Benzothiazole


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Benzothiazole is an aromatic heterocyclic compound with the chemical formula C
7H
5NS. 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.

Benzothiazole
Space filling model of benzothiazole
Space filling model of benzothiazole
Ball-and-stick model of benzothiazole
Ball-and-stick model of benzothiazole
Names
IUPAC name

1,3-Benzothiazole

Identifiers

3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.179 Edit this at Wikidata
UNII

  • InChI=1S/C7H5NS/c1-2-4-7-6(3-1)8-5-9-7/h1-5H check

    Key: IOJUPLGTWVMSFF-UHFFFAOYSA-N check

  • InChI=1/C7H5NS/c1-2-4-7-6(3-1)8-5-9-7/h1-5H

    Key: IOJUPLGTWVMSFF-UHFFFAOYAC

  • n1c2ccccc2sc1

Properties
C7H5NS
Molar mass 135.1863 g/mol
Density 1.238 g/mL
Melting point 2 °C (36 °F; 275 K)
Boiling point 227 to 228 °C (441 to 442 °F; 500 to 501 K)

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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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

This heterocyclic scaffold 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. Some drugs contain this group, examples being riluzole and pramipexole. The heterocycle is found in nature.[2] Accelerators for the sulfur vulcanization of rubber are based on 2-mercaptobenzothiazoles.[3] This ring is a potential component in nonlinear optics (NLO).[4] The compound is also used as an insecticide and food flavoring agent. Benzothiazole, when combined with some chemicals[vague],can be used as a dye in arsenic detection.(see picture).[5]

See also

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

References

  1. ^ T. E. Gilchrist "Heterocyclic Chemistry" 3rd Edition, Longman, 1992.
  2. ^ Lucille Le Bozec, Christopher J. Moody "Naturally Occurring Nitrogen–Sulfur Compounds. The Benzothiazole Alkaloids" Australian Journal of Chemistry 62(7) 639–647.doi:10.1071/CH09126
  3. ^ Hans-Wilhelm Engels, Herrmann-Josef Weidenhaupt, Manfred Pieroth, Werner Hofmann, Karl-Hans Menting, Thomas Mergenhagen, Ralf Schmoll, Stefan Uhrlandt "Rubber, 4. Chemicals and Additives" in Ullmann's Encyclopedia of Industrial Chemistry 2004, Wiley-VCH, Weinheim. doi:10.1002/14356007.a23_365.pub2
  4. ^ Hrobarik, P.; Sigmundova, I.; Zahradnik, P.; Kasak, P.; Arion, V.; Franz, E.; Clays, K. (2010). "Molecular Engineering of Benzothiazolium Salts with Large Quadratic Hyperpolarizabilities: Can Auxiliary Electron-Withdrawing Groups Enhance Nonlinear Optical Responses?". Journal of Physical Chemistry C. 114 (50): 22289–22302. doi:10.1021/jp108623d.
  5. ^ 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. 9 (11): 1779–1785. doi:10.1039/C6AY03302D. ISSN 1759-9679.