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
  • C07F7/121—Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20
  • C07F7/125—Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20 by reactions involving both Si-C and Si-halogen linkages, the Si-C and Si-halogen linkages can be to the same or to different Si atoms, e.g. redistribution reactions

Definitions

• the present invention relates to a process for the production of trimethylchlorosilane (M3) and methyltrichlorosilane (M1) by means of disproportionation of dimethyldichlorosilane (M2) in the presence of an Al 2 O 3 catalyst, the dimethyldichlorosilane being used in the form of a silane mixture containing 80-100 wt .-% contains dimethyldichlorosilane (M2), and the difference in proportion to 100% by weight contains M1 and M3.
• Trimethylchlorosilane (M3) is an industrially important raw material; it is used, for example, in the manufacture of silicones, for hydrophobization and in organic synthesis.
• M3 the technically available amount of M3 is limited. It arises, for example, as a by-product in the Müller-Rochow process, or it can be obtained from tetramethylsilane (TMS) - also a by-product of the Müller-Rochow process.
• TMS tetramethylsilane
• the silane mixture produced in the Müller-Rochow process contains the main product dimethyldichlorosilane (M2) in concentrations of 70% by weight to 90% by weight, but also methyltrichlorosilane (M1), trimethylchlorosilane (M3), dimethyltetrachlorodisilane and other silanes. These must be separated from one another by rectification.
• EP0219718A1 discloses the disproportionation of M2 to M3 and Ml with a catalyst complex of AlX 3 and CuX n , where X is a halogen atom and n is 1 or 2. Specifically, several experiments are carried out in Examples 2 and 3 in which (CH 3 ) 2 SiCl 2 in the presence of CUCI / AICI 3 for 5 hours at temperatures in the range of 264-300 ° C. in an autoclave at pressures between 34.5-37.95 bar is implemented. Both the molar ratio CuCl / AlCl 3 and the temperature are varied.
• Example 3 a maximum of 8.19 wt .-% are obtained at M3, once at a temperature of 323 ° C, 5.05 wt .-% of AlCl 3 and a molar ratio of CuCI / AICI 3 of 0.26 and another time at a temperature of 322 ° C., 5.05% by weight of AICI3 and a molar ratio of CUCI / AICI3 of 0.5.
• 17.03% by weight or 17.99% by weight of M1 are also produced.
• the M3 content of 8.19% by weight should correspond to 85% of the possible thermodynamic equilibrium in relation to M3.
• a fundamentally negative point about the disclosed process is that a continuous process would not be possible since AICI 3 would sublime at approx. 180 ° C. and thus be discharged from the reactor.
• the overstoichiometric proportion of Ml in the product mixture also indicates that decomposition of methylchlorosilane must have occurred, i.e. unfavorable side reactions are taking place.
• the process described is therefore not suitable for producing M3 in technically relevant quantities.
• No. 3,384,652 discloses disproportionation reactions of organo (chloro) silanes in the presence of crystalline aluminosilicate catalysts (zeolites).
• zeolites crystalline aluminosilicate catalysts
• M2 dimethyldichlorosilane
• M3 trimethylchlorosilane
• Ml methyltrichlorosilane
• the product mixture also contains 40% M2 that has not reacted.
• the amounts of M3 and Ml obtained and the formation of SiCl 4 and TMS contradict the thermodynamics of the disproportionation reaction.
• processes for enriching trimethylchlorosilane (M3) in low-boiling silane mixtures are known in the literature.
• the high M3 yields in both examples are due to the high TMS content in the starting mixture.
• US5493043 discloses a process for enriching a low-boiling methylsilane mixture in dimethylhydrochlorosilane or trimethylchlorosilane (M3) in the presence of an aluminum oxide catalyst above 150.degree.
• the methylsilane mixture comes from the distillate of the Müller-Rochow synthesis.
• at least tetramethylsilane (TMS) and dimethyldichlorosilane (M2) should be included in the mixture and the temperature of the process should be in the range of 180-304 ° C.
• No. 3,207,699 discloses catalysts impregnated with trimethylsilyl groups for the rearrangement of trimethylsilane.
• Example VI an ⁇ -Al 2 O 3 catalyst is moistened and impregnated with trimethylsilane at 510.degree.
• US Pat. No. 3,346,349 discloses synthetic silica-alumina catalysts which have been activated with organosilanes or halosilanes of the formula R 1 R n SiX (3-n) , where R n and Ri are hydrogen or a C1-C5-alkyl group, where X is halogen and n is an integer from 0-3.
• the catalysts are used to produce dimethyldichlorosilane from methylated chlorosilanes.
• the process according to the invention gives very good M3 yields which are close to the thermodynamic maximum.
• Ml is formed in stoichiometric amounts, which indicates that no side reactions or decomposition reactions take place.
• the subject of the present invention is a process for the production of trimethylchlorosilane by means of disproportionation of dimethyldichlorosilane (M2) in the presence of an Al 2 O 3 - catalyst, whereby the dimethyldichlorosilane is used in the form of a silane mixture, which at least 80 wt .-% dimethyldichlorosilane (M2) contains, and wherein the difference proportion to 100 wt .-% contains M1 and M3.
• dismutation - means that a single silane rearranges to form two or more different silanes (e.g. M2 -> M3 + M1), whereby the substituents of the silanes formed (e.g. Cl and CH 3 ) are one have a different substitution pattern from the original silane.
