Abstract: There is disclosed an azeotropic distillation process for separating and recovering hexamethyl disiloxane (HMDO) from toluene in a spent liquor mixture. An HMDO azeotrope former, pyrrolidone, is added to the liquor. The pyrrolidine is added in an amount of at least about 1.81 parts by weight per 1.0 part by weight of HMDO. Preferably, it is added in excess, as about 2.7 to about 5.4 parts by weight of pyrrolidine per 1.0 part by weight of HMDO. The resulting azeotrope of HMDO and pyrrolidine is then separated by distillation from the liquor. The pyrrolidine may be subsequently recovered from the HMDO by extraction with water. Other HMDO azeotrope formers, such as tertiary butanol, may also be utilized.

Abstract: There is disclosed an azeotropic distillation process for separating toluene from methyl isobutyl ketone (MIBK) in a spent liquor mixture. A toluene azeotrope former, preferably methanol, is added to the liquor in an amount sufficient to form an azeotrope with all of the toluene present in the mixture. The methanol is added in an amount of at least about 2.62, typically an excess amount of about 3.4 to about 6.3 parts by weight of methanol per 1.0 part by weight of toluene. The resulting azeotrope of methanol and toluene is then separated by distillation from the MIBK. The methanol may be subsequently recovered from the toluene by extraction with water. Other toluene azeotrope formers may be utilized.