael (June 1993). "A convenient reduction of amino acids and their derivatives". The Journal of Organic Chemistry. 58 (13): 3568–3571. doi:10.1021/jo00065a020.
  4. Kabalka, George W.; Maddox, John T.; Shoup, Timothy; Bowers, Karla R. (1996). "A Simple And Convenient Method For The Oxidation Of Organoboranes Using Sodium Perborate: (+)-isopinocampheol". Organic Syntheses. 73: 116.
  5. Crépy, Karen V. L.; Imamoto, Tsuneo (2005). "Preparation Of (S,S)-1,2-Bis-(tert-butylmethylphosphino)ethane ((S,S)-t-Bu-BISP*) As A Rhodium Complex". Organic Syntheses. 82: 22.
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