摘要:
Thermally-stable silicone elastomers are prepared from organopolysiloxane compositions by polyaddition, polycondensation or vulcanization reactions in the presence of peroxide; the thermal stability of the silicone elastomers is achieved by the inclusion of an additive derived from an iron (III) complex.
摘要:
Thermally-stable silicone elastomers are prepared from organopolysiloxane compositions by polyaddition, polycondensation or vulcanization reactions in the presence of peroxide; the thermal stability of the silicone elastomers is achieved by the inclusion of an additive derived from an iron (III) complex.
摘要:
The invention relates to a method for preparing carbene by means of deprotonation of a precursor salt using a strong base. A purpose of the invention is to enhance the synthesis of carbenes, i.e. to simplify same, to make said synthesis more economical and to obtain a liquid or solid, stable and pure form constituting a catalytic system that is easy to store and use and that has a higher efficiency, higher yield and higher selectivity than carbene catalysts of the prior art. In order to do so, the method comprises deprotonation in a solvent including an alcohol. The invention also relates to an alcohol-containing solution and carbene, and to a solid that can be obtained from the solution, e.g. by means of sublimation.
摘要:
The invention relates to a silicone composition comprising components bearing ≡SiH/≡SiOH groups, which can be polymerised/cross-linked by means of a dehydrogenative condensation reaction in the presence of a carbene-type catalyst in solution.
摘要:
Catalysts, which are free of tin, are described which are useful in the reaction between an isocyanate and an alcohol, which is a key step for preparing polyurethane polymers. The catalyst is a metal complex or salt of formula (1): [Zn(L1)l1(L2)l2(Y)x] (1) in which: l1≧1 and l2=0 or 1; with l1+l2=2, x=1 or 2, the symbol L1 represents a ligand which is a β-dicarbonylato anion or the enolate anion of a β-dicarbonyl compound or an acetylacetato anion derived from a β-ketoester, when l1=2, the symbols L1 are identical or different, the symbol L2 represents an anionic ligand which is different from L1, and the symbol Y represents a neutral ligand; where the metal complex or salt C of formula (1) is not zinc diacetylacetonate.
摘要:
The present invention relates to an organopolysiloxane composition that can be vulcanized at room temperature into an elastomer that is crosslinked by polycondensation and that does not contain alkyltin-based catalysts and also to novel organopolysiloxane polycondensation catalysts.
摘要:
The present invention relates to an organopolysiloxane composition that can be vulcanized at room temperature into an elastomer that is crosslinked by polycondensation and that does not contain alkyltin-based catalysts and also to novel organopolysiloxane polycondensation catalysts.
摘要:
The present invention relates to an organopolysiloxane composition that can be vulcanized at room temperature into an elastomer that is crosslinked by polycondensation and that does not contain alkyltin-based catalysts and also to novel organopolysiloxane polycondensation catalysts.
摘要:
Catalysts, which are free of tin, are described for the reaction between an isocyanate and an alcohol, which is a key step for preparing polyurethane polymers.
摘要:
The invention relates to a method for preparation of fluorinated aromatic compounds from the corresponding amines by replacement of the amino group with a fluorine atom. The method of preparation of a fluoroaromatic compound from an aromatic compound with at least one amino group on the aromatic ring is characterized by the reaction of said aromatic amine compound with a nitrosating agent in the presence of a source of boron trifluoride in an organic medium, and carrying out a thermal treatment of the reaction medium comprising the diazonium salt thus obtained to give the fluoroaromatic compound directly by decomposition of the diazonium salt without intermediate isolation thereof.