As solvents at early stages of development of processes of selective purification of oils aniline, nitrobenzene, liquid sulphurous anhydride, etc. were used. Now the main industrial solvents are phenol, furfural and N-metylpyrolidon finding the increasing application. The possibility of phenol replacement on N-metylpyrolidon was described in the article
N-metylpyrolidon, phenol, oils, production of oils.