2-HYDROXY-5-METHYLPHENYLBORONIC ACID

2-HYDROXY-5-METHYLPHENYLBORONIC ACID Property

Boiling point:

343.7±52.0 °C(Predicted)

Density 

1.26±0.1 g/cm3(Predicted)

storage temp. 

Inert atmosphere,Store in freezer, under -20°C

pka

8.71±0.58(Predicted)

Appearance

White to off-white Solid

Safety

HS Code 

2931900090

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H315Causes skin irritation

H319Causes serious eye irritation

H335May cause respiratory irritation

Precautionary statements

P264Wash hands thoroughly after handling.

P264Wash skin thouroughly after handling.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P302+P352IF ON SKIN: wash with plenty of soap and water.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

P321Specific treatment (see … on this label).

P332+P313IF SKIN irritation occurs: Get medical advice/attention.

P362Take off contaminated clothing and wash before reuse.

2-HYDROXY-5-METHYLPHENYLBORONIC ACID Chemical Properties,Usage,Production

Synthesis

General method: n-Butyllithium (1.7 M hexane solution, 38 mL) was slowly added dropwise to a solution of 2-bromo-4-methylphenol (30 mmol) or 2-bromo-1-ethoxy-4-methylphenol (30 mmol) in anhydrous ethyl ether (80 mL) cooled to -80°C under argon protection. After the dropwise addition was completed, the reaction mixture was allowed to gradually warm up to room temperature and stirred continuously under argon atmosphere for 2 hours. Subsequently, the reaction mixture was cooled again to -80 °C and trimethyl borate (5.58 mL, 50 mmol) was added quickly. After stirring at -80 °C for 0.5 h, the mixture was moved to room temperature and continued to stir under argon atmosphere for 15 h. The reaction was completed with the addition of trimethyl borate (5.58 mL, 50 mmol). After the reaction was completed, 2M HCl aqueous solution (20 mL) was slowly added to the ice-cold reaction mixture and stirred for 0.5 h until the milky emulsion became clear. The ether layer was separated and the aqueous layer was extracted with ether (3 x 100 mL). All ether layers were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The residue was recrystallized with a solvent mixture of hot ether and toluene (3:7 v/v) to give the white solid product (2-hydroxy-5-methylphenyl)boronic acid.

References

[1] Bioorganic and Medicinal Chemistry, 2014, vol. 22, # 24, p. 6908 - 6917
[2] Organic Letters, 2014, vol. 16, # 9, p. 2338 - 2341