Distillative purification of 2,5-dioxo-1-oxa-2-phospholanes

US4016048A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Klaus Gehrmann · Lechenich, DE
• Alexander Ohorodnik · Lechenich, DE
• Elmar Lohmar
• Wernfried Riechmann

Key dates

• Filing date: Jul 13, 1976
• Grant date: Apr 5, 1977
• Expiry date: Jul 13, 1996

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S203/11
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

2,5 DIOXO-1-OXA-2-PHOSPHOLANES OF THE GENERAL FORMULA: ##STR1## in which R.sup.1 stands for an alkyl radical having from 1 to 4 carbon atoms, or a phenyl radical, and R.sup.2 and R.sup.3 each stand for hydrogen or CH.sub.3, are distillatively purified. To this end the respective crude compound is preheated to 120.degree. to 160.degree. C and fed to the head of a distilling column provided with a plurality of individually heatable trays maintained at temperatures increasing from the upper-most tray to the lowermost, the uppermost tray in the column being maintained at 120.degree. to 160.degree. C and the lowermost tray being maintained at 160.degree. to 200.degree. C, the pressure at the head of the column being 20 to 200 mm Hg, preferably 50 to 120 mm Hg; an inert gas preheated to 160.degree. to 200.degree. C is introduced countercurrently at the base of the column; those impurities having a boiling point lower than that of the respective 2,5-dioxo-1-oxa-2-phospholane are withdrawn overhead together with the inert gas; the 2,5-dioxo-1-oxa-2-phospholane thus freed from low-boiling impurities is withdrawn from the base of the distilling column and passed to a film evaporator; and the…