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.
摘要:
The invention concerns a method for the synthesis of chlorinated aniline on the ring and comprising at least a sp3 hybridization carbon atom both perhalogenated and bearing a fluorine atom. Said method is characterized in that it comprises a step which consists in chlorinating a precursor aniline of said chlorinated aniline, said chlorination being carried out in a hydrofluoric medium capable of exchanging chlorine and fluorine in benzyl position. The invention is useful for the synthesis of organofluorinated and/or chlorinated compounds.
摘要:
The invention relates to a reagent which is useful for the synthesis of oxysulphide-containing fluorine-containing organic derivatives by reacting with an oxide of sulphur, especially sulphur dioxide, characterized in that it comprises:a) a fluorocarboxylic acid of formula E.sub.w --CF.sub.2 --COOH where E.sub.w is an electron-withdrawing group or atom which is at least partially salified by an organic or inorganic cation, andb) an aprotic polar solvent; andin that the content of releasable protons carried by its various components, including their impurities, is at most equal to half the initial molar concentration of the said fluorocarboxylic acid.This reagent can be used by heating in order to form fluorine-containing sulphinic or sulphonic acids.