International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611 Volume 5 Issue 1, January 2016 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Conductometric Study of Substitutedthiocarbamidonaphthols in 70% Ethanol– Water Mixture at Different Molar Concentrations at Constant Temperature A. B. Wadekar 1 , D. T. Tayade 2 1 Department of Chemistry, S.D.M. Burungale Science College Shegaon Dist. Buldhana, Maharashtra, India 2 Department of Chemistry, GVISH, Amravati 444 604. Maharashtra, India Abstract: Recently in this laboratory conductrometric investigation of 5-phenylthiocarbamido-1-naphthol, 5-p- chlorophenylthiocarbamido-1-naphthol and 5-p-tolylthiocarbamido-1-naphthol, have been carried out at different concentrations of solute in 70% ethanol-water mixture at constant temperature. G, K and µ values are determined. The thermodynamic parameters viz. ΔH, ΔS and ∆G for the ion pair formation determine from the value of ion association constant at constant temperature. This investigation provided valuable information regarding to solute-solvents, solute–solute and solvent-solvent interaction, effect of various substituent’s of drugs and effect of dilution from the present conductometric measurements. Keywords: Thermodynamic parameters, 5-phenylthiocarbamido-1-naphthol [PTCN], 5-p-chlorophenylthiocarbamido-1-naphthol [p- CPTCN] and 5-p-tolylthiocarbamido-1-naphthol [p-MPTCN]. 1. Introduction Number of ions of electrolyte in solution decide the conduction of electrolytic solution. Conductrometric measurements of electrolytic solution provided valuable information concerned to solubility and permeability of drugs, which are essential biopharmaceutical parameters. These two parameters are accountable for effective bioavailability and good in vitro and vivo correlation [1]. Now-a-days pharmaceutical technologist has great challenge to enhance the solubility and dissociation rate and oral bioavailability of weakly water soluble drugs[2]. Hydrot ropic solubalisation is considered as one of the sophisticated methods of solubalisation[3] Enhance the aqueous solubalisation of insoluble drugs by adding hydrotropic agents. Number of researchers work on the effect of solubility enhancers[4]-[5] and due to that increase solubility of drugs but no detail explanation available regarding to these improving solubility. `The split of electrolyte conductivities into the ionic components ideally requires transference numbers, the accurate measurements of which present serious experimental problems in many non-aqueous solvents. Conductometric measurments provided valuable information about solute-solute and solute-solvent interaction[6]. Conductrometrically investigation of the ionic association of divalent asymmetric electrolyte Cu(NO 3 ) 2 with Kryptofix-22 in mixed (MeOH-DMF) solvents at different temperatures was carried out by Gomma and Al-Jahdalli[7]. Many researchers were studied the alkali metal at different proportion of mixed solvents by conductometrically[8]-[9]. Very few researchers investigated the thermodynamic parameter and Walden product of different complexes and they also examine the comparison of transition metal complexes among the halide group[10]-[14]. Singh et al[15] was investigated the ion pair formation and thermodynamic parameters of Glycine Bis-1-amidino-O-methylurea Co(III) halides in water-methanol mixture at different temperatures 15 . Conductometric study of nimesulide in aqueous solutions of hydrotropic agents at different temperatures was carried out by solanki et al[16]. Present work concern to investigation of conductometric properties, thermodynamic behavior and Walden product of 5-phenylthiocarbamido-1-naphthol, 5-p-chlorophenylthio- carbamido-1-naphthol and 5-p-tolylthiocarbamido-1- naphthol in 70% ethanol-water mixture at different concentration and at constant temperature i.e. 298K. Shedlovsky method[17] used for the data analysis. Recently observed values of association constant at various concentrations which help to examine the thermodynamic parameters like ∆H, ∆S and ∆G for the formation. Resultant values help to examine the nature of different interactions. 2. Experimental In present investigation used all the freshly prepared solution. All the chemicals and solvents used for the synthesis were of A.R. grade. The solvents were purified by standard method. Prepared different concentration solutions of 5-phenylthiocarbamido-1-naphthol, 5-p-chlorophenylthio caraamido-1-naphthol and 5-p-tolylthiocarb amido-1- naphthol viz. 0.01M, 0.005M. 0.0025M and 0.0012M by using 70% ethanol-water mixture. Maintain the thermal equilibrium (298K) of drugs solution by using thermostat. After getting thermal equilibrium, conductivity of that electrolyte was measured. 3. Result and Discussion Firstly prepared the solution of 0.01 M concentration then by the serial dilution method prepared the solutions of 0.005M, Paper ID: NOV152805 678