Palladium/Carbon Catalyzed Hydrogen Transfer Reactions using Magnesium/Water as Hydrogen Donor
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Palladium/Carbon Catalyzed Hydrogen Transfer Reactions using Magnesium/Water as Hydrogen Donor Omari Muhammad Æ Sachin U. Sonavane Æ Yoel Sasson Æ Mandan Chidambaram
Received: 27 March 2008 / Accepted: 1 May 2008 / Published online: 3 June 2008 Ó Springer Science+Business Media, LLC 2008
Abstract A new methodology is developed for the hydrogenation reaction using magnesium/water system, as hydrogen source under catalytic palladium on activated carbon (Pd/C). The method is highly efficient for the chemoselective reduction of wide range of unsaturated aldehydes and ketones. The process is also found to be suitable when we think about green chemistry for the ecofriendly hydro-dehalogenation of aromatics. From practical point of view this new methodology is the most attractive, efficient, economical and convenient approach towards industrially important reduction transformations. This report is intended to highlight the use of Mg/H2O system in these organic transformations which can be easily adopted in industrial scale for the bulk production of hydrogenation products. Keywords Palladium/Carbon Magnesium/Water Hydrogenation Hydro-dehalogenation Deutero-dehalogenation
chemistry include selections of feedstock’s, reagents, solvents, reaction conditions, catalysts and the design of safer chemicals for safe and cheap practical methodologies. On the other hand, alternative reagents are also the focus of attention in green chemistry circle. The efficient catalytic reduction of water for generation of hydrogen is one of the most challenging transformations in chemistry [1]. Water is the ultimate hydrogen source, being both safe and plentiful. Recently few researchers reported the hydrogenation using H2O or D2O as a hydrogen source [2]. Hydrogen gas, in addition to its potential as an eco-friendly energy carrier, is one of the fundamental feed stocks in the contemporary chemical industries [3]. It has been long known that magnesium in methanol or in ethyl or isopropyl alcohol can be used for the reduction of various functional groups [4]. Utility of Mg/MeOH as an electron transfer reagent has appeared in literature rather sporadically since the ability of Mg/MeOH to reduce functional groups such as nitro, oxime, ketone and halogen was first discovered by Zechmeister [5].
1 Introduction
Mg + 2MeOH ! Mg (OMe)2 + H2
In recent years, green chemistry has received increased attention. The general areas of investigation in green
There after its use has been expanded not only to the selective reduction of various functional groups, but also to the reduction of conjugated double and triple bonds tethered to diverse functional groups such as esters [6], nitriles [7], amides [8] and aromatics [9] to the corresponding saturated analogs. Mg/MeOH has been demonstrated as a convenient single electron transfer reagent for a number of reductive reactions [10]. From environmental point of view, Mg/H2O is preferred methodology that can supersede the well-known limitations of catalytic hydrogenation using molecular hydrogen and hig
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