Abstract: Hydrogenation catalysts based on palladium, platinum or rhodium comprising at least one other metal M which are deposited on zirconium oxide and silicon oxide supports. Process for the manufacture of these catalysts by successive impregnation of the support using palladium, platinum or rhodium and using another metal M. Use of these catalysts in hydrogenation reactions and in particular in preparing hydrogen peroxide.

Abstract: The present invention relates to a process for the pretreatment of activated carbon, capable of being employed especially for the purification of concentrated solutions of hydrochloric acid.

Abstract: The present invention relates to a process for the pretreatment of activated carbon, capable of being employed especially for the purification of concentrated solutions of hydrochloric acid.

Abstract: A process for extracting poly-beta-hydroxybutyrates from an aqueous suspension of microorganisms, in which an azeotropic distillation, and an extraction of the polymer by means of the solvent used, are carried out simultaneously.The poly-beta-hydroxybutyrates obtained can be used in medicine.

Abstract: Poly-.beta.-hydroxybutyrates obtained by biosynthesis are hydrolyzed in a reaction mixture containing poly-.beta.-hydroxybutyrates, water and an acid catalyst, in a solvent.

Abstract: A process for separating poly-.beta.-hydroxybutyrates from a biomass by extraction using at least one liquid halogenated solvent selected from the group consisting of chloroethanes and chloropropanes.

Abstract: Process for the manufacture of salts of hydroxycarboxylated polymers of reduced molecular weight, starting from the corresponding polymer salts of higher molecular weight, comprises reacting the polymer salt of higher molecular weight with an oxidizing agent in the presence of a solvent.

Abstract: Process for the manufacture of a salt of a poly-alpha-hydroxyacrylic acid, which salt contains monomeric units of the formula: ##STR1## in which R.sub.1 and R.sub.2 independently represent hydrogen or an alkyl group containing from 1 to 3 carbon atoms, and in which M represents the cationic radical resulting from the dissociation of a base, by reacting, with the base, in the presence of water, a solid polylactone derived from the corresponding poly-alpha-hydroxyacrylic acid, in which process the reaction is carried out in a liquid medium containing water and a diluent, the diluent being one which does not dissolve the polylactone and the salt produced and being present in an amount such that the polylactone and salt produced do not dissolve in the medium. In the process, an oxidizing agent is added to the liquid medium.

Abstract: Process for obtaining hydroxycarboxylic polymers of reduced molecular weight from corresponding polymers of higher molecular weight, comprising heating the polymer of higher molecular weight in a gaseous medium to a temperature of between 60.degree. and 240.degree. C.

Abstract: A solid composition for washing, cleaning and bleaching includes at least one basic compound and a solid polylactone derived from a polymer of an .alpha.-hydroxyacrylic acid. The .alpha.-hydroxyacrylic acid from which the solid polylactone is derived contains monomeric units of the formula ##STR1## wherein R.sub.1 and R.sub.2 independently represent hydrogen or an alkyl group containing 1 to 3 carbon atoms.

Abstract: A process is provided for the manufacture of salts of poly-alpha-hydroxyacrylic acids, which salts contain monomeric units of the formula ##EQU1## wherein R.sub.1 and R.sub.2 independently represent hydrogen or an alkyl group containing 1 to 3 carbon atoms and wherein M represents a cationic radical resulting from the dissociation of a base. A solid polylactone derived from the corresponding poly-alpha-hydroxyacrylic acid is reacted with the base in the presence of water and the reaction is carried out in a liquid medium containing a diluent so that the polyacetone and the salt produced do not dissolve in the medium.

Abstract: Process for the manufacture of polylactones derived from poly-.alpha.-hydroxyacrylic acids comprises heating a liquid aqueous solution of .alpha., .beta.-dichloropropionic acid to a temperature above 100.degree.C to convert the .alpha.,.beta.-dichloropropionic acid to the corresponding .alpha.-chloroacrylic acid and polymerizing the .alpha.-chloroacrylic acid in the aqueous solution in the presence of a polymerization catalyst to polymerize, hydrolyze and lactonize the .alpha.-chloroacrylic acid.The products obtained can be used as intermediates for the synthesis of salts of poly-.alpha.-hydroxyacrylic acids.