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
  • C07F7/12—Organo silicon halides
  • C07F7/14—Preparation thereof from optionally substituted halogenated silanes and hydrocarbons hydrosilylation reactions

Definitions

• the present invention relates to a process for preparing a ⁇ -haloalkyl dialkylhalosilane.
• the present invention relates in particular to a process for the preparation of 3-chloropropyl dimethylchlorosilane, by hydrosilylation of dimethylhydrogencochloron silane with allyl chloride and a catalyst based on a metal of the platinum group and recovery of said metal.
• the quantities of metal of the platinum mine involved are often high in order to obtain a satisfactory yield.
• This amount of metal catalyst is generally greater than 30 p. p. m. calculated with respect to the total weight of the reaction mixture.
• HaI represents a halogen atom chosen from among the chlorine, bromine and iodine atoms, the chlorine atom being preferred,
• R 2 and R 3 which are identical or different, each represent a monovalent hydrocarbon group chosen from a linear or branched alkyl radical having from 1 to 6 carbon atoms and a phenyl radical, and
• s represents an integer between 2 and 10 inclusive, in which process, at the end of the hydrogenosilylation reaction, the reaction medium is distilled to separate the product of formula (I), this distillation resulting in a liquid pellet comprising a little of the product formed of formula (I) not separated by distillation, by-products and the catalytic mineral implemented.
• the recovery of the catalytic metal can be carried out on the liquid distillation pellet by carrying out the following steps:
• one of the essential objectives of the present invention is to provide a process for the preparation of a ⁇ -haloalkyl dialkylhalosilane of the type described above in which the reaction kinetics of hydrolysis is perfectly under control. to be able to minimize the amount of H-Hal formed in the aqueous hydrolysis phase.
• Another essential objective of the present invention is to propose a process for preparing a ⁇ -haloalkyl dialkylhalosilane in which the The procedure for recovering the catalytic metal is simplified by no longer using the adsorption step of the catalytic metal on an adsorbent solid.
• Another essential objective of the present invention is to propose a process for preparing a ⁇ -haloalkyl dialkylhalosilane which makes it possible to lead to a pellet which can be easily handled and which has a low level of hydrolyzable halide Si-HaI ⁇ 2%, expressed by weight of Hal.
• Still another object of the present invention is to provide a process for the preparation of a ⁇ -haloalkyl dialkylhalosilane wherein the recovery of the catalytic metal is from the distillation pellet using conventional catalyst manufacturer techniques, but without doing so.
• HaI represents a halogen atom chosen from among the chlorine, bromine and iodine atoms, the chlorine atom being preferred,
• R 2 and R 3 which are identical or different, each represent a monovalent hydrocarbon group chosen from a linear or branched alkyl radical having from 1 to 6 carbon atoms and a phenyl radical, and - s represents an integer between 2 and 10 inclusive, said process comprising, at the end of the hydrogenosilylation reaction, an operation of distillation of the reaction medium to separate the formed product of formula (I), this distillation leading to a pellet; liquid comprising a little of the product formed of formula (I) not separated by distillation, by-products and the catalytic mineral implemented, and then an operation for recovering the catalytic metal from said pellet, said method being characterized in that, in order to recover the catalytic metal, there is proceeded to: • a controlled hydrolysis of the pellet resulting from the distillation of the reaction medium comprising the catalytic metal of the platinum group, said metal being in its original form of catalyst or in a transformed form this controlled hydrolysis being carried out according to a particular mode of operation which allows: a) the
• the metal of the platinum group is selected from platinum, iridium, palladium, rhodium, ruthenium and osmium, the preferred metal being iridium.
• suitable Ir-based catalysts are in particular:
• Ir-based catalysts are taken from the group of iridium complexes of the formula:
• R 4 represents an unsaturated hydrocarbon ligand comprising at least one carbon-carbon double bond and / or at least one triple bond
• these unsaturated bonds may be conjugated or non-conjugated, said ligand: being linear or cyclic (mono or polycyclic), having from 4 to 30 carbon atoms, having from 1 to 8 ethylenic and / or acetylenic unsaturations and optionally comprising one or more heteroatoms such as for example an oxygen atom and / or a silicon atom;
• iridium complexes of formula (IV) which are more suitable are those in the formula of which: the symbol R 4 is chosen from 1,3-butadiene, 1,3-hexadiene, 1,3-cyclohexadiene, 1,3-cyclooctadiene, 1,5-cyclooctadiene and 1,5-cyclododecatrien; 9 and norbornadiene, and the following compounds of formula:
• iridium complexes which are even more suitable, mention may be made of the following catalysts: di- ⁇ -chlorobis (divinyltetramethyldisiloxane) diiridium, di- ⁇ -chlorobis ( ⁇ -1,5-hexadiene) diiridium, di ⁇ -bromobis ( ⁇ -1,5-hexadiene) diiridium, di- ⁇ -iodobis ( ⁇ -1,5-hexadiene) diiridium, di- ⁇ -chlorobis ( ⁇ -1,5-cyclooctadiene) diiridium, di- ⁇ -bromobis ( ⁇ -1,5-cyclooctadiene) diiridium, di- ⁇ -iodobis ( ⁇ -1,5-cyclooctadiene) diiridium, di- ⁇ -chlorobis ( ⁇ -2,5-norbornadiene) diiridium, di- ⁇ -bromobis ( ⁇ -2,5-
• At least one hydrosilylation reaction promoter can be used in addition to the platinum-metal-based catalyst.
• the optional promoter (s), when one (or more) is used, is (are) introduced (s) generally at the beginning of the reaction, in the state in which they are located. (nt) normally, either in the form of a premix based on: promoter (s) + catalyst (s); or promoter (s) + all or part of the diorganohalosilane of formula (II); or promoter (s) + all or part of the alkene halide of formula (III).
