Aldol Condensations on Solid Catalysts: A Cooperative Effect between Weak Acid and Base Sites

Climent, María J.; Corma, Avelino; Fornés, Vicente; Guil-López, R.; Iborra, Sara

doi:10.1002/1615-4169(200212)344:10<1090::aid-adsc1090>3.0.co;2-x

Cited by 126 publications

(81 citation statements)

References 11 publications

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“…Acetone is converted into diacetone alcohol by an aldol reaction on acid, base, and acid-base pair sites [12,[19][20][21], and then converted into mesityl oxide by subsequent dehydration on acid sites. The base catalyst showed higher efficiency than acid catalysts for this reaction in general.…”

Section: Resultsmentioning

confidence: 99%

Surface Base Sites of MgO Covered with Al2O3: XANES Analysis of Al and Mg K-edges

et al. 2010

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Section: Resultsmentioning

confidence: 99%

Surface Base Sites of MgO Covered with Al2O3: XANES Analysis of Al and Mg K-edges

et al. 2010

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“…It is commonly known that the jasminaldehyde condensation occurs in the presence of a catalyst [1][2][3][4][5][6]. For the condensation of jasminaldehyde on UiO-66 as catalyst, we propose a mechanism that includes 6 steps ( Figure 5a).…”

Section: Reaction Mechanism Of the Cross Aldol Condensation On Uio-66mentioning

confidence: 99%

“…This fine chemical compound of jasmine odor is commonly referred to by its commercial name jasminaldehyde and is most widely applied in the perfume industries [1]. The jasminaldehyde condensation reaction invariably goes along with the self-condensation of heptanal, leading to a major by-product, 2-pentylhept-2-enal ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Mechanistic studies of aldol condensations in UiO-66 and UiO-66-NH 2 metal organic frameworks

Hajek

Vandichel

Voorde

et al. 2015

Journal of Catalysis

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Abstract:A full mechanistic investigation is proposed for the industrially important cross aldol condensation reaction of heptanal with benzaldehyde on the UiO-66 and the amino-functionalized UiO-66-NH 2 metal-organic frameworks to form jasminaldehyde. Several experimental studies indicate that the activity for the aldol condensation reaction can be increased by proper functionalization of the material, e.g. by introducing an additional basic amino site and thus creating a bifunctional acid-base catalyst for the aldol condensation. The precise molecular level origin for this behavior is to date unclear. Herein state-of-the-art Density-Functional Theory (DFT) calculations have been performed to unravel the mechanism of the cross and self aldol condensation of benzaldehyde and propanal. To this end free energy calculations have been performed both on extended cluster and periodic models. It is found that the mechanism on both catalysts is essentially the same, although a slightly stronger adsorption of the reactants and slightly lower barriers were found on the amino functionalized material, pointing towards higher initial activities. New experiments were performed to confirm these observations. It is indeed found that the initial activity towards cross aldol condensation on the amino functionalized material is higher, although after about 40 min of reaction both materials become equally active. Our results furthermore point out that the basic amino groups may promote side reactions such as imine formation, which is induced by water. The study as presented can assist to engineer materials at the molecular level towards the desired products.

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“…These heterogeneous catalysts are typically basic catalysts such as hydrotalcites [11], anion exchange resins [12], or MgO [13] among others. Recently, it was demonstrated that heterogeneous catalysts were able to effectively catalyze condensation reactions through acid-base cooperative catalysis [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Aldol Condensations Using Bio-oil Model Compounds: The Role of Acid–Base Bi-functionality

2010

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The aldol condensation of acetaldehyde, acetone, and methyl ethyl ketone, which represent model biooil compounds, in the condensed phase, was performed using a bi-functional aluminophosphate catalyst. It was found that increasing the number and strength of the basic sites while decreasing acid sites on the catalyst caused a reduction in yield of the condensation products. In contrast, the addition of organic acids such as acetic acid at low concentrations to the catalyst-containing reaction mixture was found to increase activity. The presence of both acid and base sites was found to be necessary and their relative number was important for both the activity and selectivity of the condensation reaction. A mechanism explaining the observed phenomena was proposed.

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Aldol Condensations on Solid Catalysts: A Cooperative Effect between Weak Acid and Base Sites

Cited by 126 publications

References 11 publications

Surface Base Sites of MgO Covered with Al2O3: XANES Analysis of Al and Mg K-edges

Surface Base Sites of MgO Covered with Al2O3: XANES Analysis of Al and Mg K-edges

Mechanistic studies of aldol condensations in UiO-66 and UiO-66-NH 2 metal organic frameworks

Aldol Condensations Using Bio-oil Model Compounds: The Role of Acid–Base Bi-functionality

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