Benzene boronic acid

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Structural formula
Structural formula of benzene boronic acid
General
Surname Benzene boronic acid
other names
  • Dihydroxy (phenyl) borane
  • Phenylboronic acid
Molecular formula C 6 H 7 BO 2
Brief description

colorless to yellowish odorless solid

External identifiers / databases
CAS number 98-80-6
EC number 202-701-9
ECHA InfoCard 100.002.456
PubChem 66827
ChemSpider 60191
DrugBank DB01795
Wikidata Q408739
properties
Molar mass 121.93 g mol −1
Physical state

firmly

Melting point

217–220 ° C (anhydrate)

pK s value

8.83

solubility

soluble in water (10 g l −1 at 20 ° C)

safety instructions
GHS labeling of hazardous substances
07 - Warning

Caution

H and P phrases H: 302
P: no P-phrases
Toxicological data

740 mg kg −1 ( LD 50ratoral )

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 . Template: room group / 45

Triphenyl boroxine synthesis01.svg

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

  1. a b c d e data sheet Phenylboronic acid, purum, 97.0% (HPLC) from Sigma-Aldrich , accessed on May 19, 2017 ( PDF ).
  2. a b c data sheet benzene boronic acid (PDF) from Merck , accessed on August 13, 2011.
  3. Entry on phenylboronic acid. In: Römpp Online . Georg Thieme Verlag, accessed on April 17, 2014.
  4. 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.
  5. ^ 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 ).
  6. 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 .
  7. 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 .
  8. 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 .
  9. 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 .