• the catalyst can be used, and this is another preferred arrangement, in a homogeneous liquid medium, as described in JP-B-2,938,731 and EP-A-1 156 052.
• the reaction can be driving either continuously, either semi-continuously or discontinuously.
• recovery of the formed product of formula (I) and the catalytic metal of the platinum mine is carried out as indicated above.
• the amount of alkene halide of formula (III) used is preferably 1 to 2 moles per 1 mole of silane of formula (II).
• the amount of catalyst (s) (i) expressed in weight of metal of the platinum mine, it is in the range of 1 to 10,000 p. p. m, preferably from 10 to 2000 p. p. m. and more preferably ranging from 20 to 1000 p. p. m. based on the weight of silane of formula (II).
• the liquid distillation pellet is thus brought into contact with a quantity of water sufficient to transform all or at least the major part of the Si-HaI functions into Si-OH silanol functions and siloxane Si-O-chain linkages. Yes.
• the distillation pellet generally comprises a certain proportion of the halosilane of formula (I) not separated by distillation and the corresponding disilane, which leads to total halogen contents of the order of 40 to 50% by weight and halogen. ionic of the order of 15 to 25% by weight.
• total halogen means all the halogen atoms present in the pellet; the term “ionic halogen” is understood to mean all the so-called hydrolyzable halogens, that is to say essentially the Si-HaI functions which can react with water to form the corresponding halogen acid.
• the quantity of water used is strongly linked firstly to the degassing capacity of the halogen acid, which is a function of the water accumulated in the medium over time, and secondly to the operating parameters such as for example the stirring speed of the hydrolysis reactor, the temperature and / or the presence or absence of an inert gas acting as vector of the halogen acid ("stripping" system).
• the degassing of the halogenated acid formed is favored by "stripping" with a gas that is inert with respect to the hydrogen halide H-HaI formed and the products composing the pellet; in this case, it is recommended to use nitrogen or argon and to avoid water vapor or alcohol that react with halosilanes.
• the controlled hydrolysis may be carried out at atmospheric pressure or under reduced pressure, and optionally in the presence of an inert gas as explained above.
• the amount of water used is in the range of 1 to 5 moles and preferably 1 to 3 moles, per 1 mole of hydrolyzable halogen (Si-HaI function).
• the water is added to the distillation pellet at a rate that is adjusted to prevent any accumulation of water in the medium and thus the solubilization of the H-HaI acid formed at each instant.
• the precise value of this flow rate will depend on the geometrical characteristics of the hydrolysis reactor and also on the "stripping" conditions (nature of the inert gas, flow of the inert gas, hydrolysis temperature, agitation speed of the reactor) in the case where this operating system is used. The skilled person can easily determine, with simple tests, the precise value of the flow rate to be implemented for each operation.
• the water is added to the distillation residue at a rate which is in the range of 0.001 to 0.04 moles of water and preferably from 0.002 to 0.015 moles of water per minute and per mole of hydrolyzable halogen.
• the halogenated acid formed is then partially or completely solubilized in the medium and an ionic halogen content greater than 15% by weight is therefore preserved.
• Such a process leads to the formation of an aqueous phase and an organic phase with an equimassic distribution of the metal catalyst between these two phases; this way certainly makes it possible to achieve the objective of inerter the reactive pellet, but it leads over time to the formation of a sludge that is diffrimentally manipulable, incompatible with a reliable and reproductive process; moreover, this way raises the problem of the qualitative and quantitative analyzes of the catalytic metal.
• the hydrolysis arranged can be done at temperatures ranging from 0 ° C. to 100 ° C. at atmospheric pressure. Since the reaction is exothermic, it is preferred to carry out the casting of the water at moderate temperatures ranging from 10 to 80 ° C. A temperature control may be necessary.
• the medium obtained is monophasic and consists of an organic phase comprising the catalytic metal to be recovered.
• the product of formula (I) is 3-chloropropyl dimethylchlorosilane
• the product of formula (II) is dimethylhydrochlorosilane
• the product of formula (III) is allyl chloride.
• the hydrogen halide formed H-HaI is HCl.
• the temperature conditions are maintained throughout the test.
• the hydrochloric acid released in the form of gas is trapped in a slagging column where circulates a soda stream diluted to 30% by weight in water.
• the final medium is recovered and the ionic chlorine is analyzed: the final content is 0.13% by weight.
• Example 2 Gentle hydrolysis of the pellet to go below the limiting content of 2% by weight of ionic chlorine:
• 160 g of water are then introduced at a rate of 5 g / min or 0.06 mole of water per minute and per mole of hydrolyzable chlorine.
• the temperature conditions are maintained for 1 hour.
• the final medium is recovered and the ionic chlorine is analyzed: the final content is 4.30% by weight.
• the molar ratio water / chlorine hydrolyzable is 1, 97.

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• Chemical & Material Sciences (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2004
  • 2004-06-16 FR FR0406502A patent/FR2871802B1/fr not_active Expired - Fee Related
• 2005
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