Alumina as a Support and Catalyst for the Synthesis of Benzothiazoles in Solvent‐free Condition. Issue 6 (11th March 2013)

• Record Type: Journal Article
• Authors: Ding, Mei‐Fang; Chen, Chia‐Pei; Lin, Shaw‐Tao
• Is Part Of: Journal of the Chinese Chemical Society. Volume 60:Issue 6(2013:Jun.)
• Page Start: 645
• Page End: 649
• Publication Date: 2013-03-11
• Subjects: Chemistry -- Periodicals; Electronic journals; 540.5
• DOI: 10.1002/jccs.201200413
• Languages: English
• ISSNs: 0009-4536

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Arylbenzothiazole (<bold>4</bold>) and benzothiazolylcoumarins (<bold>5</bold>) were prepared by the condensation of 2‐aminothiophenol (<bold>1</bold>) and hydroxybenzaldehydes (<bold>2</bold>) and 3‐ethoxycarbonylcoumarinnin (<bold>3</bold>), respectively, in solvent‐free condition. Of the solid support used, γ‐Al₂O₃ demonstrated the best activity. A linear regression line obtained from correlation between relative formation rate and Hammett constants with slope of 0.653 suggested that this condensation process is less sensitive to the substituents on the phenyl ring due to low efficacy of polarization in the solid state. In general, good yields (&gt;80% yield) were obtained for the formation of <bold>4</bold>. Conversely, yields of <bold>5</bold> were poor, because of γ‐Al₂O₃ catalytic decomposition of <bold>3</bold> to form <bold>2</bold> (without P₂O₅) and coumarin (with P₂O₅).</p> </abstract>