- An ionic liquid catalyzed probase method for one-pot synthesis of α,β-unsaturated esters from esters and aldehydes under mild conditions
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A one-pot synthesis of α,β-unsaturated esters from unactivated esters and aldehydes using strong bases, such as sodium alkoxide and potassium tert-butoxide, was reported. However, the ionic liquid (IL) catalyzed probase method for producing α,β-unsaturated esters was not reported until now. In this work, a series of ILs with fluoride anions were firstly prepared and used as catalysts in combination with the probase N,O-bis(trimethylsilyl) acetamide (BSA) for the α,β-unsaturated esters synthesis. This process could also be promoted through the introduction of another IL with Lewis acid sites. The yield and selectivity of the product could reach up to 84.2% and 95.0%, respectively, when [Bmim]F was used in combination with [Bmim]Cl/AlCl3 (the molar fraction of AlCl3 is 0.67). The mechanism investigation through GC-MS indicates that BSA would convert into onium amide, which acted as a strong base for α-H abstraction, with the catalysis of [Bmim]F. Meanwhile, [Bmim]Cl/AlCl3 played an important role in the condensation step between enolates and aldehydes. On the basis of mechanism insights, kinetic and thermodynamic studies were also carried out for a better understanding of this new route.
- Wang, Gang,Xu, Yiming,Zhang, Suojiang,Li, Zengxi,Li, Chunshan
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p. 4838 - 4848
(2017/10/23)
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- Magnetically recyclable Pd/γ-AlOOH@Fe3O4 catalysts and their catalytic performance for the Heck coupling reaction
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Novel magnetically recyclable Pd/γ-AlOOH@Fe3O4 catalysts were prepared using γ-AlOOH@Fe3O4 as a magnetic supporter and nano-Pd particles as the active catalytic component. The structure of the catalysts was characterized by XRD (X-ray diffraction), TEM (transmission electron microscopy), N2 adsorption-desorption, and a VSM (vibration sample magnetometer). The catalytic activity and recyclability for the Heck coupling reaction were investigated. Results showed that the magnetic γ-AlOOH@Fe3O4 possessed a core-shell structure, as well as that the nano-Pd particles were 6-8 nm and had been well dispersed in the γ-AlOOH shell. In the Heck coupling reactions, the magnetic Pd/γ-AlOOH@Fe3O4 catalysts exhibited good catalytic activity and recyclability. For the (0.021 mol%)Pd/γ- AlOOH@Fe3O4 catalyst, the bromobenzene conversion and product yield reached about 100% and 96.3%, respectively, under a 120°C reaction temperature and 12 h reaction time. After being recycled 8 times, the conversion of bromobenzene and the recovery of the catalyst were about 90% and 93%, respectively. The nano-Pd particles were kept well dispersed in the used Pd/γ-AlOOH@Fe3O4 catalyst.
- Yang, Hao,Ji, Shengfu,Liu, Xuefei,Zhang, Danni,Shi, Da
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p. 866 - 872
(2014/06/24)
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- Syntheses and QSAR studies of sorbic, cinnamic and ricinoleic acid derivatives as potential antibacterial agents
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Amides and esters of sorbic, cinnamic and ricinoleic acid have been synthesized and evaluated for their antibacterial activity against gram (+) ve S. aureus, B. subtilis and gram (-) ve E. coli. Most of the compounds have shown moderate to good activity against microorganisms under test. Linear regression analysis of descriptors related to lipophilicity, steric and electronic parameters against antibacterial activity have been performed. QSAR studies indicated the predominance of electronic and steric parameters over the lipophilicity parameters in contributing antibacterial activity.
- Narasimhan,Kothawade,Pharande,Mourya,Dhake
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p. 2828 - 2834
(2007/10/03)
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