- Pyridinium saccharinate salts as efficient recyclable acylation catalyst: A new bridge between heterogeneous and homogeneous catalysis
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It is important to find a way for separation of concerned chemicals from product mixture after reaction, in order to avoid spreading harmful chemicals to society. The homogeneous nature of DMAP-catalyzed acylation still suffers from the problems of catalyst separation and/or residual DMAP contamination. DMAP causes acute dermal toxicity, whereas the corresponding DMAP salt exhibits only slight irritation to the skin. Very recently, we found that the DMAP saccharinate salt is also great recyclable catalyst, whose acylation of alcohols has been successfully and effectively carried out 10 times without loss in activity. This report covers our comprehensive studies on using the pyridinium saccharinate salts as efficient recyclable acylation catalysts including 4-N,N-dimethylaminopyridinium saccharinate (A), 4-(1-pyrrolidinyl) pyridinium saccharinate (B), 2-N,N-dimethylaminopyridinium saccharinate (C), and pyridinium saccharinate (D). Their structure and reactivity have been studied. The salts A, C, and D contain very interesting seven-membered synthon showing multiple H-bonding interactions for pair of pyridinium cation and saccharinate anion in the solid state. The salt B exhibits H-bonding interaction of N(sac) ... H-N(py) in the solid state, instead of seven-membered synthon. The catalytic reactivity studies show that salts A and B are both very effective, with salt B even better in reactivity, and are both recyclable in the esterification of a variety of alcohols, under solvent-free and base-free conditions at room temperature.
- Lu, Norman,Chang, Wei-Hsuan,Wei, Rong-Jyun,Fang, Yung-Cheng,Han, Tu-Wen,Wang, Guo-Quan,Chang, Jia-Yaw,Wen, Yuh-Sheng,Liu, Ling-Kang
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p. 3468 - 3476
(2016/06/06)
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- RECYCLABLE CATALYSTS FOR ESTERIFICATION OR ACYLATION OF ALCOHOLS
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A compound is useful as a recyclable catalyst for esterification or acylation of alcohols and consists of saccharine and a compound comprising a pyridine moiety. In addition, also a method of preparing the compound and an ester synthesis method using the compound are introduced.
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Page/Page column 4
(2012/07/28)
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- A salt made of 4-N,N-dimethylaminopyridine (DMAP) and saccharin as an efficient recyclable acylation catalyst: A new bridge between heterogeneous and homogeneous catalysis
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Here, we report insights into the new recyclable catalyst 1, (DMAP·saccharin). The DMAP·saccharin-catalysed acylation of alcohols has been successfully carried out more than 8 times. Only 1 mol% of catalyst 1 efficiently promotes acylation with almost equimolar amounts of acid anhydrides, under both base-free and solvent-free conditions.
- Lu, Norman,Chang, Wei-Hsuan,Tu, Wen-Han,Li, Chieh-Keng
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supporting information; experimental part
p. 7227 - 7229
(2011/09/12)
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- Widely useful DMAP-catalyzed esterification under auxiliary base- and solvent-free conditions
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With regard to atom economy and E-factor, catalytic condensation of carboxylic acids with equimolar amounts of alcohols is the most desirable. Although several highly active dehydration catalysts have been reported, more efficient alternatives are still strongly needed because the dehydrative esterification of tertiary alcohols, phenols, acid-sensitive alcohols, amino acids, and hardly soluble alcohols has never proceeded satisfactorily. Here we report new insights into the classical DMAP-catalyzed acylation of alcohols: surprisingly, only a 0.05-2 mol % of DMAP can efficiently promote acylation of alcohols with acid anhydrides under auxiliary base- and solvent-free conditions to give the corresponding esters in high yields. Furthermore, we achieved the recovery and reuse of commercially available polystyrene-supported DMAP without using any solvents. These serendipitous findings provide widely useful and environmentally benign esterification methods, which might be more practical and reliable than catalytic dehydrative condensation methods, in particular, for the less reactive alcohols which hardly condense with carboxylic acid directly.
- Sakakura, Akira,Kawajiri, Kimio,Ohkubo, Takuro,Kosugi, Yuji,Ishihara, Kazuaki
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p. 14775 - 14779
(2008/09/17)
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- FACILE METHOD FOR THE ACYLATION OF ALCOHOLS AND AMIDES BY THE USE OF 1,1'-DIMETHYLSTANNOCENE AND ACYL CHLORIDES
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Acylation of alcohols and amides was effected under mild conditions by the use of 1,1'-dimethylstannocene and acyl chlorides, giving the corresponding esters and imides in good to excellent yields.
- Mukaiyama, Teruaki,Ichikawa, Junji,Asami, Masatoshi
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p. 293 - 296
(2007/10/02)
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