This paper describes a method for predicting constants in the equation of state (EOS) for saturated and compressed refrigerant fluids from analysis of speed of sound results and using two scaling constants. The theoretical EOS is that of Song and Mason, which is based on statistical−mechanical perturbation theory, and the two constants are enthalpy of vaporization ΔH vap and molar density ρnb, both at the normal boiling temperature. The following three temperature-dependent quantities are required to use the EOS:  the second virial coefficient B 2(T), an effective van der Waals covolume, b(T), and a correction factor, α(T). The second virial coefficients are calculated from a two-parameter corresponding states correlation, which is obtained from a speed of sound data analysis with the two constants ΔH vap and ρnb as scaling parameters. b(T) and α(T) can also be calculated from second virial coefficients by scaling rules. This EOS is applied to six refrigerants:  1,1-dichloro-2,2,2-trifluoroethane (R123), 1,1,1,2-tetrafluoroethane (R134a), 1,1-dichloro-1-fluoroethane (R141b), 1,1-difluoroethane (R152a), chlorodifluoromethane (R22), and difluoromethane (R32). The results show that the liquidlike densities of these refrigerants at the temperature range 0.8T nb < T < 1.1T c can be predicted to within 3%.

An efficient synthesis of 2,4‐diaryl‐9H‐pyrido[2,3‐b] indole derivatives in aqueous medium via the three‐component reaction of indolin‐2‐one, a chalcone and ammonium acetate was developed using Na2SiO3, K2SiO3, Li2SiO3, CaSiO3, MgSiO3, BaSiO3, SrSiO3, and ZnSiO3 as catalysts. Results of activity evaluations indicated that among of the metal silicate used alkali metal silicates exhibits much higher activity than other samples due to the stronger basicity power and higher solubility in water. Under the optimum reaction conditions, all of the reactions with diverse aromatic aldehydes provided high yields in low reaction times.

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A highly efficient catalytic preparation of 2-amino-5-oxo-4-aryl-4,5-dihydroindeno[1,2-b]pyran-3-carbonitrile derivatives using different metal silicates was developed through a three-component reaction of malononitrile, aromatic aldehydes, and 1,3-indandione in high yields.

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