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	Epoxidation of alpha,beta-unsaturated acids catalyzed by tungstate (VI) or molybdate (VI) in aqueous solvents: a specific direct oxygen transfer mechanism
	Shi, H ; Wang, X ; Hua, RM ; Zhang, Z ; Tang, H
	2010-05-06 ; 2010-05-06
关键词	alpha,beta-unsaturated acid cis-1-propenylphosphonic acid epoxidation mechanism diperoxocomplex OLEFIN EPOXIDATION HYDROGEN-PEROXIDE MOLYBDENUM COMPLEXES OXIDATIONS ACTIVATION KINETICS METALS MODEL H2O Chemistry, Organic
中文摘要	The epoxidation mechanism of alpha,beta-unsaturated acids catalyzed by Na2WO4 or Na2MoO4 in aqueous solvents has been studied by means of kinetic experiments, MS, P-31 NMR and C-13 NMR. The results show Na2WO4 or Na2MoO4 and H2O2 can rapidly form the diperoxocomplex irreversibly in aqueous solvent. P-31 NMR and kinetics study reveal that -P=O in cis-1-propenylphosphonic acid (CPPA) can fast coordinate to the metal center (Mo or W) of the diperoxocomplex irreversibly to form a stable complex. The subsequent direct oxygen transfer from peroxo bond to double bond is a monomolecular process, thus the epoxidation is zero-order on CPPA. However, C-13 NMR shows the -C=O in alpha,beta-unsaturated carboxylic acids cannot coordinate to metal center of the diperoxocomplex. Therefore, the oxygen transfer is a bimolecular process and the epoxidation is a first-order reaction on the acids. In the mechanism, the nucleophilic attack of double bond towards the peroxo bond is regarded as through a spiro-transition structure. (C) 2004 Elsevier Ltd. All rights reserved.
语种	英语 ; 英语
出版者	PERGAMON-ELSEVIER SCIENCE LTD ; OXFORD ; THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND
内容类型	期刊论文
源URL	[http://hdl.handle.net/123456789/12262]
专题	清华大学
推荐引用方式 GB/T 7714	Shi, H,Wang, X,Hua, RM,et al. Epoxidation of alpha,beta-unsaturated acids catalyzed by tungstate (VI) or molybdate (VI) in aqueous solvents: a specific direct oxygen transfer mechanism[J],2010, 2010.
APA	Shi, H,Wang, X,Hua, RM,Zhang, Z,&Tang, H.(2010).Epoxidation of alpha,beta-unsaturated acids catalyzed by tungstate (VI) or molybdate (VI) in aqueous solvents: a specific direct oxygen transfer mechanism..
MLA	Shi, H,et al."Epoxidation of alpha,beta-unsaturated acids catalyzed by tungstate (VI) or molybdate (VI) in aqueous solvents: a specific direct oxygen transfer mechanism".(2010).

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