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Heterogeneous polymer supported and soluble tantalum metal complex catalysts for acylation reaction: A kinetic study
Indian Journal of Chemical Technology ( IF 0.5 ) Pub Date : 2021-12-24
E Murugan, P Arunachalam, J Nimita Jebaranjitham, S Santhoshkumar, A Saravanakumar

New soluble and insoluble Tantalum pentachloride complex catalysts are prepared by simple procedures using pyridine and polymer-supported cross-linked (poly-4-vinyl pyridine) beads (PSCPVP) respectively as supports and Tantalum pentachloride as a catalytic moiety (TaCl5). The prepared soluble Py-TaCl5 and insoluble bead-shaped PSCPVP-TaCl5 catalysts have been characterized with FT-IR, UV-Vis, SEM, TGA and elemental analysis techniques. The catalytic efficiency of these catalysts has been examined through acylation of ethanol as a model reaction under identical pseudo first order reaction condition. From the calculated kobs values, it has been noticed that both the catalysts are active and however, Py-TaCl5shown 1.65 fold has increased activity (kobs =11.42x103 min-1) than insoluble PSCPVP-TaCl5 catalyst (kobs= 6.98x103, min-1). Although, PSCPVP-TaCl5 has shown lesser activity than soluble due to its lower cost, recyclability and reusable nature up to third cycle, it has received greater recognition. Hence, in order to utilize this insoluble bead-shaped PSCPVP-TaCl5 catalyst to pack in column reactor and to carry out the same reaction for continuous mode operation at industrial level, detailed kinetics study for acylation of ethanol has been conducted under pseudo first order condition by varying the different experimental parameters and has observed that each parameter has influenced the reaction. The obtained kobs value reveals that reaction rates increase with the increase in the stirring speed, [substrate], [catalyst] and temperature. The thermodynamic parameters viz., activation energy (Ea), entropy (∆S), enthalpy (∆H) and free energy (∆G#) for the reaction are also calculated for the first time and their observed values are 35.2 kJmol-1, -64.6 kJ-1mol-1, 37.7 kJmol-1and 57.3 kJmol-1 respectively. The prepared insoluble catalyst is stable even after its use for three times in acylation without losing its efficiency, thus it is better suited for industrial applications.

中文翻译:

用于酰化反应的多相聚合物负载的可溶性钽金属络合物催化剂:动力学研究

新的可溶性和不溶性五氯化钽络合物催化剂是通过简单的程序制备的,分别使用吡啶和聚合物负载的交联(聚 4-乙烯基吡啶)珠(PSCPVP)作为载体,使用五氯化钽作为催化部分(TaCl5)。用FT-IR、UV-Vis、SEM、TGA和元素分析技术对制备的可溶性Py-TaCl5和不溶性珠状PSCPVP-TaCl5催化剂进行了表征。在相同的准一级反应条件下,通过乙醇酰化作为模型反应来检验这些催化剂的催化效率。从计算的 kobs 值可以看出,这两种催化剂都具有活性,但是,与不溶性 PSCPVP-TaCl5 催化剂(kobs= 6.98x103, min- 1)。虽然,PSCPVP-TaCl5由于其成本较低、可回收和可重复使用至第三次循环而表现出低于可溶性的活性,它得到了更多的认可。因此,为了利用这种不溶性珠状 PSCPVP-TaCl5 催化剂填充柱式反应器并在工业水平上进行连续模式操作的相同反应,在伪一级条件下进行了乙醇酰化的详细动力学研究通过改变不同的实验参数并观察到每个参数都影响了反应。得到的 kobs 值表明反应速率随着搅拌速度、[底物]、[催化剂]和温度的增加而增加。热力学参数,即活化能 (Ea)、熵 (∆S)、还首次计算了反应的焓(ΔH)和自由能(ΔG#),观测值分别为35.2 kJmol-1、-64.6 kJ-1mol-1、37.7 kJmol-1和57.3 kJmol-1 . 所制备的不溶性催化剂在酰化反应中使用3次后仍能保持稳定而不失效率,因此更适合工业应用。
更新日期:2021-12-24
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