Quantum and molecular mechanics methods were used to guide the development of a liquid extraction process for the removal of sulfur compounds from gasoline using an aqueous solvent containing n-butylamine (NBA). The calculational results suggest that the extraction mechanism was via forming micelles of NBA around single sulfur compounds. That is, micelles containing 6 to 192 molecules of NBA yielded negative formation energies. With increasing NBA amounts over the same range, total sulfur removal increased in extraction experiments. However, not all sulfur compounds were extracted simultaneously. Extraction selectivities were correlated to calculated formation energies between individual sulfur compounds and a single molecule of NBA. This suggests that extraction selectivity depended on attraction of each sulfur compound out of the gasoline to the NBA micelle wall. To provide sufficient extraction time, the number of extraction stages was investigated. The results predicted that about 10 theoretical stages would be required to achieve equal extractions of all sulfur compound types and 99 + % total sulfur removal.