@article { ISI:000230297800031, title = {Catalyzing Henry reactions in chloroaluminate ionic liquids}, journal = {Journal of Molecular Catalysis A - Chemical}, volume = {235}, number = {1-2}, year = {2005}, month = {JUL}, pages = {244-248}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Henry reactions can be accelerated in chloroaluminate room temperature ionic liquids. The choloroaluminates with higher compositions of organic species of the chloroaluminates prove to be more efficient rate promoters than the ones with lower organic species in catalyzing Henry reactions. involving both aliphatic and aromatic carbonyl compounds. The ionic liquids can be recycled five times to offer good yields. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {chloroaluminates, Henry reactions, ionic liquids, Recycling}, issn = {1381-1169}, doi = {10.1016/j.molcata.2005.04.010}, author = {Kumar, Anil and Pawar, Sanjay S.} } @article { ISI:000227293600028, title = {Comment on {\textquoteleft}{\textquoteleft}Prediction of viscosity of mixed electrolyte solutions based on the Eyring{\textquoteright}s absolute rate theory and the equations of Patwardhan and Kumar by Y.-F. Hu{\textquoteright}{\textquoteright} (Chemical Engineering Science 2003,59,2457-2464)}, journal = {Chemical Engineering Science}, volume = {60}, number = {6}, year = {2005}, month = {MAR}, pages = {1793-1795}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, issn = {0009-2509}, doi = {10.1016/j.ces.2004.11.008}, author = {Kumar, Anil} } @article { ISI:000237716500031, title = {Comparison of flow structures in spacer-filled flat and annular channels}, journal = {Desalination}, volume = {191}, number = {1-3}, year = {2006}, note = {International Congress on Membranes and Membrane Processes, Seoul, SOUTH KOREA, AUG 21-26, 2005}, month = {MAY}, pages = {236-244}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Spacers are designed to create directional changes in the flow through membrane modules. Such secondary flow structures reduce concentration polarization and membrane fouling. Obviously, type of the spacer used in membrane modules strongly influences the resulting flow and therefore performance of the module. In this work, we have modeled detailed fluid dynamics of spacer filled channels by using the {\textquoteleft}unit cell{\textquoteright} approach. The validated computational fluid dynamics (CFD) model was used to evaluate performance of certain spacer shapes and compare the resulting fluid dynamics in flat and curved channels. The simulations show that fluid flow behavior in a spacer-filled flat and a spiral channel was not significantly different. This means that pressure drops and mass transfer coefficients measured in flat channels may provide adequate guidelines, which would also be valid for spiral-wound modules. The results presented in this work will have significant implications for identifying improved spacers with higher propensities to reduce fouling in membrane modules.

}, keywords = {annular channel, CFD, flat channel, membrane spacers}, issn = {0011-9164}, doi = {10.1016/j.desal.2006.03.003}, author = {Ranade, Vivek V. and Kumar, Anil} } @article { ISI:000261342600009, title = {Correlations of thermodynamic properties of aqueous amino acid-electrolyte mixtures}, journal = {Journal of Solution Chemistry}, volume = {38}, number = {1}, year = {2009}, month = {JAN}, pages = {95-114}, publisher = {SPRINGER/PLENUM PUBLISHERS}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Suitable equations have been proposed to correlate thermodynamic properties, like mean ion activity coefficients, volumes and compressibilities, of amino acids in electrolyte solutions. An amino acid-electrolyte-water interaction parameter is extracted from the regression of the amino acid property values in aqueous electrolyte solution that is then transferred to an expression to correlate the properties of the electrolyte in mixtures. The single interaction parameter can successfully correlate the published data on mean ion activity coefficients, apparent molar volumes and compressibilities of amino acids as well as of electrolytes in their aqueous mixtures. The equations are tested against the large number of experimental data sets available in the literature.

}, keywords = {Amino acids, Electrolytes, Pitzer equation, Thermodynamic properties}, issn = {0095-9782}, doi = {10.1007/s10953-008-9355-2}, author = {Saritha, C. and Satpute, Dilip B. and Badarayani, Rohini and Kumar, Anil} } @article { ISI:000273404500044, title = {Contrasting thermosolvatochromic trends in pyridinium-, pyrrolidinium-, and phosphonium-based ionic liquids}, journal = {Journal of Physical Chemistry B}, volume = {114}, number = {1}, year = {2010}, month = {JAN}, pages = {376-381}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Thermosolvatochromism has been studied in three series of ionic liquids, pyridinium-based 1-butylpyridinium, 1-hexylpyridinium, and 1-octylpyridinium with bis(trifluoromethylsulfonyl)imide [NTf2] and tetrafluoroborate [BF4] anions, pyrrolidinium-based ionic liquids 1-methyl-1-butylpyrrolidium, 1-methyl-1-hexylpyrrolidium, 1-methyl-1-octylpyrrolidium with bis(trifluoromethylsulfonyl) imide anion and phosphonium-based ionic liquids tetrabutylphosphonium with alanate and valinate anions. The effect of increase in alkyl chain length and temperature on normalized polarity E-T(N), Kanilet-Taft parameters, hydrogen bond donor ability (alpha), hydrogen bond acceptor ability (beta), and polarizability (pi*) was investigated in the temperature range of 298-353 K. Interestingly, the polarity decreases with temperature in the case of pyridinium- and pyrrolidinium-based ionic liquids, and it increases with temperature in the case of phosphonium-based ionic liquids.

