Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide
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 s...
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MDPI AG
2020-09-01
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| Series: | Catalysts |
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| Online Access: | https://www.mdpi.com/2073-4344/10/9/1033 |
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| author | Zahra Gholami Zdeněk Tišler Pavla Vondrová Romana Velvarská Kamil Štěpánek |
| author_facet | Zahra Gholami Zdeněk Tišler Pavla Vondrová Romana Velvarská Kamil Štěpánek |
| author_sort | Zahra Gholami |
| collection | DOAJ |
| description | 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 (<inline-formula><math display="inline"><semantics><mrow><msup><mi mathvariant="normal">O</mi><mrow><mn>2</mn><mo>−</mo></mrow></msup></mrow></semantics></math></inline-formula> 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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| institution | Directory Open Access Journal |
| issn | 2073-4344 |
| language | English |
| last_indexed | 2024-03-10T16:28:30Z |
| publishDate | 2020-09-01 |
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| series | Catalysts |
| spelling | doaj.art-4020ec30d81e46cbb0ebc791d3b36cce2023-11-20T13:01:24ZengMDPI AGCatalysts2073-43442020-09-01109103310.3390/catal10091033Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed OxideZahra Gholami0Zdeněk Tišler1Pavla Vondrová2Romana Velvarská3Kamil Štěpánek4Unipetrol Centre of Research and Education, a.s, Areál Chempark 2838, Záluží 1, 436 70 Litvínov, Czech RepublicUnipetrol Centre of Research and Education, a.s, Areál Chempark 2838, Záluží 1, 436 70 Litvínov, Czech RepublicUnipetrol Centre of Research and Education, a.s, Areál Chempark 2838, Záluží 1, 436 70 Litvínov, Czech RepublicUnipetrol Centre of Research and Education, a.s, Areál Chempark 2838, Záluží 1, 436 70 Litvínov, Czech RepublicUnipetrol Centre of Research and Education, a.s, Areál Chempark 2838, Záluží 1, 436 70 Litvínov, Czech RepublicIn 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 (<inline-formula><math display="inline"><semantics><mrow><msup><mi mathvariant="normal">O</mi><mrow><mn>2</mn><mo>−</mo></mrow></msup></mrow></semantics></math></inline-formula> 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.https://www.mdpi.com/2073-4344/10/9/1033Mg-Al hydrotalcitealdol condensationjasminaldehydebenzaldehydeheptanalfixed-bed flow reactor |
| spellingShingle | Zahra Gholami Zdeněk Tišler Pavla Vondrová Romana Velvarská Kamil Štěpánek Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide Catalysts Mg-Al hydrotalcite aldol condensation jasminaldehyde benzaldehyde heptanal fixed-bed flow reactor |
| title | Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide |
| title_full | Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide |
| title_fullStr | Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide |
| title_full_unstemmed | Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide |
| title_short | Solvent-Free Synthesis of Jasminaldehyde in a Fixed-Bed Flow Reactor over Mg-Al Mixed Oxide |
| title_sort | solvent free synthesis of jasminaldehyde in a fixed bed flow reactor over mg al mixed oxide |
| topic | Mg-Al hydrotalcite aldol condensation jasminaldehyde benzaldehyde heptanal fixed-bed flow reactor |
| url | https://www.mdpi.com/2073-4344/10/9/1033 |
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