Friedel-Crafts acylations with modified clays as catalysts

Cornélis, André; Gerstmans, André; Laszlo, Pierre; Mathy, Arthur; Zieba, I.

doi:10.1007/bf00764059

Cited by 79 publications

(30 citation statements)

References 5 publications

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“…Inorganic solids possessing high-surface areas such as alumina, silica, titania, zirconia, ceria, zeolites, clays, etc. are overwhelmingly used as catalysts or supports for dispersing active centres and reagents [5][6][7][17][18][19]. We have been investigating different aspects of green processes with benign solid acid catalysts, which have direct industrial relevance in refineries, petrochemicals, pharmaceuticals, rubber chemicals, dyestuff, agrochemicals, perfumery and flavour chemicals.…”

Section: Introductionmentioning

confidence: 99%

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Yadav

2005

Catal Surv Asia

133

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A large number of inorganic oxides, mixed oxides, including alumina, silica, titania, zirconia, zeolites, carbon, clays and ion exchange resins have been employed as both supports and solid acid catalysts. Clay structure collapses at high temperatures and has to be stablilized. The thermal stability and pore size issues were addressed by pillaring of clays. Natural clays are acid treated or ionexchanged to be used as solid acids, and the acidity and pore structure are dependent on the treatment methodology. Another important class of catalysts is the heteropoly acids (HPA), which are employed as homogeneous or heterogeneous catalysts, having both acid and redox properties. The focus of the current paper is to address the work done in our laboratory on the synergism between clays and heteropoly acids for the development of green processes. A comparison is also provided for the activity of these catalysts with other solid acids. Several alkylation, acylation, isomerization, condensation, dehydration, esterification, nitration and oxidation reactions which are useful in a wide spectrum of industries such as bulk, intermediates, dyes, plasticizer, pharmaceuticals, perfumes, flavours and other fine chemicals were investigated to improve the selectivity of the desired products.

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Section: Introductionmentioning

confidence: 99%

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Yadav

2005

Catal Surv Asia

133

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“…Hence stoichiometric rather than catalytic amounts are required. Recourse to Lewis acidic sites in clays, either exchanged or impregnated with Lewis acidic cations, provides extremely efficient catalysis of Friedel-Crafts alkylations 19,20 and acylations 21 with the environmental asset of vastly reduced, by factors of up to 1000, amounts of catalyst as compared with the standard procedures using aluminum chloride. At least one industrial plant takes advantage of this breakthrough, that we pioneered.…”

Section: Overview Of Our Workmentioning

confidence: 99%

“…We note here in passing that Liège 'clayzic' is activated at 120°C only, whereas York 'clayzic' is activated at 280°C, a higher temperature likely to destroy more of the remaining clay structure. 21 In addition to its high activity, this heterogeneous catalyst, 'clayzic', displays enzyme-like substrate selectivity. 24,[30][31][32][33] Since the amount of 'clayzic' needed for a Friedel-Crafts reaction is catalytic 29 rather than stoichiometric, 33 it is environment friendly, hence its commercialization as an 'Envirocat' by Contract Chemicals.…”

Section: 25mentioning

confidence: 99%

Heterogeneous catalysis of organic reactions

Laszlo

1998

J. Phys. Org. Chem.

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A decade's worth of work is reviewed: building on the demonstrated prowess of heterogeneous catalysis in industrial organic chemistry, the author's laboratory devised efficient catalysts for a number of organic reactions, based on aluminosilicates such as clays and zeolites. This review also spells out, at a time when creative research is overshadowed by imitative research, some of the methological musts that also happen to characterize physical organic chemistry: the devising of experiments so that accurate numerical data can be obtained; the importance of remote, interdisciplinary connections; the need for estrangement from stereotypic preconceptions that may obscure the true explanations for the phenomena; and the over-riding need for concerning oneself only, or at least predominantly, with the important facts that nature tells, if one cares to listen.

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“…[11][12][13][14][15][16][17] Preparation, Characterisation and Evaluation of Brazilian Clay-Based Catalysts J. Braz. Chem.…”

Section: Introductionmentioning

confidence: 99%

“…[11][12][13][14][15][16][17] There have also been studies using other minerals. [18][19][20][21] With respect to esterification, some studies have used commercial, metal-exchanged and heteropoly acid supported montmorillonite.…”

Section: Introductionmentioning

confidence: 99%

Preparation, characterisation and evaluation of brazilian clay-based catalysts for use in esterification reactions

Rezende

Pereira

Santos

et al. 2012

J. Braz. Chem. Soc.

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Catalisadores a base de argilas naturais brasileiras foram preparados, caracterizados, e sua atividade catalítica foi avaliada em reações de esterificação. As argilas naturais foram ativadas por tratamento ácido como recebidas, sem qualquer tratamento prévio. As argilas naturais e as argilas ácidas foram caracterizadas por DRX, TPD-NH 3 , termodessorção de n-butilamina, análise de adsorção de N 2 , FT-IR, TGA e DTA. O desempenho catalítico foi investigado em reações de esterificação de diversos ácidos carboxílicos com diferentes álcoois. As reações foram realizadas com razão molar ácido carboxílico/álcool 1:3, a 100 °C e pressão atmosférica, por 3 h. As argilas ácidas forneceram boas conversões e apresentaram desempenho melhor que a argila comercial K10. Natural Brazilian clay-based catalysts were prepared, characterised, and their catalytic activity was assessed in esterification reactions. The natural clays were acid activated as received, without any previous treatment. Both natural and acid-activated clays were characterised by XRD, NH 3 -TPD, thermodesorption of n-butylamine, N 2 adsorption analysis, FT-IR, TGA and DTA. The catalytic performance was investigated in the esterification of several carboxylic acids with different alcohols. The reactions were carried out in a 1:3 carboxylic acid/alcohol molar ratio at 100 °C and atmospheric pressure for 3 h. The acid-activated clays provided good yields and better performance than commercial clay K10. Keywords: acid activation, clay, smectite, esterification IntroductionEsterification reactions are widely employed in a variety of chemical industries. 1 The procedure generally uses either sulfuric, hydrochloric or sulfonic acid as catalyst. These catalysts generate large quantities of acidic waste, which require appropriate treatment before disposal. The most widely used catalyst is sulfuric acid. It is a low cost reagent and is very active. However, it is also corrosive and presents problems of storage and control. 2 To minimise the problems associated with the homogeneous process, intensive research has been recently devoted to the development of heterogeneous catalysts for esterification. Some examples include functionalised mesoporous materials, 3,4 ion-exchange resin, 1 oxides 5-7 and metal complexes. 8,9 There is considerable interest in developing catalysts based on clays. In terms of their environmental aspect, these materials are one of the most friendly solid catalysts. Additionally, clay-based catalysts are very promising because of the low cost of the raw material, ease of properties manipulation and ease of recovery and reuse. 10 Ion exchange capacity and the potential for increased interlayer spacing are important characteristics of clay minerals that strongly influence their physical-chemical and technological properties. These characteristics, as well as their high surface area, have lead clay minerals to be explored as catalysts. The acid activation method is usually employed to modify the textural characteristics of clays.Clays are being employe...

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Friedel-Crafts acylations with modified clays as catalysts

Cited by 79 publications

References 5 publications

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Heterogeneous catalysis of organic reactions

Preparation, characterisation and evaluation of brazilian clay-based catalysts for use in esterification reactions

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