Applied Catalysis A: General 392 (2011) 218–224 Contents lists available at ScienceDirect Applied Catalysis A: General journal homepage: www.elsevier.com/locate/apcata Copper on boehmite: A simple, selective, efficient and reusable heterogeneous catalyst for oxidation of alcohols with periodic acid in water at room temperature S. Ganesh Babu, P. Aruna Priyadarsini, R. Karvembu ∗ Department of Chemistry, National Institute of Technology, Tiruchirappalli 620 015, India article info Article history: Received 13 August 2010 Received in revised form 25 October 2010 Accepted 7 November 2010 Available online 13 November 2010 Keywords: Oxidation Alcohols Cu/AlO(OH) Periodic acid Water Room temperature abstract Oxidation of various aliphatic, aromatic, alicyclic, benzylic and allylic alcohols to corresponding carbonyl compounds is studied in water at room temperature over copper on boehmite [Cu/AlO(OH)] catalyst which is prepared from CuCl 2 ·2H 2 O, pluronic P123 and Al(O-sec-Bu) 3 . The prepared catalyst was char- acterized by HR-TEM, SEM-EDX and IR spectroscopy. The reaction conditions for catalytic oxidation of alcohols are optimized with different mole ratio, solvents, and oxidants using 1-phenylethanol system as a model. The scope of the reaction is extended to various types of alcohols. Chemoselectivity, hetero- geneity and reusability tests were performed. The use of water as a solvent at room temperature makes the reaction interesting from both an economic and environmental point of view. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Selective oxidation of alcohols to carbonyl compounds is one of the most pivotal functional group transformations in organic synthesis [1–8], since the products are valuable both as interme- diates as well as being high value components for the perfumery industry [1,9,10]. Aldehydes of low molecular weight are con- densed in an aldol reaction to produce derivatives used in the plasticizer industry. Traditionally, oxidation of alcohols are per- formed with stoichiometric amounts of inorganic oxidants, notably chromium(VI) reagents [11]. These oxidants are not only relatively expensive, but they also generate copious amounts of heavy- metal waste and have toxic issues. Moreover, the reactions are often performed in environmentally undesirable solvents, typi- cally chlorinated hydrocarbons. There are some milder oxidation reactions using Swern and Dess–Martin reagents [12,13]. Swern oxidation releases toxic volatile by-products such as dimethyl sul- fide and carbon monoxide. Dess–Martin periodinane was prepared from 2-iodoxybenzoic acid which usually decomposes explosively. Although individually having some synthetic advantages, most methods suffer from one or more experimental drawbacks such as severe reaction conditions, complicated reaction procedures ∗ Corresponding author. Tel.: +91 431 2503636; fax: +91 431 2500133. E-mail address: kar@nitt.edu (R. Karvembu). and need to use toxic solvents. To overcome this, various cat- alytic methods for the oxidation of alcohols have been developed recently [14]. Hence, the exploration of a mild but efficient oxi- dation method with easy handling and nontoxic green solvent is a challenging area of research in organic synthesis. Many examples of homogeneous systems make use of palladium [15], copper [7] or ruthenium compounds [16], typically in toluene as solvent. The use of an organic solvent, such as toluene, neces- sitates a tedious distillation and cumbersome recovery of the catalyst. Furthermore, the method is not suitable for products that have boiling points close to that of the organic solvent used. Hypervalent iodine reagents have attracted increasing interest as oxidants in organic synthesis due to their mild, selective and environmentally benign oxidizing properties [17]. Periodic acid is used as oxidant in several mild and selective oxidation reac- tions. Chromium trioxide [18], pyridinium chlorochromate [19], fluorochromate [20], bis(trimethylsilyl)chromate [21], chromi- umtris(acetylacetonate) [22], Fe(III)/2-picolinic acid [23] and KBr [24] have been used as catalysts for the oxidation of alcohols with periodic acid. But those reactions are carried out in chlori- nated solvents or other organic solvents and sometimes at elevated temperatures. Hence, we herein report an effective procedure for the selective oxidation of alcohols to the corresponding car- bonyl compounds catalyzed by Cu/AlO(OH) using H 5 IO 6 as oxidant in water at room temperature. Preparation of catalyst is simple 0926-860X/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.apcata.2010.11.012