Direct synthesis of p-methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanism
Summary: p-Methyl benzaldehyde (p-MBA) is a class of key chemical intermediates of pharmaceuticals. Conventional industrial processes for p-MBA production involve the consecutive photochlorination, amination, and acid hydrolysis of petroleum-derived p-xylene, while producing vast pollutants and wast...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2021-09-01
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| Series: | iScience |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2589004221009962 |
| _version_ | 1818728966238765056 |
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| author | Qing-Nan Wang Xianghui Liu Kai Wang Yan Liu Sheng-Mei Lu Can Li |
| author_facet | Qing-Nan Wang Xianghui Liu Kai Wang Yan Liu Sheng-Mei Lu Can Li |
| author_sort | Qing-Nan Wang |
| collection | DOAJ |
| description | Summary: p-Methyl benzaldehyde (p-MBA) is a class of key chemical intermediates of pharmaceuticals. Conventional industrial processes for p-MBA production involve the consecutive photochlorination, amination, and acid hydrolysis of petroleum-derived p-xylene, while producing vast pollutants and waste water. Herein, we report a direct, green route for selective synthesis of p-MBA from acetaldehyde using a diphenyl prolinol trimethylsilyl ether catalyst. The optimized p-MBA selectivity is up to 90% at an acetaldehyde conversion as high as 99.8%. Intermediate structure and 18O-isotope data revealed that the conversion of acetaldehyde to p-methylcyclohexadienal intermediates proceeds in an enamine-iminium intermediate mechanism. Then, controlled experiments and D-isotope results indicated that the dehydrogenation of p-methylcyclohexadienal to p-MBA and H2 is catalyzed by the same amines through an iminium intermediate. This is an example that metal-free amines catalyze the dehydrogenation (releasing H2), rather than using metals or stoichiometric oxidants. |
| first_indexed | 2024-12-17T22:38:23Z |
| format | Article |
| id | doaj.art-3e13b2cb6d084156bbd499595db63457 |
| institution | Directory Open Access Journal |
| issn | 2589-0042 |
| language | English |
| last_indexed | 2024-12-17T22:38:23Z |
| publishDate | 2021-09-01 |
| publisher | Elsevier |
| record_format | Article |
| series | iScience |
| spelling | doaj.art-3e13b2cb6d084156bbd499595db634572022-12-21T21:30:02ZengElsevieriScience2589-00422021-09-01249103028Direct synthesis of p-methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanismQing-Nan Wang0Xianghui Liu1Kai Wang2Yan Liu3Sheng-Mei Lu4Can Li5State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, ChinaState Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, ChinaState Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, ChinaState Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, ChinaState Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, ChinaState Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; Corresponding authorSummary: p-Methyl benzaldehyde (p-MBA) is a class of key chemical intermediates of pharmaceuticals. Conventional industrial processes for p-MBA production involve the consecutive photochlorination, amination, and acid hydrolysis of petroleum-derived p-xylene, while producing vast pollutants and waste water. Herein, we report a direct, green route for selective synthesis of p-MBA from acetaldehyde using a diphenyl prolinol trimethylsilyl ether catalyst. The optimized p-MBA selectivity is up to 90% at an acetaldehyde conversion as high as 99.8%. Intermediate structure and 18O-isotope data revealed that the conversion of acetaldehyde to p-methylcyclohexadienal intermediates proceeds in an enamine-iminium intermediate mechanism. Then, controlled experiments and D-isotope results indicated that the dehydrogenation of p-methylcyclohexadienal to p-MBA and H2 is catalyzed by the same amines through an iminium intermediate. This is an example that metal-free amines catalyze the dehydrogenation (releasing H2), rather than using metals or stoichiometric oxidants.http://www.sciencedirect.com/science/article/pii/S2589004221009962ChemistryCatalysisOrganic chemistryOrganic synthesis |
| spellingShingle | Qing-Nan Wang Xianghui Liu Kai Wang Yan Liu Sheng-Mei Lu Can Li Direct synthesis of p-methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanism iScience Chemistry Catalysis Organic chemistry Organic synthesis |
| title | Direct synthesis of p-methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanism |
| title_full | Direct synthesis of p-methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanism |
| title_fullStr | Direct synthesis of p-methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanism |
| title_full_unstemmed | Direct synthesis of p-methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanism |
| title_short | Direct synthesis of p-methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanism |
| title_sort | direct synthesis of p methyl benzaldehyde from acetaldehyde via an organic amine catalyzed dehydrogenation mechanism |
| topic | Chemistry Catalysis Organic chemistry Organic synthesis |
| url | http://www.sciencedirect.com/science/article/pii/S2589004221009962 |
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