Abstract: The production of SiOC-bonded, linear polydimethylsiloxane-polyoxyalkylene block copolymers comprising repeating (AB) units by reaction of polyether diols with trifluoromethanesulfonic acid-acidified, equilibrated ?,?-diacetoxypolydimethylsiloxanes is described, wherein the reaction is undertaken by adding a solid, liquid or gaseous base, optionally using inert solvents.

Abstract: A process for producing alkoxysiloxanes by thermal reaction of at least one waste silicone with at least one alkali metal alkoxide and at least one alcohol. The process includes a first step of reacting the at least one waste silicone by mixing with at least one alcohol and at least one alkali metal alkoxide with heating, but without removing any potentially occurring water from the reaction mixture, and a second step of neutralizing the reaction mixture resulting from this reaction using at least one Brønsted acid and separating the solid constituents, and subsequently isolating the alkoxysiloxane by thermal separation of volatile compounds.

Abstract: A process for producing one or more alkoxysiloxanes by thermal reaction of at least one siloxane parent structure with at least one alkali metal alkoxide and at least one alcohol, where the process includes mixing, while heating, the at least one siloxane parent structure with the at least includes one alcohol and the at least one alkali metal alkoxide to form a reaction mixture, neutralizing the reaction mixture by addition of at least one Brønsted acid and optionally with addition of at least one solvent, and subsequently isolating the one or more alkoxysiloxanes by thermal separation of volatile compounds. Potentially occurring water is not removed from the reaction mixture and the reaction mixture does not include solvents which form an azeotrope with water and/or further dehydrating agents.

Abstract: Processes may produce alkoxysiloxane(s) by reaction of siloxane parent structure(s) with alkali metal alkoxide(s). Such processes may include reacting siloxane parent structure(s) by mixing with alkali metal alkoxide(s) with heating and optionally adding silicon dioxide, but without adding alcohol and without removal of any potentially occurring water from the reaction mixture; and neutralizing the resulting reaction mixture by adding Brønsted acid(s), optionally solvent(s), and preferably separating solid constituents; and subsequently isolating the alkoxysiloxane(s) by thermally separating volatile compounds. The siloxane parent structure(s) may be a hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), mixture of cyclic branched D/T type siloxanes, silicone oils preferably including at least 100 D units, polydimethylsiloxanediol(s), and/or ?,?-divinylsiloxane(s).

Abstract: Process for producing SiOC-bonded, linear polydimethylsiloxane-polyoxyalkylene block copolymers comprising repeating (AB) units, comprising pretreating acidified, end-equilibrated ?,?-diacetoxypolydimethylsiloxanes with a base and reacting the ?,?-diacetoxypolydimethylsiloxanes resulting therefrom with polyether diols in the presence of a solid, liquid or gaseous base, optionally using inert solvents.

Abstract: The invention describes (i) reaction systems for the production of siloxanes bearing acetoxy functions, comprising a) silanes and/or siloxanes bearing alkoxy groups and/or b) silanes and/or siloxanes bearing acetoxy groups, c) silanes and/or siloxanes bearing hydroxy groups, d) optionally simple siloxane cycles and/or DT cycles, e) a reaction medium, comprising acetic anhydride, perfluoroalkanesulfonic acid and preferably acetic acid, (ii) a process for producing linear or branched siloxanes bearing acetoxy functions and also the use of same for producing polyethersiloxanes.

Abstract: Described is a process for producing SiOC-bonded polyether siloxanes branched in the siloxane portion from cyclic branched siloxanes of the D/T type, wherein said process comprises in a first step reacting the mixtures of cyclic branched siloxanes of the D/T type with acetic anhydride optionally in admixture with simple siloxane cycles under acid catalysis to afford acetoxy-bearing branched siloxanes, in a second step performing the equilibration of the acetoxy-modified branched siloxane with superacid, preferably with addition of acetic acid and in a third step reacting the superacid-treated acetoxysiloxane with polyetherols optionally in the presence of bases and optionally in the presence of an inert solvent.

Abstract: Upcycling process for producing acidic, end-equilibrated siloxanes bearing acetoxy groups and having chain lengths of greater than 3 silicon atoms from end-of-life silicones by thermal digestion in an acidic reaction medium comprising acetic anhydride, acetic acid and at least one further Brønsted acid having a pKa of <4, the digestion taking place in a reactor having a volume of at least 1 liter.

Abstract: Described is a process for producing SiOC-bonded polyether siloxanes branched in the siloxane portion from cyclic branched siloxanes of the D/T type, wherein said process comprises in a first step reacting the mixtures of cyclic branched siloxanes of the D/T type with acetic anhydride optionally in admixture with simple siloxane cycles under acid catalysis to afford acetoxy-bearing branched siloxanes, in a second step performing the equilibration of the acetoxy-modified branched siloxane with trifluoromethanesulfonic acid, preferably with addition of acetic acid, and in a third step reacting the trifluoromethanesulfonic acid-treated acetoxysiloxane with polyetherols optionally in the presence of bases and optionally in the presence of an inert solvent.

