Abstract: The invention relates to a process for removing naphthoquinone from phthalic anhydride produced by the air oxidation of naphthalene or mixtures containing naphthalene. Specifically, crude phthalic anhydride containing naphthoquinone is treated at a temperature of 180.degree.-280.degree. C. with an unsaturated aliphatic oil produced by the polymerization of 1,3-dienes and optionally isomerized having a molecular weight of 800-5,000, and optionally in the presence of 1-40 ppm of alkali ions, relative to the crude phthalic anhydride.

Abstract: The object of the invention is a process for the production of flat varnishes based on powder coatings of 1,2-epoxy compounds with at least one 1,2-epoxy group in the molecule and a lower melting point of >40.degree. C., salts of aromatic carboxylic acids with 3 and more carboxyl groups and imidazolines as curing agents, as well as the usual additives and the application of the powdered varnish upon the objects to be varnished and heating of these objects to temperatures of 160.degree.-240.degree. C., whereby the salt of 2-phenyl-methyl-.DELTA.2-imidazoline and trimellitic acid is substituted up to 60 mole % by a salt of 2-phenyl-.DELTA.2-imidazoline and trimellitic acid.

Abstract: Terpolymers of maleic anhydride, dicyclopentadiene, and a vinylcyclohexene, preferably 1-vinylcyclohexene-3, are highly effective paper sizing materials.

Abstract: A process for the fractional desublimation of pyromellitic acid dianhydride in the form of free-flowing crystals which comprises reducing a reaction gas containing pyromellitic acid dianhydride produced by a chemical reaction which also produces by-products, to a temperature above the thaw point of the by-products but below the desublimation point of pyromellitic acid dianhydride by means of a smooth thermostaticized cooling surface, directing the reaction gases at maximal flow velocities of 3 m/sec parallelly to the cooling surface and separating the fraction of crystals not adhering to the surface.

Abstract: An apparatus for recovering higher melting organic materials which is an upright column containing a gas inlet at a lower portion thereof and a gas outlet at the upper portion thereof. The apparatus has a wall disposed in the flow of the gas between the gas inlet and the gas outlet which wall is perforated to allow gas to flow therethrough. Cooling means are provided on the side of the wall away from the gas inlet to cool components of a gas flowing therethrough.

Abstract: Maleic acid is recovered from aqueous solutions containing benzoquinone especially from a catalyst benzene oxidation process by:A. concentrating an aqueous maleic acid solution containing benzoquinone;B. adding from 0.1 to 2.0 weight percent of phthalic acid or its anhydride, based on the weight of maleic acid, to the concentrated solution from (a); thereafterC. separating the maleic acid from the mixture from (b) by continuous distillation with an organic solvent and purifying the separated maleic acid.