Benzene boronic acid
Structural formula | ||||||||||||||||||||||
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General | ||||||||||||||||||||||
Surname | Benzene boronic acid | |||||||||||||||||||||
other names |
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Molecular formula | C 6 H 7 BO 2 | |||||||||||||||||||||
Brief description |
colorless to yellowish odorless solid |
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properties | ||||||||||||||||||||||
Molar mass | 121.93 g mol −1 | |||||||||||||||||||||
Physical state |
firmly |
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Melting point |
217–220 ° C (anhydrate) |
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pK s value |
8.83 |
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solubility |
soluble in water (10 g l −1 at 20 ° C) |
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safety instructions | ||||||||||||||||||||||
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Toxicological data | ||||||||||||||||||||||
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Benzene boronic acid , also known as phenyl boronic acid , is a chemical compound from the group of organoboronic acids .
Extraction and presentation
There are numerous methods to synthesize benzene boronic acid. A common synthesis uses phenylmagnesium bromide and trimethyl borate to form the corresponding ester , which is then converted to phenylboronic acid by hydrolysis .
- PhMgBr + B (OMe) 3 → PhB (OMe) 2 + MeOMgBr
- PhB (OMe) 2 + H 2 O → PhB (OH) 2 + MeOH
An analogous synthesis can also be carried out starting from phenyllithium .
- PhLi + B (OMe) 3 → PhB (OMe) 2 + MeOLi
- PhB (OMe) 2 + H 2 O → PhB (OH) 2 + MeOH
properties
Benzene boronic acid is a colorless to yellowish odorless solid. The solid forms an orthorhombic crystal lattice with space group Iba 2 (space group no. 45) . Dimers are present in the solid. The compound can be trimerized to the anhydrate triphenylboroxine by means of dry heating with elimination of water . The reaction proceeds endothermically from the solid phase with a heat of reaction of 41 kJ mol −1 .
use
Benzene boronic acid is used in numerous cross-coupling reactions. In 1979 Miyarura and Suzuki found a carbon-carbon bond formation reaction (now known as Suzuki coupling ) which convert aryl boronic acids with halogenated aromatics using palladium-phosphine complexes to form biphenyl derivatives or vinyl aromatics.
Individual evidence
- ↑ a b c d e data sheet Phenylboronic acid, purum, 97.0% (HPLC) from Sigma-Aldrich , accessed on May 19, 2017 ( PDF ).
- ↑ a b c data sheet benzene boronic acid (PDF) from Merck , accessed on August 13, 2011.
- ↑ Entry on phenylboronic acid. In: Römpp Online . Georg Thieme Verlag, accessed on April 17, 2014.
- ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Dissociation Constants of Organic Acids and Bases, pp. 8-45.
- ^ A b Robert M. Washburn, Ernest Levens, Charles F. Albright, Franklin A. Cheap: Benzeneboronic Anhydride In: Organic Syntheses . 39, 1959, p. 3, doi : 10.15227 / orgsyn.039.0003 ; Coll. Vol. 4, 1963, p. 68 ( PDF ).
- ↑ Cundy, DJ; Forsyth, SA: Cupric acetate mediated N-arylation by arylboronic acids: A preliminary investigation into the scope of application in Tetrahedron Letters 39 (1998) 7979-7982, doi : 10.1016 / S0040-4039 (98) 01735-3 .
- ↑ a b Rettig, SJ; Trotter, J .: Crystal and molecular structure of phenylboronic acid, C 6 H 5 B (OH) 2 in Can. J. Chem. 55 (1977) 3071-3075, doi : 10.1139 / v77-430 , pdf .
- ↑ a b Finch, A .; Gardner, PJ: Thermochemistry of phenylboronic acid, diphenylborinic acid, and their anhydrides in Trans. Faraday Soc. 62 (1966) 3314-3318, doi : 10.1039 / TF9666203314 .
- ↑ Miyaura, N .; Suzuki, A .: Stereoselective synthesis of arylated (E) -alkenes by the reaction of alk-1-enylboranes with aryl halides in the presence of palladium catalyst . In: J. Chem. Soc., Chem. Commun. . No. 19, 1979, p. 866. doi : 10.1039 / C39790000866 .