Potassium modified alumina as a catalyst for the aldol condensation of benzaldehyde with linear C3–C8 aldehydes

Vrbková, Eva; Vyskočilová, Eliška; Červený, Libor

doi:10.1007/s11144-017-1150-x

Cited by 12 publications

(7 citation statements)

References 19 publications

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“…16 Modification of zeolites by caesium ions was also performed using the impregnation method, again using caesium acetate. 14…”

Section: Methodsmentioning

confidence: 99%

“…5,6 The use of different heterogeneous catalysts can offer the possibility of catalyst reuse or at least simple separation of catalysts. A large number of heterogeneous catalysts have already been used in different aldol condensations—for example, silanol-modified mesoporous materials, 7,8 acid-modified silicas 9,10 , hydrotalcites and mixed oxides, 6,11–13 materials modified with caesium or potassium, 14 or magnesium organosilicates. 15 In the present study, the aldol condensation of heptanal with cyclopentanone was chosen to compare the activity of different types of heterogeneous catalyst.…”

Section: Introductionmentioning

confidence: 99%

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Heterogeneous catalysts in the aldol condensation of heptanal with cyclopentanone

Vrbková

Kovářová

Vyskočilová

et al. 2019

Progress in Reaction Kinetics and Mechanism

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A large number of heterogeneous catalysts were tested in the aldol condensation of heptanal with cyclopentanone. There are many possible products from this aldol condensation, among which the most desired is 2-heptylidenecyclopentanone. As heterogeneous catalysts, the following were tested: caesium modified zeolites, functionalized MCM-41, and single (MgO, CaO, ZnO) and double (Mo–Si, Mg–Al, Zn–Al) metal oxides. The activity of modified zeolites and functionalized zeolites in this aldol condensation was low, whereas single and double metal oxides possessed high activity. The highest selectivity to the desired 2-heptylidenecyclopentanone (52%) was obtained using magnesium oxide as catalyst.

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“…16 Modification of zeolites by caesium ions was also performed using the impregnation method, again using caesium acetate. 14…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Heterogeneous catalysts in the aldol condensation of heptanal with cyclopentanone

Vrbková

Kovářová

Vyskočilová

et al. 2019

Progress in Reaction Kinetics and Mechanism

Self Cite

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“…Aldol condensation and transesterification, are two examples of the most practical reactions in industry, especially in the field of fuel and energy, which are usually catalyzed by a basic reagent in the presence of a catalyst. [ 1 , 2 , 3 , 4 ] Aldol condensation has a wide range of application in fine chemicals synthesis; and includes two steps: [5] (i) the intermediate formation of enols by a basic reagent, and (ii) the formation of a C−C bond between the enols and the carbonyl group that can be takes place via the reaction of an adsorbed molecule and a molecule in the fluid (Ely‐Rideal model) or occurs through a two‐molecular surface reaction (Langmuir‐Hinshelwood model) for heterogeneous catalysts. [6] The next two steps of the re‐protonation and dehydration lead to the desired product.…”

Section: Introductionmentioning

confidence: 99%

Metal‐ and Solvent‐Free Transesterification and Aldol Condensation Reactions by a Homogenous Recyclable Basic Ionic Liquid Based on the 1,3,5‐Triazine Framework

Ren

Kazemnejadi

2021

ChemistryOpen

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A new recyclable basic ionic liquid was introduced as an efficient catalyst for aldol condensation and transesterification reactions under environmentally friendly conditions. The catalyst was prepared based on methyl imidazolium moieties bearing hydroxide counter anions via the Hofmann elimination on a 1,3,5‐triazine framework. The ionic liquid with two functionalities including anion stabilizer and high basicity, was used as an efficient catalyst for aldol condensation as well as transesterification reaction of a variety of alkyl benzoates. All reactions were performed in the absence of any external reagent, co‐catalyst, or solvent, in line with environmental protection. The kinetics isotope effect (KIE) was conducted for the transesterification reaction to elucidate the mechanism and rate determining step (RDS). It worth noted that, the homogeneous catalyst could be recycled from the reaction mixture and reused for several consecutive runs with insignificant drop of basicity and conversion.

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“…Owing to the lower price of synthetic materials, their higher stability in acidic, basic, and even oxidizing media, these compounds became more attractive to be used in the synthesis of perfumery chemicals [2]. Jasminaldehyde can be synthesized via the cross aldol condensation of heptanal (C 7 H 14 O) and benzaldehyde (C 7 H 6 O) (Scheme 1), and this process has been intensively studied by researchers to enhance the yield of jasminaldehyde [3][4][5][6][7][8][9][10]. In addition to jasminaldehyde, the self-condensation of heptanal resulted in the formation of 2-n-pentyl-2-n-nonenal (C 14 H 26 O) as the main by-product of this reaction.…”

Section: Introductionmentioning

confidence: 99%

“…Vrbková et al [6] synthesized several layered double hydrotalcite catalysts, with the Mg/Al molar ratio of 2.0 to 4.0, and their activity in aldol condensation reaction was investigated. After 4 h of reaction, conversion of at least 90% was achieved with all catalysts, however, in general, catalysts with Mg/Al ratio of 3 and 4 showed higher activity and selectivity in the solvent-free reaction at 100 • C, and benzaldehyde to heptanal ration of 2.…”

Section: Introductionmentioning

confidence: 99%

Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide

et al. 2020

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In spite of the rapid developments in synthesis methodologies in different fields, the traditional methods are still used for the synthesis of organic compounds, and regardless of the type of chemistry, these reactions are typically performed in standardized glassware. The high-throughput chemical synthesis of organic compounds such as fragrant molecules, with more economic benefits, is of interest to investigate and develop a process that is more economical and industrially favorable. In this research, the catalytic activity of Mg-Al catalyst derived from hydrotalcite-like precursors with the Mg/Al molar ratio of 3 was investigated for the solvent-free synthesis of jasminaldehyde via aldol condensation of benzaldehyde and heptanal. The reaction was carried out in a fixed-bed flow reactor, at 1 MPa, and at different temperatures. Both Brønsted and Lewis (O2− anions) base sites, and Lewis acid sites exist on the surface of the Mg-Al catalyst, which can improve the catalytic performance. Increasing the reaction temperature from 100 °C to 140 °C enhanced both heptanal conversion and selectivity to jasminaldehyde. After 78 h of reaction at 140 °C, the selectivity to jasminaldehyde reached 41% at the heptanal conversion 36%. Self-condensation of heptanal also resulted in the formation of 2-n-pentyl-2-n-nonenal. The presence of weak Lewis acid sites creates a positive charge on the carbonyl group of benzaldehyde, and makes it more prone to attack by the carbanion of heptanal. Heptanal, is an aliphatic aldehyde, with higher activity than benzaldehyde. Therefore, the possibility of activated heptanal reacting with other heptanal molecules is higher than its reaction with the positively charged benzaldehyde molecule, especially at a low molar ratio of benzaldehyde to heptanal.

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Potassium modified alumina as a catalyst for the aldol condensation of benzaldehyde with linear C3–C8 aldehydes

Cited by 12 publications

References 19 publications

Heterogeneous catalysts in the aldol condensation of heptanal with cyclopentanone

Heterogeneous catalysts in the aldol condensation of heptanal with cyclopentanone

Metal‐ and Solvent‐Free Transesterification and Aldol Condensation Reactions by a Homogenous Recyclable Basic Ionic Liquid Based on the 1,3,5‐Triazine Framework

Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide

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