Abstract: The invention relates to the field of silicon resins, particularly polymethylvinylsiloxane resins. The invention more specifically relates to a method for the production of polymethylvinylsiloxane resins comprising at least two different types of siloxy motifs R3SiO1/2 (motif M) and SiO4/2 (motif Q, optionally QOH), said method comprising the following steps: a) producing a siloxane resin comprising motifs Q by acidic hydrolysis of a siloxane resin precursor, preferably an alkaline silicate; b) functionalizing the siloxane resin obtained in step a) with halogenosilanes in the presence of an apolar solvent, the functionalizing generating sub-products including volatile oligosiloxanes (silox); c) recovering silox produced in step b) in a solution in the apolar solvent; and d) subjecting the resin functionalized in step b) to rearrangement with the aid of a strong base in order to eliminate the silanols, wherein at least a part of the silox produced during step b) and recovered in step c) is recycled.

Abstract: The invention relates to the field of silicon resins, particularly polymethylvinylsiloxane resins. The invention more specifically relates to a method for the production of polymethylvinylsiloxane resins comprising at least two different types of siloxy motifs R3SiO1/2 (motif M) and SiO4/2 (motif Q, optionally QOH), said method comprising the following steps: a) producing a siloxane resin comprising motifs Q by acidic hydrolysis of a siloxane resin precursor, preferably an alkaline silicate; b) functionalizing the siloxane resin obtained in step a) with halogenosilanes in the presence of an apolar solvent, the functionalizing generating sub-products including volatile oligosiloxanes (silox); c) recovering silox produced in step b) in a solution in the apolar solvent; and d) subjecting the resin functionalized in step b) to rearrangement with the aid of a strong base in order to eliminate the silanols, wherein at least a part of the silox produced during step b) and recovered in step c) is recycled.

Abstract: A method has been developed for making regenerated cellulose yarn. The method includes the steps of spinning a solution derived from cellulose or a cellulose derivative in a molten state through at least one extrusion die, then regenerating the cellulose by treating the resulting yarn, wherein a silylated cellulose derivative is prepared by reaction with a silylating agent; the silylated cellulose is extracted from the synthesis reaction medium; then spun through at least an extrusion die; and the resultant yarn treated with a desilylation agent to regenerate the cellulose and a siloxane. The resulting cellulose yarns or fibers may be used for making woven or knitted textile surfaces or non-woven surfaces. Said yarns or fibers are also useful as reinforcing fibers in elastomeric materials and more particularly, in tires.

Abstract: The present invention relates to a process for the manufacture of cyclic polydiorganosiloxanes, especially octamethylcyclotetrasiloxane (D.sub.4) and decamethylcyclopentasiloxane (D.sub.5) by depolymerization of polydiorganosiloxanes in the presence of an initiator, characterized in that the initiator comprises either:1) at least one hydroxide chosen especially from the group made up of caesium, rubidium or quaternary phosphonium hydroxides, or:2) the association of a fluorine-free caesium or rubidium salt, or of a salt of quaternary phosphoniums, with a hydroxyl-containing strong base of an alkali or alkaline-earth metal other than Cs and Rb.

Abstract: Mono-, di- and triphenols are selectively monomethylated by reaction with para-dimethoxybenzene in the presence of a catalytically effective amount of an acid catalyst.

Abstract: The bis-(N-carboalkoxyanilino)methanes, optionally in the presence of at least one alkyl N-phenylcarbamate, are selectively rearranged into methylenedi(phenylurethane), MDU, in the presence of an effective amount of hydrofluoric acid.

Abstract: Methylenedi(phenylurethane), MDU, is selectively prepared by condensing an alkyl N-phenylcarbamate with a methylenating agent, e.g., formaldehyde or a precursor thereof, in the presence of a catalytically effective amount of the protonic acid, hydrofluoric acid.

Abstract: Methylhydroquinone (MeHQ) or methyl ether derivative thereof is prepared by contacting paramethoxyphenol or para-dimethoxybenzene with an acid catalyst, preferably a solid acid catalyst, at a temperature ranging from 100.degree. to 300.degree. C.