Host (nanocage of zeolite–Y)/guest (manganese(II), cobalt(II), nickel(II) and copper(II) complexes of 12-membered macrocyclic Schiff-base ligand derived from thiosemicarbazide and glyoxal) nanocomposite materials: Synthesis, characterization and catalytic oxidation of cyclohexene

✍ Scribed by Masoud Salavati-Niasari

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 506 KB
• Volume: 283
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/j.molcata.2007.12.015

✦ Synopsis

A series of Mn(II), Co(II), Ni(II) and Cu(II) complexes with 12-membered macrocyclic tetradentate ligand; H 6 C 6 N 6 S 2 = 1,2,5,6,8,11hexaazacyclododeca-7,12-dithione-2,4,8,10-tetraene; have been synthesized and characterized as homogeneous and encapsulated into the nanopores of zeolite-Y. These catalytic systems show a good activity in the oxidation of cyclohexene to 2-cyclohexene-1-one, 2-cyclohexene-2-ol and 1-(tert-butylperoxy)-2-cyclohexene. The chelation of zeolite-exchanged metal(II) by N-containing ligand gives rise to a whole class of Host-Guest Nanocomposite Materials (HGNM) as heterogeneous liquid-phase oxidation, which exhibits similar catalytic performances than the homogeneous ones. The encapsulated complexes abbreviated here as [M(H 4 C 6 N 6 S 2 )]-NaY, catalyze the oxidation of cyclohexene using TBHP as oxidant in good yield. Cyclohexene catalyzed by [M(H 4 C 6 N 6 S 2 )]-NaY under optimized reaction conditions gave three reaction products namely, 2-cyclohexene-1one, 2-cyclohexene-2-ol and 1-(tert-butylperoxy)-2-cyclohexene. In the presence of tert-butylhydroperoxide all catalysts gave 2-cyclohexene-1-one in major yield, though overall conversion has been found low (40-90%).