Cyanoethyltrimethoxysilane Manufacturing Process

Abstract

The process for preparing cyanoethyltrimethoxysilane is carried out through the transesterification of cyanoethyltriethoxysilane with methanol in the presence of a catalyst.Cyanoethyltrimethoxysilane is useful as an adhesion promoter, coupling agent, or crosslinking agent.Cyanoethyltrimethoxysilane may be incorporated into polyorganosiloxane sealant compositions.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 63 / 285,546, filed December 3, 2021. U.S. Provisional Patent Application No. 63 / 285,546 is incorporated herein by reference.

[0002] The present invention relates to a process for producing cyanoethyltrimethoxysilane. More specifically, the present invention relates to a process for producing cyanoethyltrimethoxysilane by transesterification of cyanoethyltriethoxysilane.

[0003] Introduction Cyanoethyltrimethoxysilane (CETMS) is useful as an adhesion promoter or coupling agent in siloxane compositions, such as room temperature vulcanizable (RTV) polyorganosiloxane sealant compositions. CETMS can be prepared by the hydrosilylation reaction of acrylonitrile with trichlorosilane, followed by methoxylation. CETMS can also be prepared by the hydrosilylation reaction of trimethoxysilane with acrylonitrile. However, these processes have drawbacks with the result that CETMS is not widely available on a commercial scale. Summary of the Invention

[0004] The process for making cyanoethyltrimethoxysilane involves combining cyanoethyltriethoxysilane, methanol, and an acid catalyst. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] More specifically, the process for producing CETMS is: 1) combining starting materials including (A) cyanoethyltriethoxysilane (CETES), (B) a stoichiometric excess of methanol, and (C) an acid catalyst, thereby forming a transesterification reaction mixture; Optionally, 2) adding (D) activated carbon to the transesterification reaction mixture; and 3) removing materials from the transesterification reaction mixture, the materials including methanol, ethanol, and (C) the acid catalyst; and 4) repeating steps 1) to 3) one or more times (adding methanol and (C) the acid catalyst a total of at least two times, followed by removing methanol, ethanol and the catalyst).

[0006] In the process for producing cyanoethyltrimethoxysilane, the transesterification reaction between CETES and methanol may proceed according to the transesterification reaction scheme shown below.

[0007] [ka] In the formula of the alkoxysilane product, when x=0, the formula is CETMS. However, partially methoxylated species, such as cyanoethyl-, diethoxy-, monomethoxysilane (when x=2) and / or cyanoethyl-, monoethoxy-, dimethoxysilane (when x=1), may also be formed during the process described herein. In the formula of the dimer in this reaction scheme, each R is independently selected from the group consisting of methyl and ethyl. Dimers are by-products that may be formed during the process described herein, and increased formation of dimers adversely affects the yield of CETMS. It is desirable to operate the reaction in such a way that the ethoxy groups in CETES are highly converted to methoxy groups, resulting in high purity CETMS, and with only a small amount of dimer formation.

[0008] In step 1) of the process described herein, (A) cyanoethyltriethoxysilane and (B) methanol are used in sufficient amounts to provide a stoichiometric excess of methanol. The amount of (A) cyanoethyltriethoxysilane and (B) methanol may be at least 5:1 (B):(A) (molar ratio), alternatively at least 15:1, while at the same time, the (B):(A) ratio may be up to 30:1, alternatively up to 15:1. Alternatively, the (B):(A) ratio may be 5:1 to 30:1, alternatively >5:1 to 30:1, alternatively 15:1 to 30:1. Without wishing to be bound by theory, it is believed that step 1) may be carried out at room temperature or at an elevated temperature, such as up to 70° C. Alternatively, the temperature may be from 21° C. to 70° C. The time of the transesterification reaction in step 1) is sufficient to reach equilibrium. For example, at room temperature, the time may be from 1 hour to 4 hours. However, the exact time will depend on various factors such as the temperature selected and the choice and amount of (C) acid catalyst. Without wishing to be bound by theory, it is believed that carrying out the transesterification reaction in step 1) at room temperature can be efficient in terms of time, energy, and costs associated with heating and cooling. The use of an acid catalyst can provide the advantage of allowing for a rapid reaction at room temperature, which minimizes time and operating costs. The reaction may optionally be carried out under elevated temperatures. Furthermore, step 1) may be carried out under conditions that minimize or eliminate the presence of moisture. Without wishing to be bound by theory, it is believed that moisture contamination may initiate a side reaction to form a dimer, which reduces the yield of CETMS.

[0009] The starting material (C), the acid catalyst, may be selected from the group consisting of hydrogen halides of formula HX (wherein X is Cl, Br or I), sulfonic acids (e.g., toluenesulfonic acid or trifluoromethanesulfonic acid), and ion exchange resins. Alternatively, the (C) acid catalyst may be a hydrogen halide, or the acid catalyst may be HCl. When the (C) acid catalyst is a hydrogen halide, e.g., HCl, the hydrogen halide (e.g., HCl) may be used in an amount of at least 1 ppm, alternatively at least 5 ppm, alternatively at least 10 ppm, alternatively at least 30 ppm, based on the sum of the weight of (A) CETES and the weight of (B) MeOH, while at the same time the amount of hydrogen halide (e.g., HCl) may be up to 100 ppm, alternatively up to 50 ppm, alternatively up to 30 ppm. Alternatively, the amount of hydrogen halide (e.g., HCl) may be from 10 ppm to 100 ppm, alternatively from 10 ppm to 50 ppm, alternatively up to 30 ppm, based on the same basis. Alternatively, if ion exchange resin is used, the amount may be at least 0.1%, or at least 0.5% solids relative to the liquid, while at the same time the amount may be up to 30%, on the same basis. Alternatively, the amount of ion exchange resin may be 0.1%-30%.

