2-Thiopheneboronic acid Chemical Properties

Melting point:

138-140 °C (lit.)

Boiling point:

287.9±32.0 °C(Predicted)

Density 

1.32±0.1 g/cm3(Predicted)

storage temp. 

2-8°C

solubility 

Soluble in methanol.

pka

8.41±0.53(Predicted)

form 

Powder

color 

Off-white to beige

BRN 

112375

Stability:

store cold

InChI

InChI=1S/C4H5BO2S/c6-5(7)4-2-1-3-8-4/h1-3,6-7H

InChIKey

ARYHTUPFQTUBBG-UHFFFAOYSA-N

SMILES

C1(B(O)O)SC=CC=1

CAS DataBase Reference

6165-68-0(CAS DataBase Reference)

Safety Information

Hazard Codes 

Xn,Xi

Risk Statements 

22-36/37/38

Safety Statements 

26-36/37-37/39-36

WGK Germany 

3

Hazard Note 

Harmful/Irritant/Keep Cold

HazardClass 

IRRITANT, IRRITANT-HARMFUL, KEEP COLD

HS Code 

29339900

MSDS

• Language:English Provider:SigmaAldrich
• Language:English Provider:ACROS
• Language:English Provider:ALFA

2-Thiopheneboronic acid Usage And Synthesis

Chemical Properties

white to light yellow crystal powder

Uses

suzuki reaction

Uses

2-Thienylboronic Acid is a reagent used for palladium-catalyzed Suzuki-Miyaura cross-couplings. It is also used in preparation of photophysical properties of oxygen-containing polycyclic aromatic triptycenes.

Uses

2-Thiopheneboronic acid can be used as reagent used for Palladium-catalyzed Suzuki-Miyaura cross-couplings; Alkylation, boration, coupling reaction, Suzuki coupling, and halogenation of fluorenyl bromide ;Chain-growth catalyst transfer polycondensation of conjugated alternating copolymer; Ferric perchlorate-promoted reaction of fullerene to give fullerenyl boronic esters.

Synthesis

General procedure for the synthesis of 2-thiophene boronic acid from 2-bromothiophene: Triphenylphosphine (0.131 g, 0.5 mmol, 20 mol%), p-iodoanisole (0.585 g, 2.5 mmol), and triethylamine (1.78 mL, 12.5 mmol) were added sequentially to a 50 mL round-bottomed flask (equipped with a side arm, condenser, and stirring bar). The reaction system was degassed three times by alternating vacuum and argon displacement. Palladium dichloride (0.023 g, 0.13 mmol, 5 mol%) was added under positive argon pressure. After stirring at room temperature for 15 minutes, diisopropylaminoborane (5 mL, 1 M THF solution, 5 mmol) was added and again degassed three times by alternating vacuum and argon displacement. The reaction mixture was heated to reflux and kept at reflux for 12 hours. Upon completion of the reaction, the mixture was cooled to 0°C and 6 mL of methanol was slowly added (note: this process is exothermic and accompanied by hydrogen release). After stirring for 15 minutes, all solvent was removed by distillation under reduced pressure to give a black solid. The solid was dissolved with 3M sodium hydroxide solution (8 mL) and subsequently washed with hexane (3 x 10 mL). The aqueous layer was cooled to 0°C (ice bath) and acidified with concentrated hydrochloric acid to pH ≤ 1, at which point 2-thiopheneboronic acid precipitated as a white solid. The aqueous layer was extracted with ether (3 x 10 mL), the organic phases were combined, dried with magnesium sulfate and filtered. Finally, the solvent was removed by distillation under reduced pressure to obtain 2-thiopheneboronic acid as a white solid.

References

[1] Tetrahedron, 2011, vol. 67, # 3, p. 576 - 583
[2] Arkiv foer Kemi, 1957, vol. 11, p. 373,379, 380
[3] New Journal of Chemistry, 2002, vol. 26, # 4, p. 373 - 375
[4] Patent: EP674635, 2001, B1

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