BENZOTHIOPHENE-4-CARBOXYLIC ACID

BENZOTHIOPHENE-4-CARBOXYLIC ACID Property

Melting point:

188-189℃

Boiling point:

376.2±15.0 °C(Predicted)

Density 

1.419±0.06 g/cm3 (20 ºC 760 Torr)

storage temp. 

Sealed in dry,Store in freezer, under -20°C

pka

3.34±0.10(Predicted)

Appearance

Off-white to light brown Solid

Safety

Hazard Codes 

Xn

Risk Statements 

22

HS Code 

2934999090

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H302Harmful if swallowed

H319Causes serious eye irritation

Precautionary statements

P264Wash hands thoroughly after handling.

P264Wash skin thouroughly after handling.

P270Do not eat, drink or smoke when using this product.

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

P301+P312IF SWALLOWED: call a POISON CENTER or doctor/physician IF you feel unwell.

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

P330Rinse mouth.

P501Dispose of contents/container to..…

BENZOTHIOPHENE-4-CARBOXYLIC ACID Chemical Properties,Usage,Production

Synthesis

Benzo[b]thiophene-4-carboxylic acid was prepared as follows: a small amount of iodine crystals was added as initiator to a stirring suspension of magnesium (Mg, 4.79 g, 197 mmol) in anhydrous tetrahydrofuran (THF, 100 mL) under nitrogen protection. Subsequently, a solution of 4-bromobenzo[b]thiophene (40.0 g, 188 mmol) in anhydrous THF (150 mL) was added slowly and dropwise. Initially, only 5% of the total amount (~1 mL) was added to initiate the reaction, after which the remaining solution was added at a rate that maintained the reaction temperature at 50-55 °C, a process that took about 30 min. After addition, the reaction mixture was continued to be stirred at 50°C for 1 hour. After most of the magnesium has been consumed, the reaction is cooled to 23°C and carbon dioxide (CO2) gas produced from dry ice is passed into the solution. The reaction is exothermic and the solution temperature needs to be maintained at about 23°C by an ice bath. The gas is continuously vented for 15-20 minutes until a large amount of precipitate generation is observed. Upon completion of the reaction, the reaction is carefully quenched with 10% aqueous hydrochloric acid (HCl) solution at 0°C. Saturated aqueous sodium chloride solution was added and the mixture was extracted with ethyl acetate (EtOAc). The organic phase was extracted with 2 M aqueous sodium hydroxide (NaOH) and subsequently the aqueous phase was acidified to pH 1 with 37% aqueous HCl to form a suspension. After filtration and drying, benzo[b]thiophene-4-carboxylic acid was obtained as a white solid (24.9 g, 74% yield).

References

[1] Patent: US2008/306082, 2008, A1. Location in patent: Page/Page column 18