This study was performed for the development of a green and promising approach for the synthesis of methyl acrylate and acrylic acid by a one‐step aldol condensation reaction of dimethoxymethane and methyl acetate ov...This study was performed for the development of a green and promising approach for the synthesis of methyl acrylate and acrylic acid by a one‐step aldol condensation reaction of dimethoxymethane and methyl acetate over cesium oxide‐supported on ZSM‐35 zeolite catalysts; the effect of base sites as well as acid sites on the aldol condensation reaction was studied in detail. It was found that base sites were harmful for aldol condensation due to their failure in catalyzing the decomposition of dimethoxymethane precursor into formaldehyde, whereas the acid site was indispensable for the reaction to proceed. This reaction cannot take place without an acid site. Although acid sites in H‐form of the zeolite（HZSM‐35） are indispensable for the aldol condensation reaction, not all of them tend to favor this reaction. A strong acid catalyzes methanol‐to‐olefin‐like reactions resulting in hydrocarbon byproducts, which are finally transferred to hard coke. Medium strong acids and weak acids are great candidates for the target aldol condensation reaction with high activity and selectivity. A γ‐Al2O3 sample with abundant weak‐strength Lewis acid sites, together with a few medium‐strong‐strength acid sites, performs well with a high activity and considerable stability during the synthesis of methyl acrylate and acrylic acid.展开更多
Aromatic ketones are directly alkylated at a position with primary alcohols at 110 ℃ in the presence of catalytic amount of KOH and [Cp＊lrC12]2 （Cp＊=pentamethylcyclopentadienyl） catalyst. The reaction is carried ...Aromatic ketones are directly alkylated at a position with primary alcohols at 110 ℃ in the presence of catalytic amount of KOH and [Cp＊lrC12]2 （Cp＊=pentamethylcyclopentadienyl） catalyst. The reaction is carried out in the absence of any solvent or additive, which generates only water as the byproduct in theory. It is very efficient and generally completed in 10 min in good isolated yields. The reaction is believed to undergo successive hydrogen transfer and cross aldol condensation processes.展开更多
文摘This study was performed for the development of a green and promising approach for the synthesis of methyl acrylate and acrylic acid by a one‐step aldol condensation reaction of dimethoxymethane and methyl acetate over cesium oxide‐supported on ZSM‐35 zeolite catalysts; the effect of base sites as well as acid sites on the aldol condensation reaction was studied in detail. It was found that base sites were harmful for aldol condensation due to their failure in catalyzing the decomposition of dimethoxymethane precursor into formaldehyde, whereas the acid site was indispensable for the reaction to proceed. This reaction cannot take place without an acid site. Although acid sites in H‐form of the zeolite（HZSM‐35） are indispensable for the aldol condensation reaction, not all of them tend to favor this reaction. A strong acid catalyzes methanol‐to‐olefin‐like reactions resulting in hydrocarbon byproducts, which are finally transferred to hard coke. Medium strong acids and weak acids are great candidates for the target aldol condensation reaction with high activity and selectivity. A γ‐Al2O3 sample with abundant weak‐strength Lewis acid sites, together with a few medium‐strong‐strength acid sites, performs well with a high activity and considerable stability during the synthesis of methyl acrylate and acrylic acid.
文摘Aromatic ketones are directly alkylated at a position with primary alcohols at 110 ℃ in the presence of catalytic amount of KOH and [Cp＊lrC12]2 （Cp＊=pentamethylcyclopentadienyl） catalyst. The reaction is carried out in the absence of any solvent or additive, which generates only water as the byproduct in theory. It is very efficient and generally completed in 10 min in good isolated yields. The reaction is believed to undergo successive hydrogen transfer and cross aldol condensation processes.
