Nanocrystalline Magnesium Oxide as a Versatile Heterogeneous Catalyst for the Meerwein–Ponndorf–Verley Reduction of Cyclohexanone into Cyclohexanol: Effect of Preparation Method of Magnesium Oxide on Yield Hannaneh Heidari Æ Mansour Abedini Æ Ali Nemati Æ Mostafa M. Amini Received: 26 December 2008 / Accepted: 29 January 2009 Ó Springer Science+Business Media, LLC 2009 Abstract The Meerwein–Ponndorf–Verley (MPV) reac- tion of cyclohexanone with 2-propanol in the liquid phase in the presence of two different nanocrystalline magnesium oxides, prepared by different methods, was investigated. The catalyst consisting of nanocrystalline magnesium oxide, which was prepared by calcination of magnesium methoxide in air at 400 °C, showed the highest activity in the conversion of cyclohexanone to cyclohexanol with 97% yield. The effect of calcination temperature of mag- nesium oxide on the cyclohexanol yield and reusability of the catalyst has been studied. Keywords Nanocrystalline Á Magnesium oxide Á Basic catalyst Á Meerwein–Ponndorf–Verley Á Cyclohexanol 1 Introduction The Meerwein–Ponndorf–Verley (MPV) reduction is a con- venient route for the preparation of saturated and a, b-unsaturated alcohols, which can be used as starting mate- rials for the production of fine chemicals [1]. In recent years, development of asymmetric synthesis based on the MPV reduction has also been accelerated [2]. The MPV reaction involves the catalytic transfer of hydrogen atom from a sec- ondary alcohol, in general and 2-propanol, in particular, to a carbonyl compound. Metal alkoxides are generally used as catalysts for the MPV reaction [3], and to obtain acceptable yields, metal alkoxide must be used in a large excess, which makes the removal and separation process rather difficult leaving aside the economical and environmental concerns. Attempts have been made by several authors to use alternative catalysts for the MPV reaction such as trimethylaluminum, dimethylaluminum chloride [4], iridium [5], ruthenium [6], plutonium [7], samarium [8] complexes, and bimetallic alk- oxides [9] in homogenous systems. In spite of the advantage of the aforementioned metal complexes in MPV reactions, the separation and recovery of catalysts at the end of the process are difficult. To this end, heterogeneous catalysts for this reaction such as Al-free Zr-zeolite [10], supported zirconium propoxide [11], and MCM-41-grafted aluminum isopropox- ide [12] have been developed. However, preparations of the majority of those catalysts are highly labor-intensive in con- trast to metal oxides, which can be readily prepared. In this context, several authors have used metal oxides such as Al 2 O 3 [13], hydrous ZrO 2 [14], and MgO [15] in addition to Mg–Al mixed oxide [16] for MPV reaction. The Mg–Al mixed oxide is particularly interesting and the high activity of this catalyst is attributed to the presence of both basic and acidic sites [17]. Armendia et al. [18] showed that the Mg–Al mixed oxide prepared from the layered double hydroxides with an Mg/Al ratio of 2:1 and calcined at 500 °C shows the best catalytic activity in the reduction of cyclohexanone to cyclohexanol in the liquid phase by hydrogen transfer from 2-propanol. Interestingly, Kumbhar et al. [17] found that Mg–Al hydro- talcite with an Mg/Al ratio of 3:1 is a highly active and selective catalyst for the MPV reduction of 4-tert-butyl cyclohexanone. Considering that the number of acidic and basic sites can be influenced by the Mg/Al ratio and calcina- tion temperature [18], and both acidic and basic sites can catalyze the MPV reduction, such a contradictory result is not H. Heidari Á M. Abedini Á A. Nemati School of Chemistry, University College of Science, University of Tehran, Tehran, Iran M. M. Amini (&) Department of Chemistry, Shahid Beheshti University, G.C., Tehran, Iran e-mail: m-pouramini@cc.sbu.ac.ir 123 Catal Lett DOI 10.1007/s10562-009-9885-2