Dual Behavior of ZSM-5 as Brønsted Acid and Electron Acceptor in the Adsorption ofN,N′-Diphenylhydrazine

Generation and Reactions of Organic Radical Cations in Zeolites

“…One such case involves adsorption of N,N′-diphenylhydrazine (66) on HZSM-5, yielding azobenzene (67) and aniline (59). 259 The products were explained by competing pathways, initiated by ET to or protonation by zeolite active sites; details will be discussed in Section V.B. However, we note briefly that the benzidine rearrangement that would form 59, typically observed for 66 in acid large-pore zeolites, 260 is frustrated in the narrow channels of ZSM-5, since the required folded conformation cannot be accommodated.…”

“…As noted above, acid zeolites, are proton donors as well as electron acceptors; however, the concurrent involvement of these intermediates has not been documented often. One such case involves adsorption of N , N ‘ -diphenylhydrazine ( 66 ) on HZSM-5, yielding azobenzene ( 67 ) and aniline ( 59 ) . The products were explained by competing pathways, initiated by ET to or protonation by zeolite active sites; details will be discussed in Section V.B.…”

“…However, the concurrent involvement of these intermediates has not been documented very often. One such case involves adsorption of N , N ‘ -diphenylhydrazine, 66 , on HZSM-5, yielding azobenzene ( 67 ) and aniline ( 59 ) . The mass balance after solid−liquid extraction was incomplete (∼75%), indicating that some organic material was retained in the solid; the IR spectrum of the extracted solid corresponded to that of 59 .…”

Spontaneous doping and magnetic properties of polyacetylene and polypropyne synthesized in situ in Ni-exchanged mordenite and mesoporous MCM-41

“…8 A well-established property of zeolites is their ability to spontaneously generate radical cations upon incorporation of electron-rich organic guests. The types of molecule whose radical cations have been detected in zeolites include amines, [9][10][11] sulfur heterocycles, [12][13][14][15][16] polycyclic aromatic hydrocarbons 17 and a,o-diphenylpolyenes. [18][19][20] In fact, generation of minute but detectable amounts of acetylene radical cation by adsorption of acetylene on H-mordenite has already been reported.…”