Dynamit Nobel Aktiengesellschaft

Gunther Meyer

Klaus-Dieter Steffen

Klaus Thewalt

Hans-Joachim Herrmann

Reinhard Schmidt

Gerhard Bier

Otto Ackermann

Rudolf Burkhardt

Hans Leuck

Fritz Englander

Gerhard Schmeling

Wilhelm Gresser

Siegmund Frick

Paul Janssen, Deceased

A method for the preparation of 3,4-dihydro-alpha-pyrones by the thermolysis of 5-hydroxymethyl-gamma-butyrolactone in a liquid medium at temperatures between 300.degree. and 400.degree. C. and in the presence of aluminosilicates as catalysts is disclosed. The dihydropyrone that forms is distilled out of the reaction medium together with the reaction water immediately after its formation. Heat transfer oils, including, for example, polynuclear aromatic compounds joined together by methylene bridges or other bridge groupings, are especially suitable as heat transfer oils. The method has the advantage of permitting the temperature to be regulated within a definable range so that secondary reactions due to local overheating or imprecise temperature control occur to only a limited degree if at all.

Method of preparing 3,4-dihydro-alpha-pyrones

A process for the continuous production of an alkali metal alcoholate of a higher alcohol which comprises continuously introducing a higher alcohol into a reaction vessel, continuously introducing an alkali metal alcoholate of a lower alcohol into said reaction vessel and continuously and simultaneously distilling over and removing from said reaction vessel lower alcohol which forms.

Method for the continuous preparation of alcoholates

An aromatic polyazomethine of the structural formula ##STR1## wherein R represents hydrogen, halogen, alkyl or alkoxy,

Polymeric azomethines

An aromatic bisazomethine prepared from the disubstituted benzidines and aromatic aldehydes, characterized by the general formula ##STR1## wherein each R=COOCH.sub.3, COOC.sub.2 H.sub.5, COOH, CH.sub.2 Cl, CHCl.sub.2, CH.sub.2 Br, CCl.sub.3, Cl or Br and

Aromatic bisazomethines, a method for their preparation, and their use

Oligomeric alkylene terephthalates having an average degree of condensation of 4 to 7 are produced by passing dimethylterephthalate and diol having at least 3 carbon atoms downwardly through a series of reaction chambers, each outfitted with stirring and heating means employed so that the temperature increases from stage to stage. Thereby transeterification is effected. The chambers are interconnected so that the methanol evolved in each chamber is vented without being admixed with the material undergoing transesterification in any of the other chambers. The transesterification product is then condensed at elevated temperature and under vacuum to produce the oligomer. The oligomers are high reactivity so that the further condensation thereof to polyesters is simplified.

Method for the preparation of oligomeric alkylene terephthalates

An improvement in the method of preparing a linear polycondensate of high molecular weight wherein a precondensate is initially formed and thereafter subjected to a one-step melt condensation in a vacuum while cleavage products are removed therefrom, the reaction mass being exposed in a thin layer by means of a stirrer to the reaction conditions, the improvement residing in employing as the precondensate a molten precondensate having an average condensation degree of at least 3, said precondensate being introduced into the melt condensation zone continuously while the cleavage products are driven off at the particular optimum, product-specific condensation temperature, the contents of the melt condensation zone being subjected to the action of a rotary stirrer until the melt has a melt viscosity of 1000 to 15000 poises and continuously withdrawing molten polycondensate in accordance with the speed of the reaction. Also disclosed is an apparatus in which the polycondensation is effected including an offset withdrawal outlet containing an auger which can enter a funnel disposed between the outlet and the polycondensation zone. Also disclosed is an upright multi-chamber vessel in which the precondensate is formed wherein the chambers are disposed one over the other. Some of the upper chambers are equipped with means for maintaining a normal or elevated pressure while some of the lower chambers are equipped with means for imposing a partial vacuum on the contents.

Preparation of polycondensate by one-step melt condensation in a vacuum

Vinyl fluoride having an impurities content of less than 100 parts per million; a method of preparing vinyl fluoride with an impurities content of less than 100 parts per million which comprises contacting gaseous vinyl fluoride with a finely divided copper containing catalyst composition at a temperature of between 0.degree. and 100.degree. C.; a polyvinyl fluoride organosol having an organosol viscosity, determined in a 40 wt.% suspension in propylene carbonate of 20 to 100 cP; a method of producing a polyvinyl fluoride which when suspended in a suspension in polypropylene carbonate in an amount of 40 wt.% has an organosol viscosity of about 20 to 100 cP. which comprises heating vinyl fluoride in an aqueous medium containing a water soluble azo initiator at a pressure less than 140 kp./cm.sup.2 at a temperature of 60.degree.-85.degree. C.

Process for purifying vinyl fluoride

Polyvinylchloride inhibited against release of hydrogen chloride at elevated temperature is produced by polymerizing vinyl chloride in a reaction medium having finely divided calcium carbonate dispersed therein.

Growing community of inventors

Troisdorf-Sieglar, Germany

Gunther Meyer