Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
  • C07F7/02—Silicon compounds
  • C07F7/08—Compounds having one or more C—Si linkages
  • C07F7/0834—Compounds having one or more O-Si linkage
  • C07F7/0836—Compounds with one or more Si-OH or Si-O-metal linkage
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
  • C07F7/02—Silicon compounds
  • C07F7/08—Compounds having one or more C—Si linkages
  • C07F7/0834—Compounds having one or more O-Si linkage

Definitions

• the present invention relates to a new process useful for silylating triflic acid and its derivatives.
• Trimethylsilyl triflate is a silylating agent widely used in organic synthesis, in particular because of its high reactivity. Consequently, it would be particularly advantageous to be able to have this silylation reagent at a moderate manufacturing cost.
• trimethylsilyl triflate is prepared by reacting tetramethylsilane with triflic acid. These two reagents are conventionally used in a purified form so as to prevent any possible secondary reaction with their impurities.
• tetramethylsilane having a purity level between 90 to 95% generally contains 3 to 4% of 2-methylbutane, 1 to 2% of dimethylchlorosilane and 2 to 3% of methyldichlorosilane.
• dimethylchlorosilane is considered to be particularly troublesome insofar as it is also capable of reacting with triflic acid.
• dimethylchlorosilane is capable of reacting with triflic acid according to the following reaction scheme:
• the objective of the present invention is to provide a new protocol making it possible in particular to lead to trimethylsilyl triflate with a comparable yield but above all for a significantly lower manufacturing cost.
• the present invention is based on the demonstration of a selectivity of reaction between triflic acid and tetramethyl siiane.
• the main object of the present invention is a process for silylation of a compound of general formula I
• X identical or different, represent a fluorine atom or a radical of formula C n F 2n +! with n being an integer at most equal to 5 and preferably 2;
• the symbol GEA represents an electron-withdrawing group the possible functions of which are inert under the reaction conditions, advantageously a fluorine atom or a perfluorinated residue of formula CnF ⁇ + i with n integer at most equal to 3, advantageously 2 and - m represents an integer equal to 1 or 2, characterized in that the silylating agent is a derivative
• silylating agent reacts with the compound of general formula I in the presence of at least one compound of general formula II
• the silylation reaction is carried out in the presence in addition of at least one compound of formula III
• Y represents a chlorine atom.
• tetraalkylsiiane is used in the form of a mixture with at least one compound of general formula II and, where appropriate, at least one compound of formula III.
• the tetraalkylsiiane constitutes approximately 85 to 95% by weight of the said mixture.
• the compound of general formula I to be silylated according to the claimed process corresponds to general formula I in which the total number of carbon of the group Rf is advantageously between 1 and 5 and preferably between 1 and 3.
• the claimed process is particularly useful for the silylation of triflic acid.
• the silylation reagent is preferably a tetraalkylsiiane derivative, the alkyl group of which is chosen so as to have a carbon number and / or a compatible steric conformation with its vaporization under the operating conditions adopted for the silylation reaction.
• this tetraalkylsiiane has C1 to C4 groups and more preferably is tetramethylsilane.
• the silylation reaction is preferably carried out in the presence of a slight excess of silylation reagent compared to the compound of general formula I to be silylated.
• the silylation reagent can thus be used in an excess of 10 mol%.
• the presence in excess of tetraalkylsiiane advantageously makes it possible to orient the reaction selectively towards the preparation of the expected trialkylsilyl triflate and therefore to oppose the manifestation of secondary reactions with respect to the compound of general formula I such as that mentioned above. above between triflic acid and dimethylchlorosilane. In the present case, it is however important to point out that this excess is not limiting in terms of the reaction.
• the two reagents are brought into contact at a temperature between about 0 and 5 °.
• the silylation is preferably also carried out under an inert atmosphere and more particularly under an argon sweep.
• a gradual addition of the tetraalkylsiiane to the compound of general formula I is placed under an inert atmosphere.
• This addition of tetraalkylsiiane is carried out over a sufficient time so as to obtain a regular flow and release of alkane.
• the reaction is considered complete when no gas evolution is observed.
• the temperature of the reaction medium is allowed to rise to ambient temperature before distilling said mixture to recover the expected silylated derivative.
• This distillation can be carried out at atmospheric pressure. However, for economic reasons, it is advantageous to carry it out under pressure scaled down. In this way, the respective boiling temperatures of the reactants are lowered to values between 35 and 60 ° C.
• the expected silylated derivative is recovered with a purity level greater than 99%.
• the process of the invention is very particularly advantageous for carrying out the silylation of triflic acid with tetramethylsilane in the presence in particular of at least dimethylchlorosilane.
• This silylation reaction can also be carried out in the presence in addition of methyldichlorosilane and trimethylchlorosilane.
• It may especially be a mixture of tetramethylsilane with dimethylchlorosilane and optionally methyldichlorosilane and / or trimethylchlorosilane.
• the tetramethylsilane represents 85 to 95% by weight of the mixture.
• the first step is the removal of the unreacted tetramethylsilane.
• the reaction medium can be brought to a temperature of the order of 50 ° C and under a pressure of between approximately 300 and 500 mbar.
• the trimethylsilyl triflate collected at the end of the protocol of the present invention advantageously has a purity greater than 99% and preferably of the order of 99.9%.
• the dimethylchlorosilane present as an impurity in the starting tetramethylsilane is also recovered during this distillation. This clearly confirms the selectivity of the silylation reaction.
• reaction medium is then left to rise to ambient temperature and the assembly is equipped with a distillation column with INOX packing.
• the reaction medium is brought to 50 ° C. under 300-500 mbar and 9.72 g of unreacted Me 4 Si are distilled.
• reaction medium After returning to ambient temperature, the reaction medium is distilled under a vacuum of 110 mbar and two fractions are collected which are identified in Table 1 below.
• the 36.78 g distillation pellet consists of 44% mol of CF 3 SO 3 H, 44% mol of CF 3 SO 3 SiMe 3 and 11% mol of MeHSiCI 2 .
• Rn so i é (CF 3 SO 3 SiMe 3 ) 63.5% (pure 99.9%)

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• Organic Chemistry (AREA)

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• 1998
  • 1998-02-27 FR FR9802437A patent/FR2775478B1/fr not_active Expired - Fee Related
• 1999
  • 1999-02-24 EP EP99904945A patent/EP1056753A1/fr not_active Withdrawn
  • 1999-02-24 WO PCT/FR1999/000415 patent/WO1999043687A1/fr not_active Application Discontinuation
  • 1999-02-24 CN CN99803250A patent/CN1291985A/zh active Pending
  • 1999-02-24 AU AU25265/99A patent/AU2526599A/en not_active Abandoned
  • 1999-02-24 JP JP2000533439A patent/JP2002504557A/ja active Pending
  • 1999-02-25 ZA ZA9901521A patent/ZA991521B/xx unknown

Non-Patent Citations (1)

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