Dual behavior of ZSM-5 as bronsted acid and electron acceptor in the adsorption of N,N'-diphenylhydrazine

Vicente Martí, Vicente Fornés, Hermenegildo García, Heinz Dieter Roth

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Incorporation of N,N'-diphenylhydrazine into HZSM-5 led to the formation of azobenzene and aniline (70-80 mol-% mass balance). The formation of azobenzene can be followed by the appearance in diffuse reflectance UV/Vis spectroscopy of a characteristic band (λmax = 420 nm). IR spectra of the extracted solids indicate that some aniline is retained in the zeolite, probably due to acid-base interaction with active sites. The products are rationalized by two competing mechanisms: the formation of azobenzene by electron transfer to an oxidizing site, the generation of aniline by proton transfer from a Bronsted acid site. A long-wavelength diffuse-reflectance band (λmax = 800 nm) in the initial stages of the reaction supports the intermediacy of a radical cation. These results show that acid zeolites can exhibit a dual behavior against basic substrates with low oxidation potential, serving simultaneously as electron acceptor and Bronsted acid.

Original languageEnglish (US)
Pages (from-to)473-477
Number of pages5
JournalEuropean Journal of Organic Chemistry
Issue number3
DOIs
StatePublished - Feb 2000

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry

Keywords

  • Electron transfer
  • Proton transfer
  • Radical cation
  • Zeolites

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