Abstract: A process for preparing 4-substituted 2,2,6,6-tetramethylpiperidin-N-oxy compounds (II) or mixtures of (II) and 4-substituted 2,2,6,6-tetramethylpiperidin-N-hydroxy compounds (III) where X+Y can be O or can represent a cyclic ketal with the radicals or can represent an open-chain ketal in which X?O—R and Y?O—R?, where R and R? can be identical or different and can each be CH3, CH2—CH3, CH2—CH2—CH3, CH(CH3)—CH3, CH2—CH2—CH2—CH3 and CH2—CH(CH3)—CH3, by oxidizing corresponding 4-substituted 2,2,6,6-tetramethylpiperidines (I) with hydrogen peroxide in the presence of alkali metal hydrogencarbonate and/or ammonium hydrogencarbonate and in the presence or absence of a solvent, in which the reaction is carried out with the addition of Brönsted acids which have an acid strength greater than that of the hydrogencarbonate.

Abstract: An aromatic polyamide molding compound, comprising:I. an aromatic polyamide having the basic structure ##STR1## where Ar is an aromatic radical without amine-reactive functional groups n is a number between 5 and 500; X represents --SO.sub.2 -- or --CO--, andY represents --O-- or --S--; andII. an aromatic liquid crystalline thermoplastic.

Abstract: The invention provides aromatic polyamides having an improved resistance to thermo-oxidation. This is achieved by carrying out the polycondensation in the presence of a catalyst system which comprises a mixture of a phosphorus compound and a tin(II) compound or is a compound which contains both elements. The process according to the invention allows aromatic polyamides to be obtained which are resistant to thermo-oxidation (discoloration).

Abstract: 4,4'-bis-(4-aminophenoxy)-diphenyl sulfone (BAPS) has been prepared from 4-aminophenol and a 4,4'-dihalodiphenyl sulfone in an organic solvent in the presence of an inorganic carbonate in a one-stage reaction, a pure product having a high melting point being obtained.

Abstract: 1. A polyamide molding compound, comprised of:(I) an aromatic polyamide having the structure ##STR1## where n is a number between 5 and 500; X represents --SO.sub.2 -- or --CO--, andY represents --O-- or --S--; and (II) an amorphous polyamide.

Abstract: Molding compounds based on a thermoplastically processible aromatic polyamide. Molding compounds with an improved stability toward thermal oxidation were attained in that the molding compounds in comparison to polyamides contain chemically inert compounds of the formula I ##STR1## The molding compounds according to the invention exhibit an excellent stability toward thermal oxidation.

Abstract: A thermoplastically processable aromatic polyamide is prepared by polycondensing diacid monomer A with diamine monomer B: (A) HOOC--Ar--COOH;(B) H.sub.2 N--Ar'--NH.sub.2 ; wherein Ar is 1,3-- or 1,4-phenylene; 1,4--, 1,5--, 2,6-- or 2,7-naphthylene, ##STR1## and Ar' is ##STR2## wherein X is --SO.sub.2 -- or --CO--; Y is --O-- or --S--; Z is --O--, --S--, --SO.sub.2 --, --CO-- or ##STR3## wherein R and R' each is --H or C.sub.1 -- to C.sub.4 -alkyl and n is 0 or 1 in the melt at a temperature in the range of from 200.degree. to 400.degree. C. in the presence of a catalyst selected from the group consisting of alkyl- or aryl-phosphonic acids, -phosphonous acids, -phosphinic acids, esters thereof, halides thereof and mixtures thereof, the catalyst content being 0.01 to 2.0 mol % relative to the total content of components A and B.

Abstract: Aromatic polyamides with an improved stability toward thermal oxidation was achieved by polycondensation being performed in the presence of 0.05 to 4 mol % of a catalyst comprising a mixture of phosphorus compounds and metal salts.With the process according to the invention, it is possible to obtain aromatic polyamides stable toward thermal oxidation.

Abstract: The invention provides aromatic polyamides having an improved resistance to thermo-oxidation. This is achieved by carrying out the polycondensation in the presence of a catalyst system which comprises a mixture of a phosphorus compound and a tin(II) compound or is a compound which contains both elements. The process according to the invention allows aromatic polyamides to be obtained which are resistant to thermo-oxidation (discoloration).

Abstract: High purity 4,4'-bis(4-aminophenoxy)diphenyl sulfone is prepared from p-aminophenol, alkali metal hydroxide and 4,4'-dihalodiphenyl sulfone by using a molar ratio of alkali metal hydroxide: 4-aminophenol in the range of 1.0-1.1:1.0 and a molar ratio of 4-aminophenol: 4,4'-dihalodiphenyl sulfone in the range of 2.005-2.05:1.0 and by using a dialkylamide or N-alkyl lactam as a solvent. Pristine products (no-recrystallization) of 99.0% purity having melting points above 195.degree. C. are obtained.

Abstract: The invention provides aromatic polyamides having a reduced melt viscosity which are derived from aromatic dicarboxylic acids, aromatic diamines and aromatic monocarboxylic acids being present in the polyamide in an amount of from 0.01 to 10 mol %. The invention allows molding compositions to be provided which have improved processability and good mechanical properties.