• a silane disproportionation - strictly speaking, it should be called dismutation - means that a single silane rearranges to form two or more different silanes (e.g. M2 -> M3 + M1), whereby the substituents of the silanes formed (e.g. Cl and CH 3 ) are one have a
• Disproportionation reaction can be illustrated, for example, by the following formula (I):
• M2 is used in the form of a silane mixture which
• M2 dimethyldichlorosilane
• the silane mixture preferably contains 98-100% by weight M2, very particularly preferably the silane mixture contains 99.5-100% by weight M2.
• the difference portion preferably contains exclusively Ml.
• the AI 2 O 3 catalyst is preferably activated before the disproportionation by
• radicals R in formula (II) are preferably selected independently of one another from a methyl radical or hydrogen.
• Examples of chlorosilanes of the formula (II) are Me 2 SiCl 2 ,
• the Al 2 O 3 catalyst is particularly preferably activated before the disproportionation by passing HCl gas over the catalyst.
• the contact time during activation is usually 1-100 seconds.
• An Al 2 O 3 catalyst having a BET surface area in the range of 100 is preferred - 200 m 2 / g used, particularly preferably in the range of 150 -180 m 2 / g.
• BET surface area is the specific surface area that is determined by the adsorption of nitrogen in accordance with the ASTM D 3663-78 standard, which is based on the Brunnauer-Emmet-Teller method (J.Am.Chem.Soc . 1938, 60, 309-319).
• the pore volume can be determined e.g. via mercury porosimetry.
• the Al 2 O 3 catalyst can contain up to 20% by weight of other elements, for example carbon, or smaller amounts of silicon and / or chlorine. For example, it may contain residues from auxiliary materials that were used for shaping.
• the Al 2 O 3 catalyst is usually in the form of a shaped body.
• Shaped bodies are, for example, tablets, granules, spheres, rings, cylinders, hollow cylinders.
• the shaped bodies preferably have a size in the range from 1-10 mm, particularly preferably in the range from 2-4 mm.
• a ⁇ -Al 2 O 3 catalyst is particularly preferably used.
• a ⁇ -Al 2 O 3 catalyst is very particularly preferred as a shaped body with a BET surface area in the range from 100-200 m 2 / g, a pore volume in the range from 0.1-1 cm 3 / g and a size in the range from 1 - 10 mm are used.
• the process according to the invention is particularly preferably carried out at a temperature in the range from 390 ° C. to 490 ° C. and a pressure less than 1 bar.
• the process can be carried out continuously or batchwise, with continuous being preferred. If the process is carried out continuously, M2 can be separated off from the product mixture by distillation and reintroduced into the process.
• the contact time for the silane mixture is usually in a range of 0.1-120 seconds, preferably in a range of 1-30 seconds, particularly preferably the contact time is in a range of 10-15 seconds.
• the trimethylchlorosilane After completion of the reaction, the trimethylchlorosilane can be separated from the reaction mixture by, for example, distillation.
• the experiments were carried out in a tubular reactor filled with Al 2 O 3 (Al 3438 T 1/8 ", Pellets, BASF).
• the reactor was heated with a heating jacket, and the heating zone filled with catalyst had a height of approx Diameter of 5 cm.
• the M2 was first vaporized and preheated before it could come into contact with the catalyst.
• the product mixture was condensed with a reflux condenser and collected.
• GC measurements were carried out with an Agilent 6890N (TCD detector; columns: HP5 from Agilent: length: 30 m / diameter: 0.32 mm / film thickness: 0.25 ⁇ m; RTX-200 from Restek: length: 60 m / diameter : 0.32 mm / film thickness: 1 mih). Retention times were compared with the commercially available substances, all chemicals were used as purchased. All data are in percent by weight.
• the catalyst was activated with evaporated SiCl 4 at 450 ° C. (internal measurement in the middle of the bed). At an internal reactor temperature of 378 ° C., 150 mL of evaporated M2 were pumped through the catalyst bed with a contact time in the reactor of ⁇ 20 s, and the condensed product mixture was analyzed.
• the product mixture consisted of 74.1% by weight of M2, zu
• the product mixture consisted of 75.1% by weight of M2, zu
• the catalyst was activated with HCl gas at 450 ° C. (internal measurement in the middle of the bed).
• the catalyst was activated with a mixture of HCl gas and evaporated SiCl 4 at 450 ° C. (internal measurement in the middle of the bed).
• a mixture of HCl gas and evaporated SiCl 4 at 450 ° C. (internal measurement in the middle of the bed).
• 150 mL of evaporated M2 were pumped through the catalyst bed with a contact time in the reactor of ⁇ 18 s, and the condensed product mixture was analyzed.
• the product mixture consisted of 68.3% by weight of M2, 14.4% by weight of M1 and 7.7% by weight of M3. In addition, 8.4% by weight of partially chlorinated methylated disiloxanes were still present, which cannot be used any further.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Catalysts (AREA)

Priority Applications (6)

Applications Claiming Priority (1)

Publications (1)

Family

ID=68808361

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (2)

Citations (6)

Family Cites Families (3)

• 2019
  • 2019-12-04 KR KR1020227012642A patent/KR102807398B1/ko active Active
  • 2019-12-04 JP JP2021563637A patent/JP7314309B2/ja active Active
  • 2019-12-04 CN CN201980093492.4A patent/CN113508119B/zh active Active
  • 2019-12-04 WO PCT/EP2019/083663 patent/WO2021110256A1/de not_active Ceased
  • 2019-12-04 EP EP19816636.5A patent/EP4069705B1/de active Active
  • 2019-12-04 US US17/780,559 patent/US12291544B2/en active Active

Patent Citations (6)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events