J. Indian Chern. Soc., Vol. 86, September 2009, pp. 942-949 Density, viscosity and ultrasonic velocity studies of cardo group containing symmetric double Schiff bases solutions at 303, 308 and 313 K B. J. Gangani and P. H. Parsania* Department of Chemistry, Saurashtra University, Rajkot-360 005, Gujarat, India E-mail : phparsania@aol.com; phparsania22@gmail.com Manusmpt recetved 27 May 2009, accepted 1 June 2009 Abstract : The density, viscosity and ultrasonic velocity (2 MHz) of pure solvents e.g. chloroform, DMF, 1,4-dioxane and symmetric double Schiff bases solutions have been to understand the effect of solvents on molecular interactions at 303, 308 and 313 K. Various acoustical parameters such as U (ultrasonic velocity), Z (specific acoustical Impedance), x 5 (Isentropic compressibility), R (Rao's molar sound function), b (Van der Waals constant), lt (internal pressure), Vr (free volume), Lr (intermolecular free path length), (a/f 2 >c 1 (classical absorption coefficient) and 1: (vis- cous relaxation time) have been determined and correlated with concentration (C). Good to excellent correlation be- tween a given parameter and concentration is observed at all temperatures (7') and solvent systems studied. Linear or non-linear increase or decrease of acoustical parameters with concentration and temperature indicated the existence of strong molecular Interactions. The linear or non-linear increase of Sn with C and decrease with T further supported the existence of molecular Interactions. Keywords : Ultrasonic velocity, acoustical parameters, density, viscosity, solute-solvent and solvent-solvent Interactions, Schiff bases. Introduction Theoretical equations for acoustical parameters : Specific acoustical impedance : Schiff bases are useful as fme chemicals, medical sub- strates and ligands for metal complexes and find their industrial application as antifungal and biological applications 1 -4. They are also useful for the synthesis of drugs like antibiotics, antiallergic, antiphlogistic and antitumorS- 1 2 and for dyes, liquid crystals and powerful corrosion inhibitorl3-IS. Z = Up (l) To our knowledge no work has been reported on ul- trasonic studies of symmetric double Schiff bases of l,l '- bis(4-amino phenyl)cyclohexane. The objective of the present work was to investigate the effect of concentra- tion, temperature, solvents as well as nature of Schiff bases on ultrasonic and related acoustical properties of Schiff bases (1). R R 0-= ,_oo--(j 1 SDSB-1: R = H SDSB-2 : R = 4-CH 3 942 Isentropic compressibility : l l(s = --- U2p Rao's molar sound function : R = __.!!_ u'h p (2) (3) where M is the apparent molecular weight of the solution and can be calculated according to eq. (4) : where w 1 and W 2 are weight fractions of solvent and solute, respectively; M 1 and M 2 are molecular weights of solvent and solute, respectively. Van der Waals constant: (5)