Journal
MOLECULAR CATALYSIS
Volume 485, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.mcat.2020.110842
Keywords
Mesoporous-microporous silica; Tungstophosphoric acid; 3H-1,5-benzodiazepine
Categories
Funding
- Universidad de Malaga (Spain)
- Universidad Nacional de La Plata [X773]
- CONICET [PIP 0449]
- Ministerio de Ciencia, Innovacion y Universidades [RTI2018-099668-BC22]
- Ministerio de Economia y Competitividad [RyC-201517870]
- Junta de Andalucia [UMA18-FEDERJA-126]
- FEDER funds
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Solid acid catalysts were successfully prepared using mesoporous silica (MESOSI) as support and tungstophosphoric acid (KTPA) as active phase, which was incorporated by impregnation (MESOSI#KTPA) and inclusion (MESOSI@KTPA). TEM (transmission electron microscopy) images of MESOSI samples revealed the presence of mesopores (worm-like structured) and well-defined pore channels. XRD patterns of MESOSI#KTPA samples showed small crystals of H3PW12O40 center dot 6H(2)O that were not present in the MESOSI@KTPA materials. The specific surface area of the MESOSI modified with KTPA decreases with the increment of the heteropolyacid content. P-31 NMR and FT-IR characterizations confirmed the existence of undegraded [H3-xPW12O40](x-) and [PW12O40](3-) anions interacting with the (math)Si-OH(2)(+)groups of MESOSI. Potentiometric titration results showed that both acid strength and number of acid sites increased with the KTPA loading in MESOSI@KTPA and MESOSI@KTPA samples. Moreover, the acidic properties of MESOSI#KTPA materials were remarkably higher than those of MESOSI@KTPA. The catalysts prepared were highly active, selective and reusable in the solvent-free synthesis of 3H-1,5-benzodiazepine from 1,2-phenylenediamine and 1,3-dipheny1-1,3-propanedione.
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