}, issn = {1520-6106}, doi = {10.1021/jp908498p}, author = {Khupse, Nageshwar D. and Kumar, Anil} } @article { ISI:000294701300010, title = {Cosolvent-directed diels-alder reaction in ionic liquids}, journal = {Journal of Physical Chemistry A}, volume = {115}, number = {36}, year = {2011}, month = {SEP}, pages = {10211-10217}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The rate constants of a bimolecular Diels-Alder reaction in binary mixtures of ionic liquids prepared in molecular solvents were analyzed to investigate the effect of viscosity of the medium and solvent effect. In this connection, we have carried out the Diels-Alder reaction of anthracene 9-carbinol with N-ethyl maleimide in binary mixtures of pyridinium-based ionic liquids, 1-butyl-pyridinium tetrafluoroborate, 1-buty1-3-pyridinium tetrafluoroborate, and 1-butyl-4-methyl pyridinium tetrafluoroborate in water, methanol, and chloroform at 298.15 K. The rates of reaction decreased, caused by gradually increasing the volume fraction of ionic liquids in solvents for all three ionic liquids. The kinetic results demonstrate a successful application of the pairwise interaction model built upon the concept of enforced hydrophobic hydration. A temperature-dependent study of kinetics of the Diels-Alder reaction was carried out in the binary mixtures of ionic liquids in water and was explained by the entropy-enthalpy compensation effect based upon activation parameters. Kinetics of the Diels-Alder reaction in highly aqueous medium was noted to be entropically driven.

}, issn = {1089-5639}, doi = {10.1021/jp205181e}, author = {Khupse, Nageshwar D. and Kumar, Anil} } @article { ISI:000345075400006, title = {Calorimetric elucidation of ionic interactions in room temperature ionic liquid solutions}, journal = {Clean Technologies and Environmental Policy }, volume = {16}, number = {8, SI}, year = {2014}, month = {DEC}, pages = {1529-1536}, publisher = {SPRINGER}, type = {Review}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Knowledge of thermal properties of room temperature ionic liquid (RTIL) solutions is essential in chemical process designing in addition to their application in understanding ionic interactions at molecular level. RTILs are considered to be substitutes for volatile organic compounds. While some experimental thermal data on these systems are available in a random manner, the modeling efforts to correlate enthalpy-concentration profiles of RTIL solutions are very scanty. In this review, an effort has been made to compare and discuss the experimental data of these RTIL solutions available in the literature. The readers are also made aware of the disappointing situation regarding the availability of any type of correlative models for the enthalpy-concentration data of the RTIL systems. An accurate knowledge of activity coefficients at infinite dilutions, Iyen (i) (a) acquired from thermal data will serve as inputs for the newer less polluting process designing and thus open opportunity for a cleaner environment.

}, keywords = {Calorimeters, Correlative models, Excess partial molar enthalpy, Room temperature ionic liquids}, issn = {1618-954X}, doi = {10.1007/s10098-013-0644-0}, author = {Rai, Gitanjali and Kumar, Anil} } @article {42556, title = {Can a diels-alder reaction accelerate in a supersaturated solvent at room temperature?}, journal = {New Journal of Chemistry}, volume = {40}, year = {2016}, month = {AUG}, pages = {8355-8363}, abstract = {

A new supersaturated solvent is proposed to accelerate the Diels{\textendash}Alder reaction between cyclopentadiene and methyl acrylate by several times. The proposed supersaturated solvent consists of various carbohydrates, organic acid and organic ketone in water, beyond their solubility limits in water, at room temperature. The results demonstrate that the presence of excess {\textendash}OH groups from the carbohydrates plays a pivotal role leading to the increased reactivity and selectivity of the Diels{\textendash}Alder reaction. The role of hydrogen bond accelerators and polarity of the solvent have been analyzed through a comparative study of the same reaction in similar green solvents. Collision-controlled reaction theory has been invoked to understand the role of encounter complexes to accelerate such a reaction at the molecular level in such highly viscous supersaturated solvent. No detrimental effects from the high viscosity of the new solvent medium on the reaction kinetics was been noted.

