Mechanism of MTO-Catalyzed Deoxydehydration of Diols to Alkenes Using Sacrificial Alcohols

详细信息    查看全文

• 作者：Shuo Liu ; Aysegul Senocak ; Jessica L. Smeltz ; Linan Yang ; Benjamin Wegenhart ; Jing Yi ; Hilkka I. Kentt盲maa ; Elon A. Ison ; Mahdi M. Abu-Omar
• 刊名：Organometallics
• 出版年：2013
• 出版时间：June 10, 2013
• 年：2013
• 卷：32
• 期：11
• 页码：3210-3219
• 全文大小：673K
• 年卷期：v.32,no.11(June 10, 2013)
• ISSN：1520-6041

文摘

Catalytic deoxydehydration (DODH) of vicinal diols is carried out employing methyltrioxorhenium (MTO) as the catalyst and a sacrificial alcohol as the reducing agent. The reaction kinetics feature an induction period when MTO is added last and show zero-order in [diol] and half-order dependence on [catalyst]. The rate-determining step involves reaction with alcohol, as evidenced by a KIE of 1.4 and a large negative entropy of activation (螖S^{鈥?/sup> = 鈭?54 卤 33 J mol鈥? K鈥?). The active form of the catalyst is methyldioxorhenium(V) (MDO), which is formed by reduction of MTO by alcohol or via a novel C鈥揅 bond cleavage of an MTO-diolate complex. The majority of the MDO-diolate complex is present in dinuclear form, giving rise to the [Re]1/2 dependence. The MDO-diolate complex undergoes further reduction by alcohol in the rate-determining step to give rise to a putative rhenium(III) diolate. The latter is the active species in DODH extruding stereoselectively trans-stilbene from (R,R)-(+)-hydrobenzoin to regenerate MDO and complete the catalytic cycle.}