Catalysis of the Michael reaction

Laszlo, Pierre; Pennetreau, P.

doi:10.1016/s0040-4039(00)98125-5

Cited by 67 publications

(10 citation statements)

References 13 publications

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“…It has been reported that KF-loaded alumina (KF/ Al 2 O 3 ) shows an efficient solid base catalyst for promoting versatile chemical transformations, such as the Micheal addition, N-, O-and S-alkylation reactions, the Knoevenagel condensation, aldol condensation, Witting-Horner reactions and alkene isomerization [13][14][15][16][17][18][19]. To the best of our knowledge, there is no open literature concerning the solid base of ZnO loaded with KF (KF/ ZnO).…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Biodiesel from Soybean Oil using Heterogeneous KF/ZnO Catalyst

2006

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Biodiesel was produced by transesterification of soybean oil with methanol using ZnO loaded with KF as a solid base catalyst. It was found that the catalyst with 15 wt.% KF loading and calcined at 873 K showed the optimum activity. XRD, IR and Hammett indicator method were employed for the catalyst characterization. The results showed the activity of the catalysts was correlated with their basicity. The influence of various reaction variables on the conversion was also discussed.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Biodiesel from Soybean Oil using Heterogeneous KF/ZnO Catalyst

2006

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“…Of a variety of solid bases, KF/Al 2 O 3 is a typical example. It has been employed as an effective catalyst in a variety of organic reactions including Michael, Knoevenagel and related addition reactions, aldol condensations, hydration of amides, alcoholysis of esters and epoxides, and the Darzens reaction [11][12][13][14][15][16][17][18]. In the present work, feasibility of KF/Al 2 O 3 as a catalyst for the synthesis of PCDLs was investigated.…”

Section: Introductionmentioning

confidence: 99%

KF/Al2O3 as Solid Base for the Synthesis of Polycarbonate Diols (PCDLs)

Feng

Ning

et al. 2007

Catal Lett

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Polycarbonate diols (PCDLs) are known as important intermediate for the manufacture of novel polyurethanes. In this work, a series of KF loaded oxides and alumina doped with potassium halides were prepared and employed as the catalysts for the PCDL synthesis via the reaction of hextane-1, 6-diols (HD) and dimethyl carbonate (DMC) followed by vacuum oligomerization. Experimental results indicated that among the catalysts tested, KF/Al 2 O 3 exhibited the best catalytic activity. Moreover, the catalyst could be reused for three times with acceptable catalytic activity. The basic centres with medium and strong strength generated through the interaction between KF and Al 2 O 3 were catalytically active for the reaction.

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“…These problems, plus the recent increase in the interest of developing environmentally friendly solid catalysts, has led to the development of heterogeneous catalytic systems for this reaction. Examples of such systems are those based on KF-and CsF-alumina, 4 potassium t-butoxide on xonotlite, 5 and Amberlyst A-27, 6 which have been used with different degrees of success. The number of genuinely useful systems however, remains low.…”

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confidence: 99%

Michael Additions Catalysed by N,N-dimethyl-3-aminopropyl - Derivatised Amorphous Silica and Hexagonal Mesoporous Silica (HMS)

Mdoe¹,

Clark²,

Macquarrie³

1998

Synlett

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Solid bases prepared by derivatisation of amorphous silica and hexagonal mesoporous silica with dimethylaminopropyl groups are good catalysts for Michael addition reactions. Of the prepared catalysts, those based on hexagonal mesoporous silica show particularly high activities. The sol-gel method used in preparing the catalysts based on hexagonal mesoporous silica enables loading to be increased to more than twice that of those based on amorphous silica which are prepared by the post-modification method.The Michael addition is a carbon -carbon bond forming reaction important in synthetic chemistry. Typically, the reaction involves a nucleophilic addition of carbanions to α,β-unsaturated carbonyl compounds. During the course of the reaction, electronic charge migrates from the carbon in the donor molecule to a better acceptor atom, usually oxygen, in the electrophile. A base is used to form the carbanion by abstracting a proton from an activated methylene precursor. The reaction is thus base catalysed and in addition to its synthetic utility, may serve as a useful test reaction for studying the catalytic activity of solid bases.Traditionally, the Michael reaction is catalysed by mild to moderately strong bases. Bases such as diisopropylamine, potassium t-butoxide 1 and tetramethylguanidine 2,3 have been used as homogeneous catalysts. However, production of significant amounts of multiple Michael adducts, other side reactions, difficult product separation and catalyst recovery, have always been problematic. These problems, plus the recent increase in the interest of developing environmentally friendly solid catalysts, has led to the development of heterogeneous catalytic systems for this reaction. Examples of such systems are those based on KF-and CsF-alumina, 4 potassium t-butoxide on xonotlite, 5 and Amberlyst A-27, 6 which have been used with different degrees of success. The number of genuinely useful systems however, remains low. As part of a programme aimed at developing heterogeneous base catalysts for use in reactions of synthetic value, we have prepared two catalysts by derivatising amorphous silica and hexagonal mesoporous silica (HMS) with N,N-dimethyl-3-aminopropyl groups. The catalysts were evaluated in the Michael additions of nitroalkanes and α,β-unsaturated carbonyl compounds.The first catalyst (N,N-dimethyl-3-aminopropyl-silica) 1, was prepared according to a known post-modification method 7 using N,N-dimethyl-3-aminopropyltrimethoxysilane (Fluorochem, Derbys, 95%) and silica gel (Kieselgel 100, Merck). Titration with dil. HCl showed a loading of about 0.85 mmol g -1 . Increasing the amount of N,N-dimethyl-3-aminopropylsilane did not increase the loading of the catalyst beyond 1 mmol g -1 , suggesting that this is the maximum loading with this type of preparation method. Thermogravimetric analysis revealed the material to be thermally stable and it does not lose the organic functions until temperatures above 350 o C. Surface area and pore size distribution were determined by N 2 physisorption. The ...

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Catalysis of the Michael reaction

Cited by 67 publications

References 13 publications

Synthesis of Biodiesel from Soybean Oil using Heterogeneous KF/ZnO Catalyst

Synthesis of Biodiesel from Soybean Oil using Heterogeneous KF/ZnO Catalyst

KF/Al2O3 as Solid Base for the Synthesis of Polycarbonate Diols (PCDLs)

Michael Additions Catalysed by N,N-dimethyl-3-aminopropyl - Derivatised Amorphous Silica and Hexagonal Mesoporous Silica (HMS)

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