}, doi = {10.1039/C6NJ01912A}, author = {Nagare, Amit S. and Manna, Arpan and Kumar, Anil} } @article { ISI:000373738200010, title = {Comparative investigation of the ionicity of aprotic and protic ionic liquids in molecular solvents by using conductometry and NMR spectroscopy}, journal = {Chemphyschem}, volume = {17}, number = {7}, year = {2016}, month = {APR}, pages = {1006-1017}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

Electrical conductivity (sigma), viscosity (), and self-diffusion coefficient (D) measurements of binary mixtures of aprotic and protic imidazolium-based ionic liquids with water, dimethyl sulfoxide, and ethylene glycol were measured from 293.15 to 323.15K. The temperature dependence study reveals typical Arrhenius behavior. The ionicities of aprotic ionic liquids were observed to be higher than those of protic ionic liquids in these solvents. The aprotic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, [bmIm][BF4], displays 100\% ionicity in both water and ethylene glycol. The protic ionic liquids in both water and ethylene glycol are classed as good ionic candidates, whereas in DMSO they are classed as having a poor ionic nature. The solvation dynamics of the ionic species of the ionic liquids are illustrated on the basis of the (HNMR)-H-1 chemical shifts of the ionic liquids. The self-diffusion coefficients D of the cation and anion of [HmIm][CH3COO] in D2O and in [D-6]DMSO are determined by using H-1 nuclei with pulsed field gradient spin-echo NMR spectroscopy.

}, keywords = {conducting materials, Electrochemistry, electrostatic interactions, Ion pairs, ionic liquids}, issn = {1439-4235}, doi = {10.1002/cphc.201501156}, author = {Thawarkar, Sachin and Khupse, Nageshwar D. and Kumar, Anil} } @article { ISI:000369480600051, title = {Concentration-dependent apparent partition coefficients of ionic liquids possessing ethyl-and bi-sulphate anions}, journal = {Physical Chemistry Chemical Physics}, volume = {18}, number = {2}, year = {2016}, month = {JAN}, pages = {1105-1113}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

This study deals with the concentration dependent apparent partition coefficients log P of the ethyl and bisulfate-based ionic liquids. It is observed that the bisulfate-based ionic liquids show different behaviour with respect to concentration as compared to ethyl sulphate-based ionic liquids. It is significant and useful analysis for the further implementation of alkyl sulfate based ionic liquids as solvents in extraction processes. The log P values of the ethyl sulphate-based ionic liquids were noted to vary linearly with the concentration of the ionic liquid, whereas a flip-flop trend with the concentration for the log P values of the bisulphate-based ionic liquids was observed due to the difference in hydrogen bond accepting basicity and possibility of aggregate formation of these anions. The pi-pi interactions between the imidazolium and pyridinium rings were seen to affect the log P values. The alkyl chain length of anions was also observed to influence the log P values. The hydrophobicity of ionic liquid changes with the alkyl chain in the anion in the order; [HSO4](-) \< [EtSO4](-) \< [BuSO4](-).

}, issn = {1463-9076}, doi = {10.1039/c5cp06611e}, author = {Jain, Preeti and Kumar, Anil} } @article {43913, title = {Comparable ionicity of the solutions of aprotic and protic ionic liquids by anion substitution}, journal = {Journal of Solution Chemistry}, volume = {46}, year = {2017}, month = {JUN}, pages = {1-13 }, type = {Article}, abstract = {Temperature dependent molar conductances and fluidities of bisulfate and ethyl sulfate anion-based ionic liquids were measured. The extent of dissociation of the ionic liquids was estimated from the Walden plot in term of ionicity. The ionicity mainly depends on the magnitude of Coulombic forces, altered by the anion{\textquoteright}s Lewis basicity. Aqueous solutions of aprotic ionic liquids, in general, possesses ionicity in the range of ≈70{\textendash}99\%. This article reveals that the substitution of the anion by bisulfate and ethylsulfate reduces the ionicity of aqueous solution of these ionic liquids to the range of 10{\textendash}37\%. This is very close to that exhibited by some of the protic ionic liquids and phosphonium based ionic liquids with sweetner anions. The concentration dependent molar conductance of these ionic liquids has been fitted to Mahiuddin and Ismail{\textquoteright}s equation. To our surprise, the molar conductances of bisulfate-based aprotic ionic liquids are remarkably high, even though these ionic liquids possess lower ionicity.}, doi = {10.1007/s10953-017-0640-9}, author = {Jain, Preeti and Kumar, Anil} }