Aldol Condensation of Benzaldehyde and Heptanal Over Zinc Modified Mixed Mg/Al Oxides

Tišler, Zdeněk; Vrbková, Eva; Kocík, Jaroslav; Kadlec, David; Vyskočilová, Eliška; Červený, Libor

doi:10.1007/s10562-018-2416-2

Cited by 9 publications

(9 citation statements)

References 28 publications

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“…By increasing the formation of jasminaldehyde and 2-n-pentyl-2-n-nonenal after 32 h of reaction, the formation of other products slightly decreased. Improvement of heptanal conversion and jasminaldehyde selectivity by increasing the reaction temperature was also reported by other researchers [4,5,10,30], which is in line with the results obtained in the current study. Aldol condensation of benzaldehyde with heptanal using the zinc- (Figure 5b), after 10 h of reaction, conversion of heptanal significantly increased to about 80%, which is about 2.5 times higher than the conversion at 100 • C, at same reaction time.…”

Section: Catalytic Performance For the Aldol Condensation Reactionsupporting

confidence: 93%

“…The total basicity of the sample was found to be 1193 µmol/g, where the concentration of the weak, medium, and strong basic sites were 22.8%, 50.0%, and 27.2% of total basicity respectively. It has been reported that the higher basic sites with medium and strong strength could be beneficial for aldol condensation of benzaldehyde with heptanal [5]; therefore, the active basic sites in this reaction are mainly M n+ − O 2− pairs.…”

Section: Catalyst Characterizationmentioning

confidence: 98%

“…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%

“…In general, because of its monobasic property and the low selectivity to jasminaldehyde, magnesium oxide is not an appropriate catalyst for the synthesis of In the conventional industrial process, homogeneous inorganic hydroxides such as NaOH and KOH are used for the production of jasminaldehyde. However, the use of theses homogeneous hydroxide-based catalysts has several drawbacks, such as lack of reusability of catalyst, employing a corrosive mixtures, formation of a large amount of liquid waste, separation and disposal of effluent containing sodium or potassium hydroxides [3,5,[12][13][14]. Thus, it is necessary to develop solid base heterogeneous catalysts for the synthesis of jasminaldehyde to provide an industrial process with easy product separation, lower corrosion of the reactor, the possibility of regeneration and reuse of catalysts, and the formation of the product with higher selectivity to jasminaldehyde.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the presence of solvent could decrease the possibility of adsorption of reactant molecules. Later, the same research group [5], studied the synthesis of jasminaldehyde over the zinc modified Mg-Al mixed oxide at 80-120 • C, 7 h, and the benzaldehyde to heptanal mole ratio of 2. Comparison of the activity of Mg-Al oxide and the zinc-modified Mg-Al oxides catalysts under the same reaction conditions revealed that the zinc-modified Mg-Al catalysts yielding 15-20% higher jasminaldehyde than Mg-Al catalyst.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Catalytic Performance For the Aldol Condensation Reactionsupporting

confidence: 93%

Section: Catalyst Characterizationmentioning

confidence: 98%