Volcanic ash as reusable catalyst in the green synthesis of 3H-1,5-benzodiazepines

PASQUALE, GUSTAVO; CABELLO, CARMEN INÉS; SATHICQ, ANGEL GABRIEL; GAZZOLI, DELIA; MUÑOZ, MERCEDES; ROMANELLI, GUSTAVO PABLO

Green Processing and Synthesis

De Gruyter

Lugar: Berlin; Año: 2019 vol. 8 p. 600 - 610

2191-9542

The volcanic ash from the Andes mountain range (Puyehue-Cordon Caulle volcanic complex situated in western South America on the Argentinean-Chilean border) was used as heterogeneous acid catalyst in the suitable synthesis of 3H-1,5-benzodiazepines. The natural ashes were classified according to their particle size to generate the different catalytic materials. The catalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dis¬persive spectroscopy (EDS), vibrational spectroscopies (FT-IR and Raman), and textural properties were determi¬ned by N2 adsorption (SBET). Potentiometric titration with n-butylamine was used to determine the acidic properties of the catalytic materials. Several 3H-1,5-benzodiazepines were obtained by reaction of o-phenylenediamine and substituted 1,3-diphenyl-1,3-propanedione in solvent-free conditions, giving good to excellent yields of a variety ben¬zodiazepines. The method was carried out in environmen¬tally friendly conditions and it was operationally simple. The volcanic ash resulted in a safe and recyclable catalyst