Benzothiazole Explained

Benzothiazole, or more specifically 1,3-benzothiazole, is an aromatic heterocyclic compound with the chemical formula . It is colorless, slightly viscous liquid. Although the parent compound, benzothiazole is not widely used, many of its derivatives are found in commercial products or in nature. Firefly luciferin can be considered a derivative of benzothiazole.

The three structural isomers of benzothizaole are 1,3-benzothiazole, 1,2-benzothiazole and 2,1-benzothiazole.

Structure and preparation

Benzothiazoles consist of a 5-membered 1,3-thiazole ring fused to a benzene ring. The nine atoms of the bicycle and the attached substituents are coplanar.

Benzothiazoles are prepared by treatment of 2-mercaptoaniline with acid chlorides:^[1]

C₆H₄(NH₂)SH + RC(O)Cl → C₆H₄(NH)SCR + HCl + H₂O

Uses

Benzothiazole occurs naturally in some foods but is also used as a food additive.^[2] It has a sulfurous odor and meaty flavor.^[3] The European Food Safety Authority assessment had "no safety concern at estimated levels of intake as a flavouring substance".^[4]

The heterocyclic core of the molecule is readily substituted at the unique methyne centre in the thiazole ring. It is a thermally stable electron-withdrawing moiety with numerous applications in dyes such as thioflavin.^[5] Some drugs contain this group, examples being riluzole and pramipexole. Accelerators for the sulfur vulcanization of rubber are based on 2-mercaptobenzothiazoles. This ring is a potential component in nonlinear optics (NLO).^[6] A benzothiazole derivative is suggested as a dye for arsenic detection.^[7]

See also

• Benzothiazoles are related to thiazoles, which lack the fused benzene ring.
• Benzoxazoles, which substitute an oxygen for the sulfur atom.

External links

• MSDS

Notes and References

1. T. E. Gilchrist "Heterocyclic Chemistry" 3rd Edition, Longman, 1992.
2. 10.1071/CH09126 . Naturally Occurring Nitrogen–Sulfur Compounds. The Benzothiazole Alkaloids . 2009 . Le Bozec . Lucille . Moody . Christopher J. . Australian Journal of Chemistry . 62 . 7 . 639 .
3. Web site: Benzothiazole . The Good Scents Company . 2020-10-06 .
4. 10.2903/j.efsa.2008.875 . free. Flavouring Group Evaluation 76, (FGE.76) - Consideration of sulphur-containing heterocyclic compounds evaluated by JECFA (59th meeting) structurally related to thiazoles, thiophene, thiazoline and thienyl derivatives from chemical group 29, miscellaneous . EFSA Journal . 2008 . 6 . 11 . 875 .
5. 10.1002/ardp.201400340. Recent Advances in the Chemistry and Biology of Benzothiazoles . 2015 . Gill . Rupinder K. . Rawal . Ravindra K. . Bariwal . Jitender . Archiv der Pharmazie . 348 . 3 . 155–178 . 25682746 . 10421792 . free .
6. Journal of Physical Chemistry C . 2010 . 114 . 22289–22302 . Hrobarik . P. . Sigmundova, I. . Zahradnik, P. . Kasak, P. . Arion, V. . Franz, E. . Clays, K. . 3. Molecular Engineering of Benzothiazolium Salts with Large Quadratic Hyperpolarizabilities: Can Auxiliary Electron-Withdrawing Groups Enhance Nonlinear Optical Responses? . 10.1021/jp108623d . 50.
7. Chauhan. Kalpana. Singh. Prem. Kumari. Bhawana. Singhal. Rakesh Kumar. 2017-03-16. Synthesis of new benzothiazole Schiff base as selective and sensitive colorimetric sensor for arsenic on-site detection at ppb level. Analytical Methods. en. 9. 11. 1779–1785. 10.1039/C6AY03302D. 1759-9679.