Bis(pinacolato)diboron

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Bis(pinacolato)diboron
Bpin2.svg
Bis(pinacolato)diboron-from-xtal-1984-3D-balls-web.png
Names
Preferred IUPAC name
Octamethyl-2,2′-bi-1,3,2-dioxaborolane
Identifiers
3D model (JSmol)
AbbreviationsB2pin2
ChEBI
ChemSpider
ECHA InfoCard 100.111.245 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C12H24B2O4/c1-9(2)10(3,4)16-13(15-9)14-17-11(5,6)12(7,8)18-14/h1-8H3 X mark.svgN
    Key: IPWKHHSGDUIRAH-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C12H24B2O4/c1-9(2)10(3,4)16-13(15-9)14-17-11(5,6)12(7,8)18-14/h1-8H3
    Key: IPWKHHSGDUIRAH-UHFFFAOYAV
  • B1(OC(C(O1)(C)C)(C)C)B2OC(C(O2)(C)C)(C)C
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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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]

Contents

Preparation and structure

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

Pinacolborane is a closely related reagent. Pinacolborane.svg
Pinacolborane is a closely related reagent.

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]

Related Research Articles

<span class="mw-page-title-main">Alkene</span> Hydrocarbon compound containing one or more C=C bonds

In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.

<span class="mw-page-title-main">Alkyne</span> Hydrocarbon compound containing one or more C≡C bonds

In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula CnH2n−2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature. Like other hydrocarbons, alkynes are generally hydrophobic.

<span class="mw-page-title-main">Ester</span> Compound derived from an acid

In chemistry, an ester is a compound derived from an acid in which the hydrogen atom (H) of at least one acidic hydroxyl group of that acid is replaced by an organyl group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well, but not according to the IUPAC.

<span class="mw-page-title-main">Ketone</span> Organic compounds of the form >C=O

In organic chemistry, a ketone is an organic compound with the structure R−C(=O)−R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group −C(=O)−. The simplest ketone is acetone, with the formula (CH3)2CO. Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids, and the solvent acetone.

A diol is a chemical compound containing two hydroxyl groups. An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified.

Cyclopropene is an organic compound with the formula C3H4. It is the simplest cycloalkene. Because the ring is highly strained, cyclopropene is difficult to prepare and highly reactive. This colorless gas has been the subject for many fundamental studies of bonding and reactivity. It does not occur naturally, but derivatives are known in some fatty acids. Derivatives of cyclopropene are used commercially to control ripening of some fruit.

In organic chemistry, ozonolysis is an organic reaction where the unsaturated bonds are cleaved with ozone. Multiple carbon–carbon bond are replaced by carbonyl groups, such as aldehydes, ketones, and carboxylic acids. The reaction is predominantly applied to alkenes, but alkynes and azo compounds are also susceptible to cleavage. The outcome of the reaction depends on the type of multiple bond being oxidized and the work-up conditions.

<span class="mw-page-title-main">Organoboron chemistry</span> Study of compounds containing a boron-carbon bond

Organoboron chemistry or organoborane chemistry studies organoboron compounds, also called organoboranes. These chemical compounds combine boron and carbon; typically, they are organic derivatives of borane (BH3), as in the trialkyl boranes.

In organic chemistry, hydroboration refers to the addition of a hydrogen-boron bond to certain double and triple bonds involving carbon. This chemical reaction is useful in the organic synthesis of organic compounds.

Boron trichloride is the inorganic compound with the formula BCl3. This colorless gas is a reagent in organic synthesis. It is highly reactive toward water.

<span class="mw-page-title-main">Boronic acid</span> Organic compound of the form R–B(OH)2

A boronic acid is an organic compound related to boric acid in which one of the three hydroxyl groups is replaced by an alkyl or aryl group. As a compound containing a carbon–boron bond, members of this class thus belong to the larger class of organoboranes.

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

Pinacol is a white solid organic compound. It is a diol that has hydroxyl groups (-OH) on vicinal carbon atoms.

Hydrosilylation, also called catalytic hydrosilation, describes the addition of Si-H bonds across unsaturated bonds. Ordinarily the reaction is conducted catalytically and usually the substrates are unsaturated organic compounds. Alkenes and alkynes give alkyl and vinyl silanes; aldehydes and ketones give silyl ethers. Hydrosilylation has been called the "most important application of platinum in homogeneous catalysis."

