Chinese Journal of Catalysis ›› 2015, Vol. 36 ›› Issue (5): 757-763.DOI: 10.1016/S1872-2067(14)60302-8

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Fructose-catalyzed synthesis of tetrahydrobenzo[b]pyran derivatives: Investigation of kinetics and mechanism

Sayyedeh Shadfar Pourpanah, Sayyed Mostafa Habibi-Khorassani, Mehdi Shahraki   

  1. Department of Chemistry, University of Sistan and Baluchestan, Zahedan, Iran
  • Received:2014-12-16 Revised:2015-01-19 Online:2015-04-17 Published:2015-04-17
  • Contact: Sayyed Mostafa Habibi-Khorassani

Abstract:

Fructose was used as an efficient catalyst for three-component condensation reactions of aryl aldehydes, malononitrile, and dimedone in a mixture of EtOH and H2O as green solvents. The advantages of this method are a short reaction time, high yields, low cost, easy accesses, and simple work-up. The mechanism of the synthesis of a derivative of 4H-tetrahydrobenzo[b]pyran was clarified using spectroscopic kinetic methods. The activation energy (Ea = 65.34 kJ/mol) and related kinetic parameters (ΔG = 69.14 kJ/mol, ΔS = 20.99 J/(mol·K), and ΔH = 62.89 kJ/mol) were calculated, based on the effects of temperature, concentration, and solvent. The first step in the proposed mechanism was identified as the rate-determining step (k1), based on the steady-state approximation.

Key words: Fructose, Catalyst, Kinetics, Mechanism, Tetrahydrobenzo[b]pyran derivative