Deasphalting is an alternative to distillation. Just like distillation, deasphalting fractionates different components from a feed stock. Unlike distillation, the fractionation is done by using a solvent extraction process with deasphalting. This process is more often used for vacuum distillation residue.  The highest molecular weight compounds (known as asphaltene,) found in vacuum distillation residue can be separated by precipitation once a light paraffin solvent is mixed with the feed stock in an aromatic solvent like toluene. The portion of the feedstock that is soluble in a paraffin solvent is called maltenes. Maltenes can be separated using paraffin solvents like n-heptane. Using n-pentane solvents, which are lighter and weaker, we can fractionate these compounds further. These are separated into hard resin and n-pentane soluble fractions. Using propane, we can further refine the soluble fractions.  Lighter solvents can be used to further separate the feedstock. This process is important because it allows us to separate products based on demand.

In order to understand how asphaltenes can be separated out of a vacuum distillation residue utilizing the solvent extraction method, we must understand the Hildebrand Solubility Parameters (HSP) for non-polar solvents. The Hildebrand Solubility Parameters measure the strength of the solvent that is used for extraction. There are two definitions of HSP. Each are a function of molar volume, but the first definition has a variable of surface tension, where the second definition has a variable of energy of vaporization.  Using these equations we can explain how a large volume paraffin solvent can disrupt the gradient solubility of asphaltenes to allow for the solid particles precipitate and then filtered.