Mono-copper substituted phosphotungstate supported on to neutral alumina: Synthesis, characterization and detailed studies for oxidation of styrene

Magnetic Thiaminum Octamolybdate Nanocatalyst for Oxygenation of Styrenes to Benzaldehydes and Tandem Synthesis of Benzimidazoles

“…63 Many previously reported oxygenation catalysts based on polyoxomolybdates contained low valent elements in addition to Mo VI but not necessarily Mo in lower oxidation states than Mo-(VI). [24][25][26]28,29,56,63,64 In our system, thiaminium might partially reduce Mo VI to Mo V and Mo IV as confirmed by our XPS results and in line with similar observations for the compound (VB) 2 [HPMo 12 O 40 ]•6DMF. 31 For the previously reported system Fe 3 O 4 @SiO 2 /(NH 4 ) 6 Mo 7 O 24 , no such "reductive activation" seemed to be necessary.…”

“…Catalytic control experiments in the presence of established scavengers were performed to further elucidate the active species and reaction mechanism (Figure 5). 54 The finding that only 12% styrene was converted to benzaldehyde over the catalyst when using only 0.05 mmol TBHP (Figure 3B) showed that aerial O 2 plays no role in the process, 29,55 which was further supported by the smooth progress of the reaction under an Ar atmosphere. This stands in contrast to a number of previously reported procedures in which TBHP was only needed as an activator while O 2 was found to be the oxidant.…”

“…Polyoxometallates (POMs) have turned out to be versatile platforms for oxidation/oxygenation catalysis in solution or in supported heterogeneous systems. − Among them, polyoxomolybdates are frequent owing to the redox-active Mo­(VI) which is also important in molybdenum-dependent redox enzymes in biology . In many of the reported polyoxomolybdate catalysts for oxygenation reactions, the POM catalysts contain other atoms with inherently lower oxidation states such as P­(V) , or Zr­(IV) were garnished with transition metal complexes. Multicomponent (hybrid) heterogeneous structures and composites are frequent. − …”

Solvent Free, Selective Oxidation of Styrene Catalyzed by Cobalt Acylpyrazolone Supported onto Neutral Alumina: Synthesis and Spectral Characterization

“…These shifts and missing bands in [Co(HL B ) 2 /Al 2 O 3 ] likely result from chemical interactions between the complex and the alumina. [40] , the TGA analysis shows an initial weight loss of approximately 13 % within the temperature range of 100 to 380 °C. This weight loss at higher temperatures may be attributed to the removal of coordinated water molecules that are stabilized with hydrogen bonding with the hydroxyl groups on the alumina support.…”

Impregnation Synthesized Cu@MIL‐101(Cr) Catalyzes the Oxidation of Styrene to Benzaldehyde with TBHP**

“…The comparison of Cu@MIL-101(Cr) and some reported catalysts about styrene oxidation reaction with TBHP to produce benzaldehyde was shown in Table 3. [46][47][48][49] It is obvious that Cu@MIL-101(Cr) has both significantly higher conversion of styrene and selectivity of benzaldehyde, although other catalysts listed in Table 3 have some advantages, such as shorter reaction time or the solvent-free condition. In fact, there is still a remarkable superiority in the yield of benzalde- ).…”