Preparation of 3,3'-oxybis(1,1,1,3,5,5,5-heptamethyltrisiloxane)

Abstract

A method for preparing 3,3'-oxybis(1,1,1,3,5,5,5-heptamethyltrisiloxane) is provided. The 3,3'-oxybis(1,1,1,3,5,5,5-heptamethyltrisiloxane) is useful in foam formulations, such as polyisocyanurate and polyurethane foams.

Description

PREPARATION OF 3,3'-OXYBlS(l,1.1.3,5,5,5-HEPTAMETHYLTRISlLOXANE)CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No.63 / 745,546 filed on January 15, 2025 under 35 U.S.C. §119 (e). U.S. Provisional Patent Application Serial No. 63 / 745,546 is hereby incorporated by reference.FIELD

[0002] This invention relates to a new method for preparation of 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane). The 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane) has high yield and high purity.INTRODUCTION

[0003] Decamethylcyclopentasiloxane (D5) has been used as a nucleator for polyurethane foams. However, there is an industry need to replace D5 and other cyclic siloxanes (e.g., D4, D6, and others) due to European Union REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals) and other regulations. Short chain linear polydimethylsiloxanes have the potential to replace D5, however, short chain linear polydimethylsiloxanes have the potential to generate cyclic siloxanes during storage and / or during or after use. However, dendritic siloxane oligomers have the potential to replace D5 without this potential to generate cyclic siloxanes. PCT Patent Publication W02020118646 discloses a composition for preparing polyisocyanurate and polyurethane foams. The composition includes a branched siloxane comprising at least three trimethylsiloxy groups.SUMMARY

[0004] This invention provides a method for preparing a product comprising 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane). The method comprises: 1) mixing 1, 1,1, 3, 5,5,5-heptamethyltrisiloxane and tris(pentafluorophenyl)borane, thereby preparing a first mixture; 2) mixing trimethyl orthoformate and additional tris(pentafluorophenyl)borane, wherein the additional tris(pentafluorophenyl)borane, thereby preparing a second mixture; and3) feeding the second mixture into the first mixture, thereby forming the product comprising 3,3'-oxybis( 1,1, 1 ,3,5,5,5-heptamethyltrisiloxane).DETAILED DESCRIPTION

[0005] A method for preparing a product comprising 3,3'-oxybis(l.l,l,3,5,5,5-heptamethyltrisiloxane) is provided herein. The method comprises:1) mixing A) 1,1,1,3,5,5,5-heptamethyltrisiloxane and C) tris(pentafluorophenyl)borane, wherein C) the tris(pentafluorophenyl)borane is used in an amount sufficient to provide 50 ppmby weight to 200 ppm by weight based on A) the 1,1,1,3,5,5,5-heptamethyltrisiloxane. thereby preparing a first mixture;2) mixing B) trimethyl orthoformate and additional C) tris(pentafluorophenyl)borane, wherein C) the additional tris(pentafluorophenyl)borane is used in an amount sufficient to provide 100 ppm by weight to 300 ppm by weight based on B) the trimethyl orthoformate, thereby preparing a second mixture; and3) feeding the second mixture into the first mixture under conditions to control temperature at 10 °C to 30 °C, thereby forming the product comprising 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane). The method may optionally further comprise one or more additional steps. For example, the method may further comprise step 4): mixing the product at 23 °C ± 3 °C for at least 1 hour. Without wishing to be bound by theory, it is thought that step 4) may allow for increasing yield, if unreacted starting materials are present after step 3). The method may optionally further comprise step 5): purifying the 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane). Step 5) may be performed after step 3) or after step 4), when step 4) is present.

[0006] The 1,1,1,3,5,5,5-heptamethyltrisiloxane used in the method has formula:commercially available from various sources such as Sigma- Aldrich, Inc. of St. Louis, Missouri, USA; TCI America division of Tokyo Chemical Industry, of Portland, Oregon, USA; Oakwood Chemical of West Columbia, South Carolina, USA; and Fisher Scientific of Waltham, Massachusetts, USA.

