دانلود رایگان مقاله لاتین اکسیداسیون آلیلیک کاتالیز سیکلوهگزین از سایت الزویر
عنوان فارسی مقاله:
اثر حلال بر اکسیداسیون آلیلیک کاتالیز سیکلوهگزین با نانولوله های کربنی آلاییده شده نیتروژن
عنوان انگلیسی مقاله:
Solvent effect on the allylic oxidation of cyclohexene catalyzed by nitrogen doped carbon nanotubes
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
The selective oxidation of hydrocarbons towards oxygenated derivatives is a significant chemical value-chain, through which the relatively cheap molecules can be converted into value-added products [1–3]. Numerous studies have demonstrated that solvents display a dramatic influence on the catalytic activity and products distributions, especially for the oxidation of alkenes [2,4–7]. The solvent properties, such as polarity, dielectric constant and basicity, influenced the activity of the epoxidation of styrene, 1-hexene and cyclohexene over titanosilicate catalysts [6,8]. In addition, a synergistic effect between the solvent property and the hydrophilicity–hydrophobicity of the zeolite also affected the catalytic activity, as observed in the case of 1-hexene oxidation towards the production of alcohol and 2-cyclohexen-1-one [9]. Fan et al. investigated the solvent effects on the activity, epoxide selectivity, and H2O2 efficiency in the liquid-phase epoxidation of 1-hexene and cyclohexene over three types of zeolites (TS-1, Ti-Beta, and TiMWW) [6]. The literature results indicate that solvents may interplay with the active sites on catalyst surfaces, thereby modify the reaction pathway and the distribution of products in the alkene oxidation reactions [6,10]. However, the manner of solvent affecting the reaction might be changed as the catalyst is upgraded. Nanocarbons have attracted great attentions from the research and industrial communities in the past two decades as metal-free catalysts, due to their unique chemical and physical properties [11–13]. Recently, nanocarbons, especially nitrogen doped carbon nanotubes (NCNTs), displayed excellent performance in the allylic oxidation of cyclohexene, affording a high selectivity of 2-cyclohexene-1- none [14]. The remarkable activity can be explained by the stabilization of peroxyl and cycloxyl radicals and the charge transfer between NCNTs and radicals, which is facilitated by delocalized electrons in graphene layers [14–16]. The significant solvent effect in the selective oxidation of hydrocarbons catalyzed by carbons has been observed. For instance, Yang et al. found that the unique catalytic efficiency of the hydroxylation of benzene catalyzed by graphene in immiscible water as solvent, because the products can be rapidly transferred to solvent to avoid the over-oxidation [5]. Our very recently work also revealed that solvents could greatly influence the activity of α-pinene oxidation over CNTs [17]. Despite these achievements, a comprehensive understanding to the solvent effect on the alkene oxidation is so far unavailable, because the library of solvents was usually too small to uncover the general tendency of solvent effect. Moreover, the synergy between solvents and carbon catalysts has not been revealed. In this work, we have studied the effect of solvents on the allylic oxidation of cyclohexene catalyzed by NCNTs. To achieve an in-depth understanding, 22 organic solvents were investigated, which are categorized into four types, namely protic/aprotic aliphatics/aromatics,according to their properties and structures. By correlating the catalytic performance with the solvent properties, i.e. viscosity, polarity and scale of basicity, the solvent effect could be rationalized.
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کلمات کلیدی:
Highly selective oxidation of cyclohexene to 2 ... - RSC Publishing pubs.rsc.org/-/content/articlehtml/2016/cy/c5cy01177a by D Yang - 2016 - Cited by 11 - Related articles Sep 11, 2015 - The influence of supports, solvents, Fe/Co molar ratio in the catalysts, ... For example, the allylic oxidation of cyclohexene over cobalt resinate ... catalytic performance and expanded the applications of g-C3N4 in catalysis. ..... The effect of reaction temperature on the oxidation of cyclohexene is shown in Fig. Recent Advances in Basic and Applied Aspects of Industrial Catalysis https://books.google.com/books?isbn=0080540384 T.S.R. Prasada Rao, G. Murali Dhar - 1998 - Technology & Engineering These complexes were used for the catalytic oxidation of cyclohexene and styrene with ... The effect of various solvents on the oxidation reactions was studied. ... In this complex the selectivity for the formation of the allylic oxidation products ... Iron Catalysis in Organic Chemistry: Reactions and Applications https://books.google.com/books?isbn=3527623280 Bernd Plietker - 2008 - Science However, virtually no trace of allylic oxidation was found for cycloheptene 1e and cyclooctene 1f. ... For example, the catalytic oxidation of cyclohexene 1a with molecular ... A remarkable solvent effect on the chemoselectivity was discovered by ... Oxidation mechanism of molecular oxygen over cyclohexene ... pubs.rsc.org/-/content/articlepdf/2016/ra/c6ra23598k by YN Wei - 2016 - Related articles Oct 18, 2016 - allylic oxidation of cyclohexene is catalyzed by homogenous and .... The effect of four reaction parameters namely solvent selection, reaction ... Modern Heterogeneous Oxidation Catalysis: Design, Reactions and ... https://books.google.com/books?isbn=3527627553 Noritaka Mizuno - 2009 - Science Cyclohexene oxidation with H2O2 results in allylic oxidation and epoxidation ... 4.2.5 Solvent Effects and Reaction Intermediate The role of the solvent is ...
