Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/06—Preparatory processes
• • 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
  • C07F7/0838—Compounds with one or more Si-O-Si sequences
  • C07F7/0872—Preparation and treatment thereof
  • C07F7/0876—Reactions involving the formation of bonds to a Si atom of a Si-O-Si sequence other than a bond of the Si-O-Si linkage

Definitions

• This invention relates to a process for the production of low molecular weight silanol- stopped materials by reacting hexaorganocyclotrisiloxanes with water in the presence of catalytic amounts of a strong base.
• the reaction is preferably run in a water/acetone system.
• silanol stopped oligomeric siloxane materials are made by two processes.
• the first process involves controlled hydrolysis of dichlorodimethylsilane in a water/polar solvent mixture in the presence of a neutralizing agent, such as sodium bicarbonate or ammonia. This process produces a significant amount of waste and about 30% of cyclic oligomers which have to be removed from the final product by vacuum stripping.
• the second process involves ring opening polymerization of hexamethylcyclotrisiloxane in a water/organic solvent mixture in the presence of acid- activated clay, (such as FILTROL-20) as disclosed in US Patent 3,853,932, or the acidic or basic ion exchange resins as described in for instance, US Patent 3,309,390.
• acid- activated clay such as FILTROL-20
• the process requires filtration of the catalyst and high vacuum distillation to remove cyclic oligomers formed during the ring opening polymerization.
• the present invention provides for a process for the production of linear silanol stopped siloxanes comprising: conducting a ring opening polymerization of a hexaorganocyclotrisiloxane having the formula:
• R and R are independently selected from the group of one to forty carbon atom monovalent radicals, in a solvent comprising a mixture of water and a volatile polar, aprotic organic solvent in the presence of catalytic amounts of a strong base;
• washing with water to remove salts or, alternatively, stripping water and acetone from the batch and filtering the neutral salts.
• Optional or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not. It has been discovered that a ring opening polymerization of hexamethylcyclotrisiloxane, D 3 , in water/volatile polar, aprotic organic solvent mixture in the presence of catalytic amounts of a strong base such as LiOH, NaOH, KOH, or a mixture thereof proceeds with a high rate to afford linear oligomeric silanol-stopped siloxanes with a high yield, typically above about 90%.
• the volatile polar organic solvent used with water to form the solvent of the process must be miscible with water.
• Non-limiting examples of such volatile polar aprotic organic solvents are low molecular weight ketones, e.g. acetone.
• the amount of cyclic oligomer by-product, such as octamethyl-cyclotetrasiloxane, D4, is very low.
• D 3 also referred to as hexaorganocyclotrisiloxane, is defined as follows:
• R 1 and R 2 are independently selected from the group of one to forty carbon atom monovalent radicals where such radicals may or may not be substituted by other substituents, e.g. halogen atoms.
• substituents e.g. halogen atoms.
• this definition specifically includes, without limitation, fluoro substituted radicals such as 3,3,3-trfluoropropyl as well as perhalo-alkyl radicals and perhalo-aryl radicals.
• the catalyst With respect to neutralization, the catalyst must be neutralized to prevent condensation of the silanols during removal of solvents. It is preferable to be close to a pH 7 after neutralization of the basic catalyst preferably the pH range after neutralization is from about 6.7 to about 7.3, more preferably from about 6.5 to about 7.5 and most preferably from about 6.0 to about 8.0. This may be accomplished by measuring the base content of the reaction and precisely measuring any acid, including hydrochloric, sulfuric, acetic, etc. However, such an approach requires strict control of the concentration of acids, because if any slight excess or absence of such acids from exact stoichiometry would result in a pH which is too high or too low and cause loss of silanol during stripping.
• Useful deactivating agents include carbon dioxide, and acidic salts of polybasic acids. Under some conditions even carbon dioxide can produce deactivated salts which are too high in pH.
• polybasic acids are acids containing more than one neutralizable acid functionality per molecule, which when partially neutralized function as a buffering agent for control of pH. Therefore, most preferred are salts whose aqueous solution are close to pH 7 and which will react with the basic catalyst to produce deactivation salts which are also in the range of pH 6 to pH 8.
• Preferred are the monobasic salts of di- or tri-basic acids (a subset of polybasic acids). Such salts would include the partially neutralized alkali metal salts of such polybasic acids, e.g.
• sodium or potassium hydrogen sulfate mono sodium or potassium oxalate and other dibasic organic acids, e.g. mono sodium or potassium dihydrogenphosphate. Most preferred is the mono sodium or potassium dihydrogenphosphate.
• alkali metal includes lithium, sodium, potassium, rubidium and cesium.
• the process of the present invention produces linear siloxanes in excess of 90% yield and preferably in excess of 93% yield, more preferably in excess of 95% yield and most preferably in excess of 97% yield.
• the process of the present invention allows the production of linear silanol-stopped oligomers with a higher yield than known processes.
• the process of the present invention provides a faster rate of reaction, and the filtration step required in the prior art is eliminated by the use of a homogenous catalyst system.
• the process of the present invention produces less cyclic byproduct than the prior art, thereby eliminating the need for a high vacuum distillation.
• the silanol content was determined by placing a thin layer of the sample in a cup, evaporating the residual acetone, then performing an FTIR.
• the D3 + D4 content after four hours of reaction was determined to be 5.67% and the silanol content to be 7.14%.
• the D3 +D4 content after six hours of reaction was determined to be 5.66% and the silanol content to be about 6.95%.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Silicon Polymers (AREA)
• Macromonomer-Based Addition Polymer (AREA)

Priority Applications (4)

Applications Claiming Priority (4)

Publications (2)

Family

ID=26733955

Family Applications (1)

Country Status (9)

Families Citing this family (5)

Citations (8)

Family Cites Families (5)

• 2002
  • 2002-01-23 DE DE60224362T patent/DE60224362T2/de not_active Expired - Fee Related
  • 2002-01-23 WO PCT/US2002/022501 patent/WO2002092607A1/en not_active Ceased
  • 2002-01-23 ES ES02756491T patent/ES2296980T3/es not_active Expired - Lifetime
  • 2002-01-23 KR KR10-2003-7009716A patent/KR20030094237A/ko not_active Abandoned
  • 2002-01-23 EP EP02756491A patent/EP1358191B1/en not_active Expired - Lifetime
  • 2002-01-23 US US10/055,199 patent/US6433204B1/en not_active Expired - Fee Related
  • 2002-01-23 AT AT02756491T patent/ATE382625T1/de not_active IP Right Cessation
  • 2002-01-23 CN CNB028040090A patent/CN100408585C/zh not_active Expired - Fee Related
  • 2002-01-23 JP JP2002589490A patent/JP4147115B2/ja not_active Expired - Fee Related

Patent Citations (8)

Non-Patent Citations (3)

Also Published As

Similar Documents

Legal Events