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

Organoaluminium chemistry is the study of compounds containing bonds between carbon and aluminium. It is one of the major themes within organometallic chemistry. Illustrative organoaluminium compounds are the dimer trimethylaluminium, the monomer triisobutylaluminium, and the titanium-aluminium compound called Tebbe's reagent. The behavior of organoaluminium compounds can be understood in terms of the polarity of the C−Al bond and the high Lewis acidity of the three-coordinated species. Industrially, these compounds are mainly used for the production of polyolefins.

In chemistry, carbonylation refers to reactions that introduce carbon monoxide (CO) into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbonylation also refers to oxidation of protein side chains.

Metal-catalyzed C–H borylation reactions are transition metal catalyzed organic reactions that produce an organoboron compound through functionalization of aliphatic and aromatic C–H bonds and are therefore useful reactions for carbon–hydrogen bond activation. Metal-catalyzed C–H borylation reactions utilize transition metals to directly convert a C–H bond into a C–B bond. This route can be advantageous compared to traditional borylation reactions by making use of cheap and abundant hydrocarbon starting material, limiting prefunctionalized organic compounds, reducing toxic byproducts, and streamlining the synthesis of biologically important molecules. Boronic acids, and boronic esters are common boryl groups incorporated into organic molecules through borylation reactions. Boronic acids are trivalent boron-containing organic compounds that possess one alkyl substituent and two hydroxyl groups. Similarly, boronic esters possess one alkyl substituent and two ester groups. Boronic acids and esters are classified depending on the type of carbon group (R) directly bonded to boron, for example alkyl-, alkenyl-, alkynyl-, and aryl-boronic esters. The most common type of starting materials that incorporate boronic esters into organic compounds for transition metal catalyzed borylation reactions have the general formula (RO)2B-B(OR)2. For example, bis(pinacolato)diboron (B2Pin2), and bis(catecholato)diborane (B2Cat2) are common boron sources of this general formula.

Organoniobium chemistry is the chemistry of compounds containing niobium-carbon (Nb-C) bonds. Compared to the other group 5 transition metal organometallics, the chemistry of organoniobium compounds most closely resembles that of organotantalum compounds. Organoniobium compounds of oxidation states +5, +4, +3, +2, +1, 0, -1, and -3 have been prepared, with the +5 oxidation state being the most common.

Miyaura borylation, also known as the Miyaura borylation reaction, is a named reaction in organic chemistry that allows for the generation of boronates from vinyl or aryl halides with the cross-coupling of bis(pinacolato)diboron in basic conditions with a catalyst such as PdCl2(dppf). The resulting borylated products can be used as coupling partners for the Suzuki reaction.

Norio Miyaura was a Japanese organic chemist. He was a professor of graduate chemical engineering at Hokkaido University. His major accomplishments surrounded his work in cross-coupling reactions / conjugate addition reactions of organoboronic acids and addition / coupling reactions of diborons and boranes. He is also the co-author of Cross-Coupling Reactions: A Practical Guide with M. Nomura E. S.. Miyaura was a world-known and accomplished researcher by the time he retired and so, in 2007, he won the Japan Chemical Society Award.

<span class="mw-page-title-main">Tetrahalodiboranes</span> Class of diboron compounds

Tetrahalodiboranes are a class of diboron compounds with the formula . These compounds were first discovered in the 1920s, but, after some interest in the middle of the 20th century, were largely ignored in research. Compared to other diboron compounds, tetrahalodiboranes are fairly unstable and historically have been difficult to prepare; thus, their use in synthetic chemistry is largely unexplored, and research on tetrahalodiboranes has stemmed from fundamental interest in their reactivity. Recently, there has been a resurgence in interest in tetrahalodiboranes, particularly in diboron tetrafluoride as a reagent to promote doping of silicon with for use in semiconductor devices.

References

  1. 1 2 Tatsuo Ishiyama; Miki Murata; Taka-aki Ahiko & Norio Miyaura (2004). "Bis(pinacolato)diboron". Organic Syntheses .; Collective Volume, vol. 10, p. 115
  2. 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.
  3. Xinyu Liu "Bis(pinacolato)diboron" Synlett 2003, pp 2442–2443. doi : 10.1055/s-2003-43344
  4. "Bis(pinacolato)diboron, B2pin2".