Chemie Linz Gesellschaft M.b.h.

Dsm Chemie Linz Gmbh

Kurt A Hackl

Heinz Falk

Gerhard Stern

Martin Mullner

Erich Schulz

Josef Schaller

Markus Rossler

Martin M Ullner

Markus R Ossler

Process for the preparation of pure (S,S)-N-(1-ethoxycarbonyl-3-phenylpropyl) alanine,in which impure (S,S)-N-(1-ethoxycarbonyl-3-phenylpropyl)alanine is suspended in water, dissolved by heating to the boiling point and separated from insoluble impurities by filtration and the desired end product is then precipitated by cooling, filtered off and dried.

Process for the preparation of pure

A process for the dissolution of chemical compounds by use of ureas in which at least one of the urea's two nitrogen atoms is part of a non-aromatic ring which can be broken by an oxygen or sulphur atom as a chemical solvent, and a method of producing tri- or tetraalkylated ureas or bis ureas wherein at least one of the urea's nitrogen atoms is part of a non-aromatic ring which can be broken by an oxygen or sulphur atom by means of dialkylating the --NH.sub.2 group of a urea with an alkene or alkene arylene alkene dihalogenide, disulphonate or dihydrogen sulphonate in the presence of a solid base and a phase-transfer catalyst.

Method for the production of N-cyclic and N,N'-dicyclic ureas and their

A process for the preparation of isocyanic acid, characterized in that N,N-disubstituted ureas are decomposed at elevated temperature to a secondary amine of lower volatility and to isocyanic acid, which is drawn off at the top.

Process for the preparation of isocyanic acid by the decomposition of

Process for the preparation of very pure ureas of the formula phenyl--(NH--CO--NR.sub.1 R.sub.2).sub.n in which phenyl represents an unsubstituted or substituted phenyl or phenylene group and R.sub.1 and R.sub.2 are either identical and each represent an alkyl group, or are different, in which case R.sub.1 represents a hydrogen atom and R.sub.2 represents an alkyl or phenyl group, or R.sub.1 and R.sub.2, together with the nitrogen atom, represent an aliphatic heterocyclic ring and n is the number 1 or 2, by reacting a phenylurea of the formula phenyl--(NH--CO--NH.sub.2).sub.n with an amine of the formula NR.sub.1 R.sub.2 H at temperatures from 100 to 200.degree. C. in a diluent which is inert under the reaction conditions, the reaction being interrupted before by-products are formed, and the urea which is formed being removed from the starting compounds, and the unreacted starting compounds being returned to the process if appropriate.

Process for the preparation of pure N,N'-asymmetrically substituted

Process for the N-alkylation of ureas by reacting a urea with an alkylating agent in the presence of a solid base and a phase transfer catalyst in a diluent.

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Linz, Austria

Kurt A Hackl