01862nas a2200169 4500008004100000022001400041245006200055210006100117260011000178300001400288490000700302520122500309100002501534700002601559700001601585856009101601 2012 eng d a1463-907600aDo anions influence the polarity of protic ionic liquids?0 aDo anions influence the polarity of protic ionic liquids aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcDEC a2754-27610 v143 a

Polarity studies in two classes of imidazolium-based protic ionic liquids (PILs) possessing [HSO4](-), [HCOO](-),[CH3COO](-) and [CH3CH2COO](-) anions were carried out using a solvatochromic method from 298.15 to 353.15 K. For 1-methylimidazolium class of PILs, ET(30) was found to be independent over the entire range of temperature, while ET(30) was noted to decrease with a rise in temperature in the case of 1-butylimidazolium class of PILs containing [CH3COO](-) and [CH3CH2COO](-) anions. The ET(30) value decreases in both the classes upon varying the anions ([HSO4](-), [HCOO](-), [CH3COO](-) and [CH3CH2COO](-)). The E-T(30) value is controlled by hydrogen bond acceptor basicity, b, and dipolarity/polarizability, pi*. The E-T(30) value for PILs varies inversely to the strength of the coulombic interaction between ions in PILs. Strong interactions between ions lead to lower E-T(30) values. Unlike the poor thermal effect on E-T(30), the Kamlet-Taft parameters i.e. alpha, beta and pi* have pronounced thermal effect in the imidazolium-based PILs. Variation in the Kamlet-Taft parameters is controlled by the stabilization of ions and the degree of proton transfer from Bronsted acid to Bronsted base.

1 aShukla, Shashi, Kant1 aKhupse, Nageshwar, D.1 aKumar, Anil uhttps://library.ncl.res.in/content/do-anions-influence-polarity-protic-ionic-liquids-001318nas a2200157 4500008004100000022001400041245010300055210006900158260007300227300001000300490000800310520067700318100002500995700001601020856012401036 2013 eng d a0009-261400aDo protic ionic liquids and water display analogous behavior in terms of hammett acidity function?0 aDo protic ionic liquids and water display analogous behavior in  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR a12-160 v5663 a

We address an issue whether the strength of carboxylic acids in water is linear with respect to that in ionic liquids. Strength of carboxylic acids in water and different PILs using Hammett function (Ho) has revealed interesting linear correlation between the Ho function for all acids in PILs and PIL-water in spite of large structural and electronic differences. These observations suggest that different structural and electronic features of PILs and water behave analogously towards Ho. This linearity in Ho functions between PILs and PIL-water systems can be used to develop predictive method to calculate Ho values. (c) 2013 Elsevier B.V. All rights reserved.

1 aShukla, Shashi, Kant1 aKumar, Anil uhttps://library.ncl.res.in/content/do-protic-ionic-liquids-and-water-display-analogous-behavior-terms-hammett-acidity-002303nas a2200157 4500008004100000022001400041245011500055210006900170260007100239300001400310490000800324520164600332100002501978700001602003856012602019 2015 eng d a1520-610600aDissociation of equimolar mixtures of aqueous carboxylic acids in ionic liquids: role of specific interactions0 aDissociation of equimolar mixtures of aqueous carboxylic acids i a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR a5537-55450 v1193 a

Hammett acidity function observes the effect of protonation/deprotonation on the optical density/absorbance of spectrophotometric indicator. In this work, the Hammett acidity, H-0, of equirriolar mixtures of aqueous HCOQH, CH3COOH, and CH3CH2COOH was measured in 1-methylimidazolium-, 1-methylpyrrolidinium-, and 1-methylpiperidinium-based protic ionic liquids (PILs) and 1-buty1-3-methylimidazolium-based aprotic ionic liquid (AIL), with formate (HCOO-) anion. Higher H-0 values were observed for the equimolar mixtures of aqueous carboxylic acids in protic ionic liquids compared with those of the aprotic ionic liquid because of the involvement of the stronger specific interactions between the conjugate acid of ionic liquid and conjugate base of carboxylic acids as suggested by the hard soft acid base (HSAB) theory. The different Ho values for the equimolar mixtures of aqueous carboxylic acids in protic and aprotic ionic liquids were noted to depend on the activation energy of proton transfer (E-a,H(+)). The higher activation energy of proton transfer was obtained in AIL indicating lower ability to form specific interactions with solute than that of PILs. Thermodynamic parameters determined by the ``indicator overlapping method'' further confirmed the involvement of the secondary interactions in the dissociation of carboxylic acids. On the basis of the thermodynamic parameter values, the potential of different ionic liquids in the dissociation of carboxylic acids was observed to depend on the hydrogen bond donor acidity (alpha) and hydrogen bond acceptor basicity (beta), characteristics of specific interactions.

1 aShukla, Shashi, Kant1 aKumar, Anil uhttps://library.ncl.res.in/content/dissociation-equimolar-mixtures-aqueous-carboxylic-acids-ionic-liquids-role-specific-1