Desired Properties of Petroleum Solvents

The essential properties of the various types of solvents are related to the following characteristics  

Volatility is one of the most important properties of a hydrocarbon solvent. Volatility has a direct relation to the time it takes to evaporate the solvent and, therefore, to the drying time for the dissolved product. The desired value of volatility varies greatly with the nature of the dissolved product and its application temperature. Therefore, whether it be an ink that needs to dry at ambient temperature, sometimes very fast, or whether it be an extraction solvent, the volatility needs are not the same. 

Volatility is generally characterized by a distillation curve (the quantity distilled as a function of temperature). Often, only the initial and final boiling points are taken into account along with, possibly, a few intermediary points. 

Another measurement characterizing volatility is that of vapor pressure. 

Solvent power characterizes the miscibility of solute and solvent. This concept covers two types of uses dissolving a solid or reducing the viscosity of a liquid. The solvent power should be as high as possible. However, a solvent used as an extractant should also be selective, i.e., extract certain substances preferentially from the feed being treated. 

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