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

TY - JOUR

T1 - Dual behavior of ZSM-5 as bronsted acid and electron acceptor in the adsorption of N,N'-diphenylhydrazine

AU - Martí, Vicente

AU - Fornés, Vicente

AU - García, Hermenegildo

AU - Roth, Heinz Dieter

PY - 2000/2

Y1 - 2000/2

N2 - 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.

AB - 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.

KW - Electron transfer

KW - Proton transfer

KW - Radical cation

KW - Zeolites

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U2 - https://doi.org/10.1002/(SICI)1099-0690(200002)2000:3<473::AID-EJOC473>3.0.CO;2-N

DO - https://doi.org/10.1002/(SICI)1099-0690(200002)2000:3<473::AID-EJOC473>3.0.CO;2-N

M3 - Article

SN - 0075-4617

SP - 473

EP - 477

JO - Justus Liebigs Annalen der Chemie

JF - Justus Liebigs Annalen der Chemie

IS - 3

ER -