[0007] The trimethyl orthofomiate used in the method has formula:Trimethyl orthoformate is commercially available from various sources including Sigma-Aldrich, Inc. and Fisher Scientific.

[0008] The tris(pentafluorophenyl)borane used in the method has formulaTris(pentafluorophenyl)borane is commercially available from various sources, such as Sigma-Aldrich, Inc., TCI America, and Fisher Scientific. Tris(pentafluorophenyl)borane may be prepared by known methods, such as those disclosed in US Patent US5744646.

[0009] These starting materials used in the method may be combined by mixing in a reactor with heating and cooling means, such as a jacket. An inert gas, such as nitrogen or argon, may be used to reduce oxygen content in the reactor. The tris(pentafluorophenyl)borane may be dissolved in a solvent (e.g., an aromatic hydrocarbon such as benzene, toluene, or xylene) to aid mixing and delivery. Alternatively, the 1,1,1,3,5,5,5-heptamethyltrisiloxane; tris(pentafluorophenyl)borane; and the solvent may be combined in the reactor to form the first mixture.

[0010] The second mixture comprising the trimethyl orthoformate and the additional tris(pentafluorophenyl)borane (and optionally a solvent) may be added to the first mixture continuously or in aliquots. For example, the second mixture may be added over 50 minutes to 90 minutes, alternatively 70 minutes. The second mixture may be added to the first mixture with heating or cooling, e.g., at a temperature of 10 °C to 30 °C.

[0011] The method described herein may optionally further comprise one or more additional steps as described above. Step 5) purifying the 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane) may comprise neutralizing the catalyst by adding a neutralizing agent for the tris(pentafluorophenyl)borane catalyst after preparing the product comprising 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane). Purifying may comprise filtration to remove the neutralizing agent, when used. Any suitable neutralizing agent may be used. Suitable neutralizing agents for tris(pentafluorophenyl)borane catalyst, such as metal oxides orhydroxides (e.g., neutral alumina). Alternatively, purifying may comprise removing an unreacted starting material, a side product, and / or solvent, when used, such as by stripping, distillation, or evaporation. The resulting product comprises 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane) with good yield and purity.EXAMPLES

[0012] The following examples are provided to illustrate the invention to one skilled in the art and are not to be construed so as to limit the scope of the invention set forth in the claims. The starting materials used in this invention are summarized below in Table 1.Table 1 - Starting Materials

[0013] In this Comparative Example 1, 0.76g TMOF was added into a 1 / 2-oz. vial and stirred at ~20 °C. 39 pl of BCF / toluene solution (4.825%) was added into the vial (to make a solution containing BCF at 300 ppm). 4.79 g of MD’M was added into the vial slowly (over 10 minutes). A molar ratio TMOF / MD M = 1 / 3. The vial was not capped but covered with Al foil to minimize moisture exposure. No sign of reaction was observed for 7 hours (no gas generation and no exotherm). Stirring was continued at ~20 °C for a total of 48 hours. 20 mg of triphenylamine was added to quench the BCF catalyst. GC-FID results showed MD’M converted to 3-methoxy-l,l,l,3,5,5,5-heptamethyltrisiloxane (MDOMeM) and M2TTM2 at -60 / 40 GC peak area ratio. Formation of M2TTM2 generated CH4 gas and heat. It was unknown when the conversion to M2TTM2 happened after the initial 7 hours where no sign of reaction was observed. With this order of addition of the starting materials, commercial scale production would be impractical due to long batch time, and the resulting yield and purity were both undesirably low.

