Direct alkenylation of aromatics with phenylacetylene over supported H3PW12O40 catalysts as a clean and highly efficient approach to producing α-arylstyrenes

Supported phosphotungstic acid catalyst on modified activated carbon for Friedel–Crafts alkenylation of diverse aromatics to their corresponding α-arylstyrenes

“…From Fig. 2, four characteristic peaks corresponding to P-O (␣-peak, at around 1080 cm −1 ), W O (␤-peak, at around 982 cm −1 ), and W O W (␥-and ␦-peaks, at around 893-798 cm −2 ) appear on all of the samples, suggesting that the typical Keggin structure can be remained after being supported on AC [10,20]. The continuously intensified adsorption peaks with the increased PTA loadings are not surprised.…”

“…Moreover, we cannot see any medium acid sites on the assynthesized PTA/AC catalysts. However, the medium acidic sites on PTA/MCM-41 were definitely observed even if the 10 wt.% of low PTA loading [10]. Then why do the acid site strengths increase with larger PTA crystallite sizes?…”

“…The AC surface modification process via H 2 O 2 oxidation pretreatment was performed as follows: a certain amount of AC was immersed into a 35 wt.% H 2 O 2 aqueous solution (5 ml g −1 AC) in a water-ice bath with continuously stirring for 6 h. The sample was filtered, washed with deionized water, and followed by drying at 105 • C overnight, and then the modified AC supports were obtained. The PTA/AC catalysts with diverse PTA loadings (10,20,30, and 40 wt.%) were prepared by wet impregnation method. The typical wet impregnation process is as follows: 0.23 g PTA (analytical reagent, AR, bought from China National Medicines Corp. Ltd.) was dissolved into 10 ml deionized water to obtain PTA impregant.…”

“…Not like the well-established Friedel-Crafts alkylation, the Friedel-Crafts alkenylation still remains a rigorous challenge to be resolved. The biggest issue is to efficiently eliminate the oligomerization of alkynes owing to the poor stability of alkenyl cation species [8][9][10][11]. However, the rare reports on alkenylation over solid acid catalysts can be found.…”

“…We previously demonstrated that the supported PTA catalyst on MCM-41 under optimized conditions exhibited good catalytic performance in alkenylation. It was found that supported PTA catalyst could be a promising catalyst for the clean production of ␣-arylstyrenes [10]. However, further improvement in catalytic activity, selectivity and the expansion in reactants scope are required.…”