Density, viscosity, and refractive index measurements of pure formamide and of formic, acetic, and propionic acids in the temperature range (298.15 to 313.15) K were made. Additionally, measurements of the same properties and in the same temperature range were made on the following mixtures: formamide + (formic acid, or + acetic acid, or + propionic acid). The results were fitted to empirical equations, whose calculated values are in agreement with the experimental ones.

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Liquid−liquid equilibrium data for the system water + ethanol + citral (neral + geranial + impurities) at 303.15 K were obtained, considering that citral is composed by two geometrical isomers along with a complex mixture of impurities. All organic chemicals contained in the commercial citral were quantified by gas chromatography using a flame ionization detector rather than a thermal conductivity detector. Moreover, this last detector was used to quantify water and ethanol. To obtain the equilibrium data for this system, several mixtures that contain different ratios of the compounds, two with different ratios of (water + ethanol), one with the (neral + geranial) ratio corresponding to the commercial citral, and two with different ratios of (citral + ethanol), were studied. The influence of the equilibrium concentrations of ethanol and water on the neral and geranial distribution was also studied. Experimental results show that ethanol enhances the solubility of citral in water.

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