[0014] In this Comparative Example 2, reaction of DME with MD’M was performed as follows: 10.0 g MD’M was charged into a 1-oz. vial. With stirring at -20 °C, 80 pl of BCF catalyst solution (4.825% BCF in toluene) was added into the vial, with a target of 300 ppm BCF. DME was added into the vial dropwise. No sign of reaction (no exotherm and no gas generation) was observed. Another 80 pl of BCF catalyst solution (4.825% in toluene) wasadded into the vial so that BCF totaled 600 ppm. The reaction was very slow at ~20 °C.

[0015] The vial was heated to 60 °C on a hotplate, and fast reaction was observed fast reaction. DME addition continued drop wise to a total of 1.01 g within ~3 minutes. Stirring continued at 60 °C for 2 hours until no more gas bubble generation was observed. The vial was then cooled to ~20 °C.

[0016] In this Comparative Example 3, reaction of Diethylene glycol methyl ethyl ether with MD’M was performed as follows: 10.0 g MD’M was charged into a 1-oz. vial. With stirring at ~20 °C, 80 pl of BCF catalyst solution (4.825% BCF in toluene) was added into the vial, with a target 300 ppm BCF. DEGME was added into the vial dropwise. No sign of reaction (no exotherm and no gas generation) was observed. Another 80 pl of BCF catalyst solution (4.825% in toluene) was added into the vial so that BCF totaled 600 ppm. No reaction was observed at ~20 °C.

[0017] The vial was heated to 60 °C on a hotplate, and fast reaction was observed. The addition of Diethylene glycol methyl ethyl ether continued to a total of 1.08 g drop wise within ~3 minutes. Stirring continued at 60 °C for 2 hours. No more gas bubble generation was observed, and the vial was cooled to ~20 °C.

[0018] In this Comparative Example 4, the procedure of Liao, Brook, et al. “Living synthesis of silicone polymers controlled by humidity’’, European Polymer Journal, Volumel07. Pages 287-293 was performed. Yield was only 50 %, and purity by GC-FID was 95 area %.Comparative Example 4 showed that the reaction was difficult to control, and without wishing to be bound by theory it is thought that water deactivated the catalyst. The yield reported by Brook et al. was not achievable by practicing the process as described in the reference.

[0019] In this Working Example 1 , 856.0 g of MD’M was charged into a 2000 ml flask equipped with mechanical stirrer, thermal couple, and N2 blanket. At 22 °C, 3.4 g BCF / toluene solution (5.38 % BCF with balance as toluene) was added into the flask, and a mixture of 70.2 g of trimethyl orthoformate (TMOF) and 3.9 g BCF / toluene solution (5.38 %) was added to the flask slowly via a peristaltic pump, i.e., at an addition rate of 1.0-1.2 ml / min. Temperature was controlled at 15 to 20 °C by dry ice cooled heat block. Feed time was 70 minutes. The mixture was stirred at 22 °C for 60 minutes, and then volatiles were removed via rotary evaporator at 80 °C and 1.5 torr to 2.0 torr for 30 minutes. 866.1g product was collected. GC-FID analysis indicated that yield was 98.1 area %, and purity was 99.6 area %, of the 3,3'-oxybis( 1,1, 1 ,3,5,5,5-heptamethyltrisiloxane).Table 2< <

[0020] GC-MS analysis indicated the products from the Comparative Examples 2 and 3 contained various impurities shown below in Table 3. Comparative Examples 2 and 3 demonstrated that lower yield and lower purity of M2TTM2 were obtained using DME and DGME instead of trimethyl orthoformate as in Working Example 1.Table 3 - Impurities in Comparative Examples 2 and 3""<>"

[0021] In Table 3, the species detected in comparative example 2 made with DME were 266, 310, 458, 502, 606, and 754. The species detected in the comparative example 3 made with DEGME were 238, 266. 282, 310. 430, 458, 502, 578, 606, and 650.Test Methods

[0022] Gas Chromatography (GC) Analysis was performed as follows: The GC analysis was performed using a Hewlett Packard HP 6890 Series GC System. To a glass GC syringe 0.3 pl of the test material was added. The sample was manually injected into the GC inlet and then the start button was pressed. The mn conditions as well as the column type can be found below.| Outlet Pressure | Vacuum |

