Applied Catalysis A: General 505 (2015) 213–216 Contents lists available at ScienceDirect Applied Catalysis A: General jou rn al hom ep age: www.elsevier.com/locate/apcata Solvent-free hydration of alkynes over H zeolite Naresh Mameda a,b , Swamy Peraka a,b , Mahender Reddy Marri b , Srujana Kodumuri b , Durgaiah Chevella b , Naresh Gutta b , Narender Nama a,b,∗ a Academy of Scientific and Innovative Research, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India b Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India a r t i c l e i n f o Article history: Received 28 May 2015 Received in revised form 23 July 2015 Accepted 27 July 2015 Available online 30 July 2015 Keywords: Alkynes Heterogeneous catalyst Hydration Solvent-free reactions Zeolites a b s t r a c t An efficient and environmentally benign catalytic system has been successfully developed for highly Markovnikov selective hydration of various alkynes over heterogeneous catalyst (H zeolite) in solvent- free conditions. The catalyst (H zeolite) is commercial available, recyclable and exhibits excellent catalytic activity towards the hydration of alkynes to ketones. Moreover, the propargylic aryl carbinols undergo Meyer–Schuster rearrangement to give ,-unsaturated carbonyl compounds in excellent yields. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Catalytic hydration of CC triple bond is one of the most straight- forward and environmentally benign method to form C O bond. In this respect, Markovnikov hydration of alkynes is a convenient and efficient method for the production of ketones and the reaction involves the simple addition of a water molecule to the alkyne with 100% atom efficiency [1,2]. Ketones are unambiguously important motifs in modern organic synthesis. Mercury (II) salts combined with acids, such as HgO/H 2 SO 4 and HgO/BF 3 , are reliable catalysts for the hydration of alkynes and these catalysts were extensively used in high-scale industrial processes until the discovery of the toxicity of mercury salts [3,4]. Alternative metallic catalysts have been searched over the years, mainly transition metal based cata- lysts, such as Pt [5,6], Fe [7,8], Pd [9], Ir [10], Ag [11,12], Os [13] and Au [14,15]. Whereas, most of these metal catalysts have shortcom- ings, such as lower reactivity, recovery and reuse of (expensive) catalysts and prohibit their frequent use for laboratory as well as industrial purpose. In addition, use of concentrated solution of strong acids (H 2 SO 4 [16], CF 3 SO 3 H [17] and PTSA [18]) is known to ∗ Corresponding author at: Academy of Scientific and Innovative Research, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India. Fax: +91 40 27160387/757. E-mail addresses: narendern33@yahoo.co.in, nama@iict.res.in (N. Nama). promote the alkyne hydration process. Nevertheless, it not always fruitful for large scale preparations. In recent years, green and economical considerations have raised strong attention to redesign commercially important pro- cesses to avoid the use of harmful reagents and the generation of toxic waste. In this respect, the development of easily recyclable and recoverable heterogeneous catalysts can solve the problems of the homogeneous systems and has received particular research interest by synthetic organic chemists [19]. In view of this, the hydration of 4-ethynyltoluene over heterogeneous polystyrene supported sulfonic acid using a catalytic amount of triflic acid was reported by Kobayashi et al. [20]. But applicability of this method is limited to only 4-ethynyltoluene. Hexing Li and coworkers reported the Au I -modified mesoporous silica for the hydration of alkynes [21]. Although, this catalyst showed high efficiency, mineral acid (H 2 SO 4 ) is required as a co-catalyst (10 mol%). Later Mizuno and coworkers [22] reported an efficient hydration of various alkynes using heterogeneous Sn–W mixed oxide catalyst. However, main drawback associated with this method is the need of organic sol- vent as reaction medium. For reasons of economy and pollution prevention, solvent-free methods [23,24] are used to revise classical procedures by mak- ing them cleaner, safer and easier to perform. To the best of our knowledge, there are only two reports on the solvent-free hydra- tion of alkynes using heterogeneous catalysts, for example, Au nanoparticle-acid catalyst (Au–HS/SO 3 H-PMO(Et) [25] and silver http://dx.doi.org/10.1016/j.apcata.2015.07.038 0926-860X/© 2015 Elsevier B.V. All rights reserved.