Abstract: Production of methyldichlorophosphane. The compound is made by reacting methane and phosphorus trichloride in a reaction zone in which a temperature higher than 500.degree. C is maintained. More specifically, hot reaction gas coming from the reaction zone is mechanically freed from solid matter, and the reaction gas freed from solid matter is passed to a quenching zone in which it is quenched with liquefied reaction mixture having 0.3 to 5 weight % of an organic barium compound or a non-ionic surfactant dissolved therein.

Abstract: A distillation column comprising a shell which has serially arranged therein a plurality of distilling trays with respective liquid inlets and outlets. An annular slit of substantially uniform width is left between the individual trays and the shell. The slit may be interrupted by a plurality of spacers which bear against the inner surface of the shell, and the spacers are provided around the periphery of the individual trays.

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.