Effect of acetone/citral molar ratio and reaction conditions in the aldol condensation of citral with acetone catalyzed by a Mg,Al-mixed oxide

Pérez, Carlos André de Castro; Henriques, Cristiane A.; Antunes, Octávio Augusto Ceva; Monteiro, J.L.F.

doi:10.1016/j.molcata.2005.02.001

Cited by 17 publications

(9 citation statements)

References 15 publications

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“…Compared with the results reported, , the bands of all carbonate species shift to a higher wavenumber, probably due to the introduction of rare earth elements in the lattice of hydrotalcite. The following base strength order for these surface oxygen species were also determined: low coordination O 2– anions > oxygen in Mn + –O 2– pairs > OH groups …”

Section: Resultscontrasting

confidence: 84%

“…The third adsorbed species is an unidentate carbonate, which requires isolated surface O 2– ions (low-coordination anions, such as those located at corners or edges) and exhibits a symmetric O–C–O stretching at 1540 cm –1 and an asymmetric O–C–O stretching at 1630 cm –1 . Compared with the results reported, , the bands of all carbonate species shift to a higher wavenumber, probably due to the introduction of rare earth elements in the lattice of hydrotalcite. The following base strength order for these surface oxygen species were also determined: low coordination O 2– anions > oxygen in Mn + –O 2– pairs > OH groups …”

Section: Resultsmentioning

confidence: 59%

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Effect of One-Pot Rehydration Process on Surface Basicity and Catalytic Activity of Mg_yAl_1-aREE_aO_x Catalyst for Aldol Condensation of Citral and Acetone

Wang

Guo

et al. 2016

ACS Sustainable Chem. Eng.

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The liquid phase synthesis of pseudoionones (PS) by the cross-aldol condensation of citral and acetone was investigated over MgAl mixed oxides containing rare earth elements (REE = Y, La, Eu), which were obtained from corresponding REE-modified hydrotalcite materials after calcination. The results showed that the unmodified and La(Eu)-modified MgAl mixed oxide catalysts showed relatively low activity, and Y-modified MgAl mixed oxides presented an unexpected high catalytic activity. PS selectivity of ∼85% and citral conversion of 100% were achieved at 60 °C for 3 h. On the basis of the characterizations of the structural, textural, and basic properties, it was found that Mg3Al1‑aYaO x catalysts exhibited relatively well-developed small flake morphology with high surface area and pore volume, resulting in exposure of more basic sites on the catalyst surface. The formation of PS over Mg3Al1‑aYaO x may be accompanied by gradual modification of the catalyst surface to form re-Mg3Al1‑aYaO x through a rehydration process with produced water, which reconverts the O2– basic sites to OH– basic groups. Unlike La and Eu elements, the presence of Y could promote this “one-pot” or in situ rehydration process of MgAl mixed oxides during the aldol reaction. This Y-modified MgAl mixed oxides after a one-pot rehydration process with active Brønsted basic sites is responsible for the high activity in the cross-aldol condensation of citral and acetone.

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Section: Resultscontrasting

confidence: 84%

Section: Resultsmentioning

confidence: 59%

Effect of One-Pot Rehydration Process on Surface Basicity and Catalytic Activity of Mg_yAl_1-aREE_aO_x Catalyst for Aldol Condensation of Citral and Acetone

Wang

Guo

et al. 2016

ACS Sustainable Chem. Eng.

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“…Then, the mixture was stirred under 318 K for 24 h, aged at 373 K for 24 h under static conditions, and then the product filtered, thoroughly washed, dried, and calcined as for the preparation of the Al-SBA-15 sample [20]. The molar composition of the mixture, TEOS/ P123/Al(NO 3 …”

Section: Synthesis Of Al-containing Mesoporous Sba-15mentioning

confidence: 99%

“…The product of an aldol condensation can dehydrate to form an a,b-unsaturated carbonyl compound under either acidic or basic conditions. Hence, both the aldol condensation and the dehydration are capable of being catalyzed by conventional monofunctional catalysts that possess either acidic or basic centers [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Optimizing the matching between the acid and the base of cooperative catalysis to inhibit dehydration in the aldol condensation

Liu

et al. 2011

Journal of Colloid and Interface Science

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“…The molar ratio between valeraldehyde and cyclopentanone also played an important role in the selectivity between cross-and self-condensation 3,7,9,16 . Entries 1-6 (Table-1) showed that valeraldehyde/cyclopentanone molar ratio of 1/5 was the optimal reaction condition.…”

Section: Resultsmentioning

confidence: 99%

A Highly Selective Aldol Condensation of Cyclopentanone with Valeraldehyde Over Hydrotalcite-type Catalysts

Xu¹,

Cao²,

Ma³

et al. 2013

Asian J. Chem.

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The aldol condensation using cyclopentanone with valeraldehyde was conducted at hydrotalcites catalysis. The catalyst was obtained by calcining the hydrotalcite precursor (Mg/Al = 3:1) at 773 K. Its reaction performance was evaluated on the various molar ratios of cyclopentanone to n-valeraldehyde. A good catalytic selectivity of 90 % and a high conversion of 93 % were achieved under mild conditions.

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Effect of acetone/citral molar ratio and reaction conditions in the aldol condensation of citral with acetone catalyzed by a Mg,Al-mixed oxide

Cited by 17 publications

References 15 publications

Effect of One-Pot Rehydration Process on Surface Basicity and Catalytic Activity of Mg_yAl_1-aREE_aO_x Catalyst for Aldol Condensation of Citral and Acetone

Effect of One-Pot Rehydration Process on Surface Basicity and Catalytic Activity of Mg_yAl_1-aREE_aO_x Catalyst for Aldol Condensation of Citral and Acetone

Optimizing the matching between the acid and the base of cooperative catalysis to inhibit dehydration in the aldol condensation

A Highly Selective Aldol Condensation of Cyclopentanone with Valeraldehyde Over Hydrotalcite-type Catalysts

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Effect of acetone/citral molar ratio and reaction conditions in the aldol condensation of citral with acetone catalyzed by a Mg,Al-mixed oxide

Cited by 17 publications

References 15 publications

Effect of One-Pot Rehydration Process on Surface Basicity and Catalytic Activity of MgyAl1-aREEaOx Catalyst for Aldol Condensation of Citral and Acetone

Effect of One-Pot Rehydration Process on Surface Basicity and Catalytic Activity of MgyAl1-aREEaOx Catalyst for Aldol Condensation of Citral and Acetone

Optimizing the matching between the acid and the base of cooperative catalysis to inhibit dehydration in the aldol condensation

A Highly Selective Aldol Condensation of Cyclopentanone with Valeraldehyde Over Hydrotalcite-type Catalysts

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Effect of One-Pot Rehydration Process on Surface Basicity and Catalytic Activity of Mg_yAl_1-aREE_aO_x Catalyst for Aldol Condensation of Citral and Acetone

Effect of One-Pot Rehydration Process on Surface Basicity and Catalytic Activity of Mg_yAl_1-aREE_aO_x Catalyst for Aldol Condensation of Citral and Acetone