Pinacolborane

Pinacolborane is the borane with the formula (CH₃)₄C₂O₂BH. Often pinacolborane is abbreviated HBpin.^[1] It features a boron hydride functional group incorporated in a five-membered C₂O₂B ring. Like related boron alkoxides, pinacolborane is monomeric. It is a colorless liquid.^[2] It features a reactive B-H functional group.^[3]

Pinacolborane

Names
Preferred IUPAC name 4,4,5,5-Tetramethyl-1,3,2-dioxaborolane
Other names HBpin
Identifiers
CAS Number	25015-63-8
3D model (JSmol)	Interactive image
ChemSpider	2016512
ECHA InfoCard	100.118.700
EC Number	607-485-3
PubChem CID	6364989
CompTox Dashboard (EPA)	DTXSID30422852
InChI InChI=1S/C6H12BO2/c1-5(2)6(3,4)9-7-8-5/h1-4H3 Key: LZPWAYBEOJRFAX-UHFFFAOYSA-N
SMILES [B]1OC(C(O1)(C)C)(C)C
Properties
Chemical formula	C6H13BO2
Molar mass	127.98 g·mol−1
Appearance	colorless liquid
Density	0.882 g/cm3
Boiling point	42–43 °C (108–109 °F; 315–316 K) 50 mmHg
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H220, H225, H260, H261, H315, H318
Precautionary statements	P210, P223, P231+P232, P233, P240, P241, P242, P243, P264, P280, P302+P352, P303+P361+P353, P305+P351+P338, P310, P321, P332+P313, P335+P334, P362, P370+P378, P377, P381, P402+P404, P403, P403+P235, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Use in organic synthesis

In the presence of catalysts, pinacolborane hydroborates alkenes and, less rapidly, alkynes.^[3][4]

Pinacolborane also affects catalyst-free hydroboration of aldehydes,^[5] ketones,^[6] and carboxylic acids.^[7]

Pinacolborane is used in borylation, a form of C-H activation.^[8][9]

Dehydrogenation of pinacolborane affords dipinacolatodiborane (B₂pin₂):^[10]

2 (CH₃)₄C₂O₂BH → (CH₃)₄C₂O₂B-BO₂C₂(CH₃)₄ + H₂

Related compounds

• Catecholborane