2-Chlorobenzothiazole

Chemical Properties

CLEAR YELLOW TO YELLOW-BROWNISH LIQUID

Uses

2-Chloro-1,3-benzothiazole is used in the synthesis of CBTs which are good building blocks for bioluminescent compounds for imaging.

Uses

2-Chlorobenzothiazole was used in the synthesis of:

• (RS)- and (S)-lubeluzole
• (1,3-benzothiazol-2-yl) amino-9-(10H)-acridinone derivatives
• 4H-thieno[2′,3′:4,5]pyrimido[2,1-b]benzothiazole derivatives

Synthesis

95-16-9

615-20-3

The general procedure for the synthesis of 2-chlorobenzothiazole from benzothiazole was as follows: benzothiazole (1 mmol, 135.9 mg) and carbon tetrachloride (1.1 mmol, 169.2 mg) were placed in a 10 mL round bottom flask. 5 mL of N,N-dimethylformamide and sodium tert-butoxide (4.0 mmol, 384.4 mg) were added to the reaction system and stirred thoroughly to ensure that the reactants were homogeneously mixed. The reaction was carried out at room temperature for 3 h, during which the progress of the reaction was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was poured into water and extracted with dichloromethane. The organic phase was separated and dried with anhydrous sodium sulfate. Subsequently, the dichloromethane was removed by rotary evaporator to obtain the crude product. The crude product was purified by silica gel column chromatography using a mixed solvent of petroleum ether and ethyl acetate as eluent (30:1, v/v). 2-Chlorobenzothiazole (brown oily liquid, 149.2 mg) was finally obtained in 88% yield.

Purification Methods

It is purified by fractional distillation in vacuo. The 2-chloro-3-methylbenzothiazolinium 2,4-dinitrobenzenesulfonate crystallises from Ac2O, m 162-163o(dec). [Young & Amstutz J Am Chem Soc 73 4773 1951, Brower et al. J Org Chem 19 1830 1954, Hunter & Jones J Chem Soc 2190 1930, Beilstein 27 H 44, 27 II 18, 27 III/IV 1072.]

References

[1] Organic and Biomolecular Chemistry, 2018, vol. 16, # 6, p. 886 - 890
[2] Patent: CN107501023, 2017, A. Location in patent: Paragraph 0063; 0064
[3] Organic Letters, 2009, vol. 11, # 2, p. 421 - 423
[4] Journal of Organic Chemistry, 2009, vol. 74, # 21, p. 8309 - 8313
[5] Chemische Berichte, 1880, vol. 13, p. 16