Abstract: Process of modification of a protide by fixation of an organic group to its molecule, comprising reacting the protide with a dithioic acid, salt or ester, the acid residue of which comprises the organic group to be fixed, while the remainder of the molecule has a leaving group structure, such that the dithioic compound reacts with the --NH.sub.2 or --NH-- of the protide molecule.

Abstract: Enzymes are fixed on carriers with a bis-dithioester capable of combining with the enzyme and with the carrier. The bis-dithioester has at each of its ends a group capable of reacting with an aimine function. The enzyme may be contacted with the bis-dithioester before the enzyme and carrier are combined. The carrier is an inorganic or organic solid.

Abstract: The froth flotation of a metal sulfide mineral is carried out using a thioamide as the collector in which the thioamide is of the formula ##STR1## R designating C.sub.5 to C.sub.17 alkyls, R' being H or (CH.sub.2).sub.n OR" and n an integer of 1 to 6, while Z is --OR" or ##STR2## where R" means H, CH.sub.3 or C.sub.2 H.sub.5.

Abstract: The present invention relates to a process for the preparation of beads of copolymers bearing reactive groups, by polymerization in suspension in a non-aqueous medium. According to the invention a free radical polymerization is effected of at least two unsaturated monomers, of which one is the carrier of a reactive group such as acid chloride, alkyl chloride, alkyl dithiobenzoate or carboxyalkyl, in a medium composed of two emulsified, immiscible organic liquids, to form beads of chemically reactive copolymers.

Abstract: Mono- and dithioic esters, the alcohol residue of which carries a group including one or more oxygen atoms, are prepared by the action of an oxygen-containing organic compound, carrying an active atom, upon a mixed magnesium salt of a mono- or dithioic acid, ##STR1## where Y is O or S, R is a hydrocarbon group and X is a halogen. The product obtained is treated with an aqueous acid. The new products so synthesized are of the type ##STR2## notably those where R' is a chain, --(CH.sub.2).sub.n --, with n=1 to 12, Z being --OH or --COOH and are used as a collector in the flotation of minerals.

Abstract: Process for the preparation of an organic dithio-acid by reaction of the corresponding dithio-ester and an alkali metal or alkaline earth metal hydrosulphide in a solvent in the presence of an excess of H.sub.2 S and treatment with a mineral acid. The dithioic acids so obtained can be utilized as collectors for the flotation of minerals.

Abstract: Process for the preparation of an organic dithio-acid by reaction of the corresponding dithio-ester and an alkali metal or alkaline earth metal hydrosulphide in a solvent in the presence of an excess of H.sub.2 S and treatment with a mineral acid. The dithioic acids so obtained can be utilized as collectors for the flotation of minerals.