Publications by authors named "Thiyagarajan Subramanian"

The coupling of mononitriles into dinitriles is a desirable strategy, given the prevalence of nitrile compounds and the synthetic and industrial utility of dinitriles. Herein, we present an atom-economical approach for the heteroaddition of saturated nitriles to α,β- and β,γ-unsaturated mononitriles to generate glutaronitrile derivatives using a catalyst based on earth-abundant manganese. A broad range of such saturated and unsaturated nitriles were found to undergo facile heteroaddition with excellent functional group tolerance, in a reaction that proceeds under mild and base-free conditions using low catalyst loading.

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Atom-economical catalytic reactions are a highly enticing strategy because all atoms of the starting materials are incorporated into the products. Catalytic hydrogenation of epoxides to alcohols is an attractive and alternative protocol to other synthetic methodologies for the synthesis of alcohols from alkenes. In the last two decades, catalytic hydrogenation of epoxides to alcohols has made remarkable progress in chemical synthesis.

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Herein, an efficient and simple catalytic method for the selective and partial reduction of aldazines using ruthenium catalyst [Ru(p-cymene)Cl] (1) has been accomplished. Under mild conditions, aldazines undergo the addition of pinacolborane in the presence of a ruthenium catalyst, which delivered N-boryl-N-benzyl hydrazone products. Notably, the reaction is highly selective, and results in exclusive mono-hydroboration and desymmetrization of symmetrical aldazines.

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Article Synopsis
  • An assortment of aromatic ketones was effectively functionalized using unactivated secondary alcohols as alkylating agents, resulting in β-disubstituted ketones with good to excellent yields.
  • Remarkably, even challenging substrates like acetophenone derivatives were successfully alkylated through ruthenium catalysis, showcasing the method's versatility.
  • The process involves a hydrogen-borrowing mechanism, requires minimal catalyst and base, and generates only water as a byproduct, making it an environmentally friendly option for C-C bond formation.
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Herein, direct N,N-dialkylation of acylhydrazides using alcohols is reported. This catalytic protocol provides one-pot synthesis of both symmetrical and unsymmetrical N,N-disubstituted acylhydrazides using an assortment of primary and secondary alcohols with remarkable selectivity and excellent yields. Interestingly, the use of diols resulted in intermolecular cyclization of acylhydrazides, and such products are privileged structures in biologically active compounds.

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Designed transition metal complexes predominantly catalyze Michael addition reactions. Inorganic and organic base-catalyzed Michael addition reactions have been reported. However, known base-catalyzed reactions suffer from the requirement of solvents, additives, high pressure and also side-reactions.

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The exhaust emissions from the compression ignition engines are harmful to both human beings and the environment. After-treatment devices placed in the exhaust are designed to reduce these emissions. These devices have significant conversion efficiency but have various drawbacks such as the cost and availability of the precious catalyst for catalytic converters.

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A ruthenium(II)-catalyzed highly selective Markovnikov hydrogenation of terminal epoxides to secondary alcohols is reported. Diverse substitutions on the aryl ring of styrene oxides are tolerated. Benzylic, glycidyl, and aliphatic epoxides as well as diepoxides also underwent facile hydrogenation to provide secondary alcohols with exclusive selectivity.

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This study is focused on artificial neural network (ANN) modelling of non-modified diesel engine keyed up by the combination of two low viscous biofuels to forecast the parameters of emission and performance. The diesel engine is energised with five different test fuels of the combination of citronella and Cymbopogon flexuous biofuel (C50CF50) with diesel at precise blends of B20, B30, B40, B50 and B100 in which these numbers represent the contents of combination of biofuel and the investigation is carried out from zero to full load condition. The experimental result was found that the B20 blend had improved BTE at all load states compared with the remaining biofuel blends.

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Stringent emission norms impose challenges to original equipment manufacturer (OEM) in reducing diesel engine emissions. Implementing renewable fuels as alternative energy sources in diesel engines leads to increased emission levels particularly NO. In this work, performance, combustion, and emission parameters from a diesel engine powered with grapeseed oil biodiesel (GSBD) was investigated.

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The present work details the effects of injection of higher order alcohols, namely hexanol (Hex) and octanol (Oct) as secondary fuels in a CI engine. The last decade has seen an exponential increase in the carbon emission chief of which have been contributed by fossil fuels. Vegetable oils provide a viable alternative to the current scenario as they can be synthesized easily from nature and can be readily adapted for use in CI engines.

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The present study presented an inclusive analysis of engine exhaust emission characteristics of direct injection diesel engine fuelled with diesel and biofuel. Biofuel used in this investigation was obtained by steam distillation from pine oil. A single-cylinder, four-stroke diesel engine was used for this purpose.

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Direct one-pot synthesis of ketazines from secondary alcohols and hydrazine hydrate catalyzed by a ruthenium pincer complex is reported, which proceeds through O-H bond activation of secondary alcohols via amine-amide metal-ligand cooperation in the catalyst. Remarkably, liberated molecular hydrogen and water are the only byproducts.

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Herein, an unprecedented ruthenium(II) catalyzed direct cross-coupling of two different secondary alcohols to β-disubstituted ketones is reported. Cyclic, acylic, symmetrical, and unsymmetrical secondary alcohols are selectively coupled with aromatic benzylic secondary alcohols to provide ketone products. A single catalyst oxidizes both secondary alcohols to provide selectively β-disubstituted ketones to broaden the scope of this catalytic protocol.

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The present study investigates the effect of blending oxygenate namely diethylene glycol dimethyl ether (diglyme) with minor vegetable oil namely rubber seed oil (RSO), babassu oil (BSO), and their blends in various proportions (R75B25, R50B50, and R25B75) on NOx-smoke trade-off and other engine characteristics. The tests were conducted on a commercial twin cylinder compression-ignition (CI) engine commonly used in tractors. The potential of the blends with diglyme is assessed based on performance, emission, and combustion characteristics of the engine at different load conditions.

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The present study intends to explore the effect of the addition of fuel additives with camphor oil (CMO) on the characteristics of a twin-cylinder compression ignition (CI) engine. The lower viscosity and boiling point of CMO when compared to diesel could improve the fuel atomization, evaporation, and air/fuel mixing process. However, the lower cetane index of CMO limits its use as a drop in fuel for diesel in CI engine.

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The present study deals with performance, emission and combustion studies in a single cylinder CI engine with lower and higher alcohol fuel synergies with biofuel blends and exhaust treatment system. Karanja oil methyl ester (KOME), widely available biofuel in India, and orange oil (ORG), a low carbon biofuel, were taken for this study, and equal volume blend was prepared for testing. Methanol (M) and n-pentanol (P) was taken as lower and higher alcohol and blended 20% by volume with KOME-ORG blend.

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