[0023] Gas Chromatography Mass Spectrometry (GC-MS) Analysis was performed as follows: The GC-MS analysis was performed using an Agilent 7890 column program: 40°C (1 min) - 315°C (10 min) @ 10°C / min. The column, inlet, and detector information can be found below.&Industrial Applicability

[0024] The examples above demonstrate that unexpectedly high yield (> 98% and high purity > 99 GC area %) of the 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane) can be achieved using the method of this invention.

[0025] The 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane) prepared as described herein may be used for preparing polyisocyanurate and polyurethane foams, e.g., as a nucleator, as described, for example, in PCT Patent Application Publication WO2020118646.Definitions and Usage of Terms

[0026] Any feature or aspect of the invention may be used in combination with any other feature or aspect recited herein. All amounts, ratios, and percentages herein are by weight, unless otherwise indicated by the context of the specification. The articles ‘a’, ‘an’, and ‘the’ each refer to one or more, unless otherwise indicated by the context of specification. The singular includes the plural unless otherwise indicated by the context of the specification. TheSUMMARY and ABSTRACT are hereby incorporated by reference. The amounts of all starting materials in a composition total 100%. Any feature or aspect of the invention may be used in combination with any other feature or aspect recited herein. The abbreviations used herein have the definitions in Table A.Table A - Abbreviations

[0027] In this application, 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane) refers to the>compound of formula:

[0028] It is to be understood that the appended claims are not limited to express and particular compounds, compositions, or methods described in the detailed description, which may varyamong embodiments, which fall within the scope of the appended claims. With respect to any Markush groups relied upon herein for describing particular features or aspects of various embodiments, different, special, and / or unexpected results may be obtained from each member of the respective Markush group independent from all other Markush members. Each member of a Markush group may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims.

Claims

CLAIMS:

1. A method for preparing a product comprising 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane), wherein the method comprises:1) mixing A) l,LL3,5,5,5-heptamethyltrisiloxane and C) tris(pentafluorophenyl)borane, wherein C) the tris(pentafluorophenyl)borane is used in an amount sufficient to provide 50 ppm by weight to 200 ppm by weight based on A) the 1 , 1 , 1 ,3,5,5,5-heptamethyltnsiloxane, thereby preparing a first mixture;2) mixing B) trimethyl orthoformate and additional C) tris(pentafluorophenyl)borane, wherein C) the additional tris(pentafluorophenyl)borane is used in an amount sufficient to provide 100 ppm by weight to 300 ppm by weight based on B) the trimethyl orthoformate, thereby preparing a second mixture; and3) feeding the second mixture into the first mixture under conditions to control temperature at 10 °C to 30 °C, thereby forming the product comprising 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane).

2. The method of claim 1, further comprising: 4) mixing the product at 23 °C ± 3 °C for at least 1 hour.

3. The method of claim 1 or claim 2, further comprising 5) purifying the 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane).

4. The method of any one of claims 1 to 3, further comprising dissolving the tris(pentafluorophenyl)borane in a solvent to form a catalyst solution before step 1), before step 2), or both.

5. The method of any one of claims 1 to 4, wherein feeding the second mixture is performed over 50 to 90 minutes, continuously or in aliquots, in step 3).

6. The method of any one of claims 1 to 5, wherein step 5) comprises neutralizing the catalyst by adding a neutralizing agent for the tris(pentafluorophenyl)borane catalyst after preparing the product comprising 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane); and thereafter removing the neutralizing agent.

7. The method of any one of claims 1 to 6, wherein step 5) comprises stripping.distillation, and / or evaporation.

8. A product comprising > 99 % 3,3'-oxybis(l,l,l,3,5,5,5-heptamethyltrisiloxane) prepared by the method of any one of claims 1 to 7.

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