Summary
Bis(pinacolato)diboron is a covalent compound containing two boron atoms and two pinacolato ligands. It has the formula [(CH3)4C2O2B]2; the pinacol groups are sometimes abbreviated as "pin", so the structure is sometimes represented as B2pin2. It is a colourless solid that is soluble in organic solvents. It is a commercially available reagent for making pinacol boronic esters for organic synthesis. Unlike some other diboron compounds, B2pin2 is not moisture-sensitive and can be handled in air.[1]
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| Preferred IUPAC name
Octamethyl-2,2′-bi-1,3,2-dioxaborolane | |
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3D model (JSmol)
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| Abbreviations | B2pin2 |
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| ECHA InfoCard | 100.111.245 |
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| C12H24B2O4 | |
| Molar mass | 253.94 g·mol−1 |
| Melting point | 137 to 140 °C (279 to 284 °F; 410 to 413 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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Preparation and structure edit
This compound may be prepared by treating tetrakis(dimethylamino)diboron with pinacol in acidic conditions.[1] The B-B bond length is 1.711(6) Å.
Dehydrogenation of pinacolborane provides an alternative route:[2]
- 2 (CH3)4C2O2BH → (CH3)4C2O2B-BO2C2(CH3)4 + H2
Reactions edit
The B-B bond adds across alkenes and alkynes to give the 1,2-diborylated alkanes and alkenes. Using various organorhodium or organoiridium catalysts, it can also be installed onto saturated hydrocarbons:[3]
- CH3(CH2)6CH3 + [pinB]2 → pinBH + CH3(CH2)7Bpin
These reactions proceed via boryl complexes. Bis(pinacolato)diboron can also be used as reducing agent for example in transition metal catalyzed hydrogenations of alkenes and alkynes. [4]
References edit
- ^ a b Tatsuo Ishiyama; Miki Murata; Taka-aki Ahiko & Norio Miyaura (2004). "Bis(pinacolato)diboron". Organic Syntheses; Collected Volumes, vol. 10, p. 115.
- ^ Neeve, Emily C.; Geier, Stephen J.; Mkhalid, Ibraheem A. I.; Westcott, Stephen A.; Marder, Todd B. (2016). "Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse". Chemical Reviews. 116 (16): 9091–9161. doi:10.1021/acs.chemrev.6b00193. hdl:1807/78811. PMID 27434758.
- ^ Xinyu Liu "Bis(pinacolato)diboron" Synlett 2003, pp 2442–2443. doi:10.1055/s-2003-43344
- ^ "Bis(pinacolato)diboron, B2pin2".