Highly effective green oxidation of aldehydes catalysed by recyclable tungsten complex immobilized in organosilanes-modified SBA-15

Assembly of SBA‐15 Derived Hybrid Heterogeneous Catalysts for Liquid Phase Cyclopentene Epoxidation

“…As shown in Figure 4, in the spectra of SBA‐15‐NH 2 , SBA‐15‐NH(PO 3 H 2 ), and SBA‐15‐NH(PO 3 H 2 )‐W, the characteristic bands detected at 2940 and 2885 cm −1 were corresponded to ν(C−H). The band at 670 cm −1 was ascribed to N−H stretching vibration [17] . The peak corresponded to phosphoramide at 1230 cm −1 was not clearly observed, and this might be ascribed to the coverage of the broad peak of ν as (Si−O−Si) [20] .…”

“…Besides, as depicted in Figure 3, after modification of SBA‐15 with ionic liquid ImCl‐PF 6 , SBA‐15‐ImCl‐PF 6 material exhibited characteristic peaks at 1656 cm −1 , which was associated with ν(C=N) [16] . Three new IR bands at 2960, 2931, and 2860 cm −1 assigned to ν(C−H) were seen clearly for SBA‐15‐ImCl‐PF 6 and SBA‐15‐ImCl‐PF 6 ‐W materials [17] . Nevertheless, compared with SBA‐15, the intensity of Si−OH band located at 960 cm −1 of SBA‐15‐ImCl‐PF 6 decreased after the incorporation of ImCl‐PF 6 moieties to SBA‐15, which was attributed to the reaction between non‐condensed Si−OH groups and ImCl‐PF 6 moieties [18] .…”

“…As seen in Figure 9, TG analysis was applied to investigate thermal stability of the chemical functionalized materials since the observed mass loss was connected with the loss of the organic moieties attached to the surface and tungsten species. Weight loss from 30 to 100 °C was ascribed to physically absorbed water [17] . A larger weight loss within the range was observed in SBA‐15 because of many Si−OH moieties on the surface, whereas chemical functionalized materials displayed smaller loss owing to the organic groups grafted.…”

“…A larger weight loss within the range was observed in SBA‐15 because of many Si−OH moieties on the surface, whereas chemical functionalized materials displayed smaller loss owing to the organic groups grafted. The mass loss of SBA‐15 between 200∼800 °C was attributed to Si−OH groups dehydroxylation [17] . Compared with SBA‐15, the larger weight loss of SBA‐15‐ImCl‐PF 6 , SBA‐15‐NH(PO 3 H 2 ), and SBA‐15‐N + within 200∼800 °C was assigned to organic moieties decomposition.…”

“…The band at 670 cm À 1 was ascribed to NÀ H stretching vibration. [17] The peak corresponded to phosphoramide at 1230 cm À 1 was not clearly observed, and this might be ascribed to the coverage of the broad peak of ν as (SiÀ OÀ Si). [20] The observed bands at 949, 889, 624, and 545 cm À 1 were assigned to ν(W=O), ν(OÀ O), ν asym (W(O 2 )), and ν sym (W(O 2 )), respectively.…”