Reactions of Methyl Iodide and Halopropanes with Na 0 Treated and Untreated NaX and NaY Zeolites
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Reactions of Methyl Iodide and Halopropanes in Na0 Treated and Untreated NaX and NaY Zeolites Charles W. Kanyi, Kaking Yan and Chrispin O. Kowenje. Department of Chemistry, Binghamton University, State University of New York, Binghamton, NY 13902-6000, USA ABSTRACT Products formed from reactions of methyl iodide, 1-chloropropane, 1-iodopropane and 1bromopropane with Na0 treated and untreated NaX and NaY zeolites were studied using solidstate 13C NMR and IR spectroscopy. At room temperature, methyl iodide dissociates to form framework methoxy in untreated NaX zeolite with no reaction observed in untreated NaY. Upon Na0 treatment, both NaX and NaY reacts with methyl iodide to form framework methoxy, methane and ethane. 1-iodopropane undergoes dehalogenation to form framework propoxy while 1-chloropropane and 1-bromopropane undergoes dehalogenation and dehydrohalogenation to form framework propoxy and propene respectively. INTRODUCTION Emission of organo-halogens into the earth’s atmosphere results from naturally occurring, as well as man-made sources. These compounds are usually toxic, particularly through their action on liver functions and may be carcinogenic or mutagenic [1]. Moreover, chlorinated organics are implicated in the destruction of the ozone layer [2] and their release into the environment is being controlled by increasingly stringent regulations [3]. Transformation or decomposition of these organo-halogens to useful products is of economic and environmental interest. Adsorptions on solid surfaces and heterogeneous catalysis have been among the promising methods for removing hazardous and environmentally undesirable chemicals [4]. Although adsorption can occur on a variety of surfaces, only few materials are known to possess adsorptive efficiencies or reactive surfaces sufficiently favorable for adsorbing chlorinated organic compounds. These include activated carbon, zeolites and some metal oxide systems [5-7]. Zeolites are microporous materials that contain three types of nano-sized pores measuring 0.23nm, 0.74 and 1.3 nm in diameter. Owing to their nanostructural size, zeolites contain a high surface area of about 750 m2 per gram. It has been shown that catalytic activity of zeolites can be ascribed to the confinement effect, i.e. interactions between adsorbed molecules and the nanostructured zeolitic pores [8]. Derouane et al. [9] and [10] found that the confinement effects are results of van der Waals interactions which are major factors for determining the strength of interactions between the adsorbed molecule and the zeolite sites. In addition to confinement Faujasite zeolites contains in three major sites. Site I, II and III represent cations in the hexagonal prism, sodalite cage and supercage respectively. NaX contains cations in all the three sites while NaY site III is empty. Methyl iodide undergoes dehalogenation in NaX zeolite at room temperature to form framework methoxy species [11]. The reaction does not take place in NaY at room temperature due to absence of Na+ cations at
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