N,N-Dimethylaniline and n-hexane used were of AnalaR grade (MERCK) samples, with the estimated purity of > 99%. o-cresol, m-cresol and p-cresol were of AR grade samples (purity > 98%) supplied by SD Fine-Chemicals, India. The suppliers of these compounds, the purification method and method of analysis of estimated purity are summarized in Table 1. The mass fraction purity of the liquids and the purification methods are given in Table 1. All the liquid mixtures were prepared by weighing appropriate amounts of pure liquids and mixed in airtight stoppered bottles to minimize Erlotinib Hydrochloride losses. The values of ultrasonic velocity and density of pure components required to calculate the acoustical properties and formation constant of the complex are available in literature , , , ,  and  and those values were used in our calculations. The density, ρ of the ternary systems was determined by using a 10 ml specific gravity bottle. All the weighing measurements were made with a parietal lobe digital balance (Shimadzu, Japan) of accuracy ± 0.1 mg. The accuracy of the concentration (mol kg− 1) was ± 1 × 10− 3. The ultrasonic velocities of the ternary liquid mixtures were measured using a single crystal variable path ultrasonic interferometer operating at 2 MHz frequency supplied by Mittal Enterprises, New Delhi, India, Model F81, with an accuracy of ± 1 ms− 1. Viscosity measurements were made with an Ostwald's viscometer in which the flow time for solutions was measured with a digital stop clock of accuracy ± 0.01 s. The temperature of the sample was maintained constant to an accuracy of ± 0.1 K by digitally controlled thermostatic water bath. The results of velocity u, density ρ and viscosity η summarized in Table 2 represent the average of at least five independent measurements for each composition of the ternary liquid mixtures.