%0 Journal Article
%T Studies on the Iron Nanoparticles Catalyzed Reduction of Substituted Aromatic Ketones to Alcohols
%A L. Parimala
%A J. Santhanalakshmi
%J Journal of Nanoparticles
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/156868
%X Iron nanoparticles are synthesized and size characterized using HRTEM, FESEM, and XRD. Polyethylene glycol(PEG), carboxymethyl cellulose (CMC), and poly N-vinyl pyrrolidone (PVP) are used as nanoparticle stabilizers. The sizes of Fe nps are found to be 9£¿nm, 14£¿nm, and 17£¿nm£¿¡À£¿1£¿nm corresponding to PEG, CMC, and PVP stabilizers, respectively. The three different iron nanoparticles (Fe nps) prepared are used as catalysts in the hydrogenation reaction of various substituted aromatic ketones to alcohols with NaBH4. The progress of the reaction was monitored using time variance UV spectra. Kinetic plots are made from the absorbance values and the pseudo first order rate coefficient values are determined. Catalytic efficiency of the Fe nps is obtained by comparing the pseudo first order rate coefficient values, times of reaction, and % yield. Fe-PEG nps was found to act as better catalyst than Fe-CMC nps and Fe-PVP nps. Also, effects of substituents in the aromatic ring of ketones reveal that +I substituents are better catalysed than ¨CI substituents. 1. Introduction Reduction reactions of carbonyl compounds to primary and secondary alcohols possess one of the important classes of organic reactions that are well used in synthetic chemistry [1¨C5]. Such reactions find immense applications in chemical industries related to fine chemicals, pharmaceuticals, perfumes, and agrochemicals. Transition metal catalyzed reduction reactions are considered as popular substitutes of platinum metal based catalysts. Cost effectiveness, abundance, stability, recyclability, environmentally benign, and relatively nontoxic are some of the reasons for the important role of tranisition metals in catalysis. Decades of research involve traditional catalysts for ketone hydrogenation reactions involving precious metals and their coordination complexes [6¨C12]. Rhodium and ruthenium complexes using chiral phosphines and amines as ligands show excellent catalytic activity towards asymmetric hydrogenation of prochiral ketones and other carbonyl compounds. However, these catalysts have limited applications because of their high cost and difficulty in the separation of products from chiral catalyst. There have been several attempts to develop iron catalysts for these kinds of reactions, because these would be cheaper and nontoxic [13, 14]. In this regard, Chirik¡¯s, Beller¡¯s, and Nishiyama¡¯s groups have recently reported useful iron catalysts for the hydrosilation of aldehydes and ketones [7, 15] and their transfer hydrogenation. Efforts to find catalysts that do not require noble metals are
%U http://www.hindawi.com/journals/jnp/2014/156868/