4-Benzothiazolol

4-Benzothiazolol Property

Melting point:

143℃

Boiling point:

312℃

Density 

1.444

Flash point:

142℃

storage temp. 

Sealed in dry,Room Temperature

form 

solid

pka

7.71±0.40(Predicted)

color 

Light green to green

InChI

InChI=1S/C7H5NOS/c9-5-2-1-3-6-7(5)8-4-10-6/h1-4,9H

InChIKey

NZFKDDMHHUEVPI-UHFFFAOYSA-N

SMILES

S1C2=CC=CC(O)=C2N=C1

Safety

HS Code 

2934208090

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H302Harmful if swallowed

H315Causes skin irritation

H319Causes serious eye irritation

H335May cause respiratory irritation

Precautionary statements

P261Avoid breathing dust/fume/gas/mist/vapours/spray.

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

4-Benzothiazolol Chemical Properties,Usage,Production

Uses

Benzo[d]thiazol-4-ol is a constituent of pheomelanin; a polymeric skin-?centered pigment which acts as a natural photoprotector against harmful solar-?UV radiation.

Synthesis

General procedure for the synthesis of 4-hydroxybenzothiazole from 4-methoxybenzothiazole: Boron bromide (3.09 mL, 1M DCM solution, 3.09 mmol) was slowly added dropwise to a stirring solution of 4-methoxybenzothiazole (510 mg, 3.09 mmol) in anhydrous dichloromethane (30 mL) at 0 °C. The reaction mixture was gradually warmed to 40 °C and stirred continuously overnight. Upon completion of the reaction, the solution was concentrated under vacuum and subsequently diluted with water and 2N hydrochloric acid. The aqueous phase was neutralized to pH 7 with sodium bicarbonate and then extracted with ethyl acetate (3 x 100 mL). The organic extracts were combined, dried with magnesium sulfate, and the solvent was removed under vacuum. The resulting oil was purified by fast chromatography on a silica gel column with the eluent ratio tapered from hexane:ethyl acetate [4:1] to hexane:ethyl acetate [7:3], resulting in 4-hydroxybenzothiazole as a brown solid (730 mg, 80% yield). The NMR hydrogen spectrum (300 MHz, CDCl3) data were as follows: δ 7.59 (1H, s, hydrogen on the thiazole ring), 7.46 (1H, dd, aromatic hydrogen), 7.36 (1H, t, aromatic hydrogen), 7.02 (1H, dd, aromatic hydrogen).

References

[1] Patent: WO2004/43903, 2004, A1. Location in patent: Page 68 - 69
[2] Patent: WO2004/43904, 2004, A1. Location in patent: Page 64 - 65
[3] Patent: WO2004/43931, 2004, A1. Location in patent: Page 42-43
[4] Bioorganic and Medicinal Chemistry Letters, 2010, vol. 20, # 21, p. 6199 - 6202
[5] Helvetica Chimica Acta, 1938, vol. 21, p. 709