تهيه و شناسايي نانو كاتاليست اورموسيل اصلاح شده با پورفيرين و كاربرد آن د ر اكسايش اتيل بنزن

چكيده انگليسي :

Synthesis and characterization of modified ormosil nanocatalyst with porphyrin and using it in oxidation of ethylbenzene Fatemeh Mollaee f mollaee@ch iut ac ir 2009 23 02 Department of Chemistry Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiMehran Ghiaci mghiaci@cc iut ac irAbstract Aromatic ketones are important chemical intermediates used in the synthesis of various perfumes drugs andpharmaceuticals The production of these ketones by Friedel Crafts acylation of aromatic compounds alongwith the acyl halide or acid anhydride leads to the formation of a high volume of toxic and corrosive waste Animportant challenge for the green chemistry is to find alternatives to the common oxidation syntheticmethodologies based on stoichiometric oxidants leading to large amounts of non biodegradable by products Nowadays due to economic and ecologic reasons heterogeneous catalysts are of considerable importance Biomimetic catalysts such as metalloporphyrins have been used as cytochrome P 450 models and their potentialfor substrate oxidation has been the subject of several studies The active center of this enzyme is constituted bya heme site that performs a one electron oxidation of substrates in the presence of oxidant as oxygen donor Theuse of metalloporphyrins substituted with electron withdrawing groups and the immobilization on inorganicsupports has resulted in efficient and selective catalysts for the oxidation of hydrocarbon Oxidation ofalkylbenzenes is an important transformation in chemical synthesis generally performed with corrosive toxic orcarcinogenic materials The desired products are usually obtained with low selectivity accompanied byecologically dangerous by products In recent researches the possibility of using of metalloporphyrins as acatalyst in oxidation of such substrates has been proposed by several groups These products strongly dependenton conditions used catalyst co catalyst oxidising agent and solvent The central objective of this research is to carry out oxidation reaction of ethylbenzene and produceacetophenone as the main product using heterogeneous catalyst Thus this projects aims to design aheterogeneous catalyst based on the immobilization of porphyrin on silica gel In order to do this the porphyrincontaining steric functional group entitled 5 10 15 20 tetrakis 4 methoxycarbonyl phenyl porphyrin wassynthesized and immobilized using amidation reaction on modified silica gel containing amino functionalgroup Ultimately immobilized porphyrin was transformed into Mn III complex Different techniques such asUV Vis FT IR CHN TGA and BET were used for the characterization of the catalysts calledSF ATPS Mn III TMCPP Eventually this catalyst was used for oxidation of ethylbenzene The products wereacetophenone benzaldehyde and benzoic acid we were optimized some various reaction conditions such astemperature solvent reaction time oxidant and molar ratio of ethylbenzene in to oxidant to raise theconversion percentage of ethylbenzene and selectivity of acetophenone as the main product The selectivity toacetophenone were increase when the temperature is increased to 150 C The conversion of ethylbenzene andselectivity to acetophenone was maximum under solvent free conditions We have select t butylhydroperoxide 80 TBHP 80 as a best oxidant in the oxidation reaction of ethylbenzene Then we optimized time of thereaction and best results achieved in 6h Ultimately molar ratio of ethylbenzene into TBHP 80 must beinvestigated The conversion of ethylbenzene and selectivity to acetophenone was maximum in 1 3 molar ratioof ethylbenzene TBHP 80 In order to study the catalyst deactivation occurring during the oxidation ofethylbenzene we carried out this reaction several times with modified SF ATPS Mn III TMCPP It is illustratedthat SF ATPS Mn III TMCPP is the active stable and selective catalyst for oxidation of ethylbenzene Key WordsMn III porphyrin ethylbenzene oxidation heterogeneous catalyst

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تهيه و شناسايي نانو كاتاليست اورموسيل اصلاح شده با پورفيرين و كاربرد آن د ر اكسايش اتيل بنزن

منگنز﴿III﴾ , كاتاليست ناهمگن