Thawarkar Sachin R, Thombare Balu, Munde Bhaskar S, Khupse Nageshwar D
Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory Dr. Homi Bhabha Road Pune-411008 India
Department of Physics, Savitribai Phule Pune University Ganeshkhind Pune 411007 India.
RSC Adv. 2018 Nov 14;8(67):38384-38390. doi: 10.1039/c8ra07404f.
We demonstrate the synthesis of gold nanoparticles (AuNP) stabilized by 1-butyl-3-hexadecyl imidazolium bromide (Au@[CCIm]Br) and their use as a catalyst for the reduction of nitrophenol. The AuNPs show excellent stability in presence of [CCIm]Br ionic liquids for the reduction of 4-nitrophenol and 2-nitrophenol using NaBH as a reducing agent. The detailed kinetics for the reduction of 4-nitrophenol and 2-nitrophenol were investigated and the catalytic activity of Au@[CCIm]Br was evaluated. The pseudo first-order rate constant ( ) values for 4-nitrophenol was observed to be greater than that of 2-nitrophenol and explained on the basis of hydrogen bonding present in 2-nitrophenol. Au@[CCIm]Br showed good separability and reusability and hence, it can be used for the complete reduction of nitrophenols in multiple cycles. The Langmuir-Hinshelwood reaction mechanism is elucidated for reduction of 4-nitrophenol by Au@[CCIm]Br nanocatalyst on the basis of the values. The thermodynamic activation parameters such as activation energy, enthalpy of activation and entropy of activation were determined and explained using the temperature dependent kinetics for the reduction of nitrophenol using Au@[CCIm]Br. The above results reveal that the Au@[CCIm]Br nanocatalyst demonstrates excellent catalytic performance for the reduction of nitrophenol by NaBH at room temperature.
我们展示了由1-丁基-3-十六烷基溴化咪唑鎓稳定的金纳米颗粒（AuNP）（Au@[CCIm]Br）的合成及其作为还原硝基苯酚催化剂的用途。在[CCIm]Br离子液体存在下，使用硼氢化钠（NaBH）作为还原剂，AuNP对4-硝基苯酚和2-硝基苯酚的还原表现出优异的稳定性。研究了4-硝基苯酚和2-硝基苯酚还原的详细动力学，并评估了Au@[CCIm]Br的催化活性。观察到4-硝基苯酚的准一级速率常数（ ）值大于2-硝基苯酚的，这是基于2-硝基苯酚中存在的氢键来解释的。Au@[CCIm]Br表现出良好的可分离性和可重复使用性，因此可用于多个循环中硝基苯酚的完全还原。基于 值阐明了Au@[CCIm]Br纳米催化剂还原4-硝基苯酚的Langmuir-Hinshelwood反应机理。使用Au@[CCIm]Br还原硝基苯酚的温度依赖性动力学确定并解释了诸如活化能、活化焓和活化熵等热力学活化参数。上述结果表明，Au@[CCIm]Br纳米催化剂在室温下对NaBH还原硝基苯酚表现出优异的催化性能。
