Abstract: Substituted amino aromatic compounds such as 3-amino-4-hydroxybenzoic acid are prepared by electrolytically reducing the corresponding nitro aromatic compound in a basic medium at temperatures below 60.degree. C. and current densities greater than 50 milliamps per square centimeter. The aminohydroxybenzoic acids are useful in the preparation of polybenzoxazoles which are used to make fibers and composites having high strength and thermal stability.

Abstract: The present invention relates to a new process for the preparation of phosphonic acid esters of the formula I ##STR1## in which Ar denotes phenyl, a binuclear or polynuclear aromatic radical, cycloheptatrienyl, furyl or pyridyl, X denotes (substituted) alkyl, (substituted) alkoxy or optionally substituted aryl, aryloxy, heterocyclyloxy or arylmercapto radicals, phenylcarbonylamino, alkylcarbonylamino or alkoxycarbonylamino, alkylmercapto, alkoxycarbonyloxy, alkoxycarbonylalkoxy, phenylaminocarbonyloxy or alkylaminocarbonyloxy or two radicals X in the orthoposition together form a (substituted) (C.sub.3 -C.sub.4) chain in which 2 carbon atoms can be replaced by oxygen, Y denotes halogen, alkoxycarbonyl, alkylcarbonyl, nitro, nitroso, cyano, alkylsulfonyl, phenylsulfonyl, alkoxysulfonyl, phenoxysulfonyl, alkoxy/alkylphosphinyl, halogenated alkyl, formyl or (substituted) amidosulfonyl, R denotes alkyl, n denotes 1, 2 or 3 and m denotes 0, 1, 2 or 3, wherein a compound of the formula IIX.sub.n --Ar--Y.sub.

Abstract: In the process for the anodic oxidation of mechanically, chemically and/or electrochemically roughened aluminum or of one of its alloys, an aqueous electrolyte, which is free from H.sub.2 SO.sub.4 and contains H.sub.3 PO.sub.4 and Al.sup.+3 ions is used. The process parameters are: an electrolyte content of 25 g/l to 500 g/l of H.sub.3 PO.sub.4 and at least 5 g/l of Al.sup.+3 ions, a treatment time of 5 seconds to 500 seconds, a current density of 1 A/dm.sup.2 to 30 A/dm.sup.2 and a temperature of 35.degree. C. to 95.degree. C. The Al.sup.+3 ion source in particular is a salt of aluminum having a phosphoroxo anion, such as AlPO.sub.4. The material prepared in accordance with this invention is preferably employed as a support material for offset printing plates which carry a radiation-sensitive layer.

Abstract: Less co-dissolution of silver results when base metal-containing deposits on the surfaces of silver objects are dissolved off with sulphuric or phosphoric acid, rather than hydrochloric acid.

Abstract: An electrolytic cell comprises an anode and a cathode which are partitioned by an ion exchange membrane having at least one roughened surface which contacts with or closes in a distance of up to 20 mm to a corresponding electrode.