Abstract: Curable condensation compounds are obtainable by a reaction of non-end-equilibrated acetoxy group-bearing siloxanes with at least one alkoxy-functional polysiloxane, in the presence of a catalyst.

Abstract: The method for the physical reutilization of sheet-like siliconized structures comprises treating the sheet-like siliconized structure in a liquid digestion system comprising acetic anhydride and/or an acetoxysiloxane, and at least one Brønsted acid, optionally solvent, preferably with addition of acetic acid, and removing the desiliconized sheet-like structure from the liquid phase.

Abstract: A process can be used for increasing the molecular weight of low molecular weight ?,?-polysiloxanediols. The process involves heating the low molecular weight ?,?-polysiloxanediols in the presence of acetic anhydride at temperatures of 80° C. to 220° C., preferably at temperatures of 100 to 200° C., and particularly preferably at temperatures of 120-180° C., for 1 h to 24 h, preferably for 2 h to 16 h, and particularly preferably for 3 h to 12 h. The molar amount of the silanol groups used is greater than that of the acetic anhydride used.

Abstract: A process can be used for preparing silicone (meth)acrylates, according to which at least one acetoxysilicone is reacted with at least one hydroxyfunctional (meth)acrylic acid ester. The corresponding silicone (meth)acrylates are useful, and can be used in curable compositions.

Abstract: SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymers of formula (I) C—B-(AB)a—C1 are produced by reaction of end-equilibrated ?,?-diacetoxypolydimethylsiloxanes with a mixture including at least one polyether polyol, preferably a polyether diol, and at least one polyether monool or at least one monohydric alcohol.

Abstract: Process for producing endcapped, liquid siloxanes having chain lengths of greater than 3 silicon atoms from end-of-life silicones, especially from silicone elastomers and/or silicone rubbers, by acid-catalysed depolymerization thereof in a solvent-free reaction system comprising at least one compound providing end groups MR, at least one compound providing D units, and at least one Brønsted acid.

Abstract: Processes are described for purifying acidic, preferably superacidic, in particular trifluoromethanesulfonic acid-acidified, end-equilibrated acetoxysiloxanes, wherein the acidic, preferably superacidic, in particular trifluoromethanesulfonic acid-acidified, acetic anhydride-containing and optionally acetic acid-containing equilibrated, preferably end-equilibrated acetoxysiloxane, which is optionally dissolved in an inert solvent, is contacted with a base, the precipitate is filtered off thereafter and then the filtrate obtained is optionally purified by distillation.

Abstract: Reaction system for preparing acetoxy function-bearing siloxanes having chain lengths of more than 3 silicon atoms, comprising silanes and/or siloxanes bearing alkoxy groups, silanes and/or siloxanes bearing acetoxy groups, silanes and/or siloxanes bearing hydroxy groups and/or simple siloxane cycles and/or DT cycles, and also a reaction medium comprising acetic anhydride, Brønsted acid and acetic acid, wherein Brønsted acids having a pKa ??1.30 are used, and wherein the acetic acid is present in the reaction system in amounts of 0.4 to 15.0 percent by weight, based on the reaction system, wherein the molar ratio of Brønsted acid used to acetic acid is in a defined range, with the proviso that either the sole use of trifluoromethanesulfonic acid and also of trifluoromethanesulfonic acid and acetic acid is excluded, and/or that the Brønsted acid used at least in part has a pKa between ?1.3 and >?13.5.

Abstract: Equilibrated trifluoromethanesulfonic acid-acidified ?,?-diacetoxypolydimethylsiloxanes, processes for the production thereof and SiOC-bonded, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA and a process for the production thereof are described, wherein the production of SiOC-bonded, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA is effected by reacting trifluoromethanesulfonic acid-acidified acetoxysiloxane with polyetherols optionally in the presence of buffer mixtures and optionally an additional condensation catalyst and optionally in the presence of an inert solvent.

Abstract: Curable condensation compounds are useful, obtainable by the reaction of end-equilibrated acetoxy group-bearing siloxanes with at least one alkoxy-functional polysiloxane, in the presence of a catalyst.

Abstract: Equilibrated trifluoromethanesulfonic acid-acidified ?,?-diacetoxypolydimethylsiloxanes, processes for the production thereof and SiOC-bonded, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA and a process for the production thereof are described, wherein the production of SiOC-bonded, linear polydimethylsiloxane-polyoxyalkylene block copolymers of the structure type ABA is effected by reacting trifluoromethanesulfonic acid-acidified acetoxysiloxane with polyetherols optionally in the presence of bases and optionally in the presence of an inert solvent.