Abstract: The chromic anhydride contained in soluble form (chromic acid) in exhausted, polluted chromium plating baths is recovered by alkalizing the exhausted chromium plating liquid to a pH comprised between 3 and 7 at a temperature of 70.degree. C. with a commercial sodium hydroxide solution, keeping the mass in reaction at this temperature for an hour and filtration separating the precipitate obtained. The filtered solution having a specific gravity of 1.25 kg/l, contains CrO.sub.3 (22% in weight) which is then reduced with sulphur dioxide to obtain a solution containing basic chromium sulphate and sodium sulphate, suitable for use as a tanning bath; in this manner pollution is avoided and the waste chromium is exploited. The solution containing CrO.sub.3 can also be introduced into a hexavalent chromium salt production cycle.

Abstract: An adduct of menadione and thiamine is described having the general formula C.sub.34 H.sub.36 N.sub.4 O.sub.11 S.sub.3, molecular weight 772.84 and containing the components in a molecular ratio of 2:1 respectively.This adduct is particularly intended to be added to integrator mixtures for zootechny.

Abstract: A tanning material solution, containing both basic chromic sulfate and quinone groups, to which mercaptoacetic acid as a quinone hindering corrective is previously added.

Abstract: This invention relates to a two stage process for preparing 2,6-pyridinedicarboxylic acid or dipicolinic acid from 2,6-dimethyl-pyridine through oxidation of the latter in an acid environment with hexavalent chromium salts and formation of a molar addition compound between dicarboxylic acid, being formed by oxidation, and chromic anhydride in the first stage, and subsequent hot hydrolysis of the addition product so obtained, thus isolating 2,6-pyridinedicarboxylic acid therefrom in the second stage. The invention also comprises the above mentioned intermediate complex addition compound and the 2,6-pyridinedicarboxylic acid of high purity, obtained by the process according to said invention.

Abstract: This invention relates to a two stage process for preparing 2,6-pyridin-dicarboxylic acid or dipicolinic acid from 2,6-dimethyl-pyridine through oxidation of the latter in an acid environment with hexavalent chromium salts and formation of a molar addition compound between dicarboxylic acid, being formed by oxidation, and chromic anhydride in the first stage, and subsequent hot hydrolysis of the addition product so obtained, thus isolating 2,6-pyridin-dicarboxylic acid therefrom in the second stage. The invention also comprises the above mentioned intermediate complex addition compound and the 2,6-pyridin-dicarboxylic acid of high purity, obtained by the process according to said invention.

Abstract: A highly selective oxidation process for preparing pyridin-carboxylic acids from pyridine compounds nucleus substituted with alkyl groups, through a carbon-carbon bond, and oxidizable to carboxyl, and from hydrosoluble hexavalent chromium compounds, in the presence of an acid.Particularly described is the oxidation of beta-picoline with sodium bichromate to obtain the sodium salt of nicotinic acid and 99.5% pure free acid, respectively.

Abstract: A method for decontaminating waste materials, wherein the residue of water leaching of the roasted chromium mineral containing water soluble hexavalent chromium compounds is wet ground and classified until obtaining such a granulometrical distribution that not more than 5-10% of the particles have an average size larger than 0.4 mm, and 40-60% of the particles have an average size less than 0.8 mm, and is then subjected to wet treatment under vigorous stirring at about 100.degree. C. with sulphur, in an aqueous emulsion of akaline or alkaline-earth sulphide for 1-4 hours, the percentage of solids in the reactor being in the range of 1-60%, preferably 30-35% by weight; and wherein the reacted slurry is thickened and filtered to provide the restored or decontaminated earth and an effluent, which is partly recycled to grinding or to reaction.