02417nas a2200241   4500008004100000022001400041245013200055210006900187260000800256300001200264490000700276520156800283653002301851653002801874653002001902653001601922653002201938653002201960100002601982700002002008700002302028856012402051       2021                        eng d  a0538-806600aEstimation of reaction kinetics for aromatic and heterocycles nitration in mixed acids through computational chemistry approach0 aEstimation of reaction kinetics for aromatic and heterocycles ni  cMAR  a319-3320 v533 a<p>Nitration of aromatic compounds and heterocycles in mixed acid environment is one of the regularly performed large-scale reactions in the chemical industry. Although the reaction mechanism of nitration of aromatics in mixed acid is well established, the development of a methodology for the evaluation of kinetics of exothermic aromatic nitrations in a simplified and accurate way is necessary. Here we evaluate the applicability of a kinetic evaluation methodology based on Hammett's acidity function, acidity function, and empirical activity coefficient for the nitration reaction. The contributions from the functional groups on the aromatic ring and quantitative structure-activity relationships technique are considered for these evaluations. Natural bond orbital and magnetic index nucleus independent chemical shift analyses were carried out to obtain the substitution constants. The rate constant and activation energy values were evaluated at various temperatures and sulfuric acid strengths. The results were validated by comparing with the experimental data from the literature for several molecules. The effect of various functional groups (viz carbonyl, carboxyl, methyl, and amine) substituted on the benzene ring was also evaluated. For a few identified substrates, the data were used for estimation of residence time needed for complete conversion in continuous stirred tank reactor and in a plug flow reactor to quantify the effect of substitution constant and strength of sulfuric acid. The approach will help select a suitable reactor.</p>
10aAromatic nitration10acomputational chemistry10aHammett analogy10amixed acids10aReaction kinetics10areactor selection1 aJadhav, Pandurang, M.1 aPandey, Raj, K.1 aKulkarni, Amol, A.  uhttps://library.ncl.res.in/content/estimation-reaction-kinetics-aromatic-and-heterocycles-nitration-mixed-acids-through02210nas a2200253   4500008004100000022001400041245008500055210006900140260000800209300001100217490000800228520140200236653002001638653001101658653001501669653002201684653002601706653002101732100001801753700002101771700002701792700002301819856011401842       2021                        eng d  a1385-894700aQuantitative understanding of nucleation and growth kinetics of silver nanowires0 aQuantitative understanding of nucleation and growth kinetics of   cJUN  a1287110 v4143 a<p>We have demonstrated that using polyol synthesis, it is possible to prepare high aspect ratio silver nanowires by controlling the experiments for process related issues which are usually ignored, viz. the overhead space in the batch reactor. It is found that by controlling the presence/absence of NOx gases with refluxing of nitric acid in the batch reactor with an overhead space of 80% volume, near complete conversion (-99%) of high aspect ratio NWs (-1000) can be attained. We provide a detailed understanding of other factors assisting in rapid polyol synthesis like temperature, stirring rate, Chloride ion concentration, optimal PVP weight ratios and PVP/AgNO3 ratio that can lead to high aspect ratio NWs. Besides the process parameters and reagent concentration effects, kinetic studies based on our nucleation and R-C Model evaluate the overall reaction rate constants for silver nanowires and the JMAK approach is used to theoretically validate our experimental results of the reactor headspace having strongest effect on the aspect ratios. Our study highlights the importance of various complications in the polyol synthesis, through detailed kinetic modelling and affixes values of temperature, reactor headspace, stirring rate and residence time in order to achieve reproducible synthesis of nanowires with complete conversion along with a method to separate these nanowires.</p>10aConducting inks10agrowth10aNucleation10aReaction kinetics10aRedox-crystallization10aSilver Nanowires1 aPatil, Suneha1 aKate, Prachi, R.1 aDeshpande, Jaydeep, B.1 aKulkarni, Amol, A.  uhttps://library.ncl.res.in/content/quantitative-understanding-nucleation-and-growth-kinetics-silver-nanowires