Abstract: A process for purifying phosphorus chelate ligands by extraction, by using polar extractants.

Abstract: A reactor for the thermal cleavage of monofunctional and/or polyfunctional carbamic esters into the corresponding isocyanate and hydroxyl components in the liquid phase having devices for introduction of heat into the reactor, where the devices are heat exchanger plates through which a heat transfer medium flows and have a geometry defined by the ratio of the degassing area to the volume and arrangement of the heating surfaces which makes it possible for the cleavage to be carried out in a two-phase mixture which has a gas content of over 50% by volume.

Abstract: The present invention relates to a process for the dissociation of allophanates, in which a thermal dissociation is carried out in a reaction vessel and the gaseous dissociation products obtained are removed from the reaction vessel using an inert carrier gas or the vapor of a liquid as stripping medium and are condensed.

Abstract: The present invention relates to a process for the dissociation of allophanates, in which a thermal dissociation is carried out in a reaction vessel and the gaseous dissociation products obtained are removed from the reaction vessel using an inert carrier gas or the vapor of a liquid as stripping medium and are condensed.

Abstract: Organic polyisocyanates are prepared by a process in which polyurethanes are thermally dissociated in a dissociation reactor, a distillation is subsequently carried out and the bottom fraction obtained here is recirculated, wherein the recirculated bottom fraction is firstly fed at least partly into a reaction region and subsequently into the dissociation reactor.

Abstract: A very pure aqueous solution of free hydroxylamine is prepared by a process in which the dilute, aqueous hydroxylamine solution is concentrated in a column by removing hydroxylamine-containing vapors via a side take-off in the bottom of the column, and very pure hydroxylamine is obtained by condensing the vapors. The novel process can be carried out simply, in a gentle manner and on a large scale and gives electronic grade hydroxylamine.

Abstract: A process for purifying crude pyrroles obtained in the preparation of pyrroles of the general formula I ##STR1## where R is hydrogen or a C.sub.1 -C.sub.6 -alkyl radical, which comprises treating the mixture containing the crude pyrrole with an acid or an activated carboxylic acid derivative and removing the pyrrole from the mixture by distillation at reduced pressure and at a bottom temperature of up to 160.degree. C.