Process for the purification of high-melting organic products

US4141799A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Bernd Thelen · Leverkusen, DE
• Hans-Walter Brandt · Odenthal, DE
• Wolfgang Auge
• Karl-Werner Thiem · Charleston, US

Key dates

• Filing date: Aug 12, 1977
• Grant date: Feb 27, 1979
• Expiry date: Aug 12, 1997

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C50/34
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

The purification of high-melting organic products, such an anthraquinone and substituted anthraquinones, which is substantially free from lower-boiling impurities, by melting the product to be purified by heating, while mechanically conveying the same along a path with a screw conveyer, as for example, in a melting screw; degassing the melt at a reduced pressure in a column, as for example, at a pressure of 50 to 400 mm Hg; passing the degassed melt through a thin film evaporator at a reduced pressure of, for example, 5 to 250 mm Hg to evaporate the high-melting organic product and discharging the remaining high-boiling impurities and such impurities which are not capable of being distilled from the evaporator through a conically tapering sump, while mechanically scraping residue from the sump wall, preferably with the use of a rotating helical screw in the sump; the discharge from the sump being effected into and through an enclosed path at a rate sufficient to prevent liquid accumulating in the sump, while maintaining the central portion of the enclosed discharge path at a lower temperature than its end portion to form a crystal sludge in the central portion, which acts as a pres…