[0010] The starting materials used in step 1) of the process are known in the art and commercially available. CETES is available from Gelest Inc. (Morrisville, Pennsylvania, USA). MeOH and HCl are available from a variety of sources, including Sigma-Aldrich, Inc. (St. Louis, Missouri, USA). The ion exchange resins for use herein may be strong and weak acid cation exchange resins, where the ionic form of the resin is not hydrogen (H+). Such ion exchange resins are commercially available, for example DOWEX™ Monosphere 2030, DOWEX™ MARATHON™ 1200 (Na+ form), and AMBERLITE IR122 Na from TDCC.

[0011] Combining the starting materials in step 1) may be carried out by any convenient means, such as mixing, batchwise or continuously. Mixing may be carried out in conventional equipment, such as a batch reactor equipped with an agitator, as well as optional heating means, such as a jacket. Alternatively, the process may be carried out in a packed bed reactor, for example, when a solid catalyst, such as an ion exchange resin, is used, the reactor may be filled with (C) an acid catalyst, and / or when step 2) is present, for example, activated carbon is used.

[0012] Step 2) of the process involves combining (D) activated carbon with the transesterification reaction mixture prepared in step 1). Step 2) is optional. However, when used, step 2) can be carried out at room temperature, for example, by mixing the activated carbon with the transesterification reaction mixture prepared in step 1) for a time sufficient to adsorb the acid HCl from the transesterification reaction mixture. The exact time depends on various factors, such as the size of the vessel used in step 2) (which may be the same as the reactor used in step 1), but the time may be at least 1 hour, alternatively at least 2 hours, alternatively at least 4 hours, alternatively at least 8 hours, alternatively at least 16 hours, while at the same time, the time may be up to 48 hours, alternatively up to 24 hours, alternatively up to 16 hours. Step 2) can be carried out under conditions that minimize or exclude moisture.

[0013] When step 2) is present, (D) the activated carbon may be selected from the group consisting of (D1) bituminous activated carbon, (D2) coconut activated carbon having an iodine value of > 1200 mg / g, and (D3) a combination of both (D1) and (D2). (D1) bituminous activated carbon and (D2) coconut activated carbon are known in the art and are commercially available from various sources such as General Carbon Corporation (Paterson, New Jersey, USA) or Calgon Carbon (Pittsburgh, Pennsylvania, USA). The bituminous activated carbon may have an iodine value of at least 500 mg / g(min), alternatively at least 600 mg / g(min), alternatively at least 750 mg / g(min), alternatively at least 850 mg / g(min), alternatively at least 900 mg / g(min), while at the same time, the bituminous activated carbon may have an iodine value of up to 1200 mg / g(min), alternatively up to 1100 mg / g(min), alternatively up to 1,000 mg / g(min), alternatively up to 950 mg / g(min). Alternatively, the iodine value of the bituminous activated carbon may be 600 mg / g(min) to 1200 mg / g(min), alternatively 750 mg / g(min) to 1200 mg / g(min), alternatively 900 mg / g(min) to 1200 mg / g(min), alternatively 900 mg / g(min) to 1050 mg / g(min). The iodine value of the coconut activated carbon may be ≧1200 mg / g(min), alternatively 1200 mg / g(min) to 1500 mg / g(min), alternatively 1200 mg / g(min) to 1300 mg / g(min).

[0014] Examples of bituminous activated carbon include GC 12x40, a virgin activated carbon in granular form having an iodine number of 900 mg / g(min) and a density of 0.47-0.53 g / cc, available from General Carbon Corporation, and CAL™ 12x40 granular activated carbon, a re-agglomerated metallurgical grade bituminous coal having an iodine number of 1000 mg / g(min), available from Calgon Carbon. Other bituminous activated carbons from Calgon Carbon include CPG™ LF 12x40 with an iodine value of 950 mg / g(min), FILTRASORB™ 300M with an iodine value of 900 mg / g(min), FILTRASORB™ 400M with an iodine value of 1000 mg / g(min), HPC MAXX with an iodine value of 900 mg / g, and SGL 8x20, a granular activated carbon made from bituminous coal combined with a binder and with an iodine value of 900 mg / g(min). Coconut activated carbons include OLC Plus 12x30 with an iodine value of 1200 mg / g(min) and a density of 0.45 g / cc, also available from Calgon Carbon.

[0015] If step 2) is present (i.e., activated carbon is used), the process may further include treating the activated carbon prior to use in step 2). Treatment may be performed, for example, to dry the activated carbon (e.g., to remove all or a portion of any adsorbed moisture to minimize the possibility of hydrolysis of the alkoxysilane product when the carbon contacts the transesterification reaction mixture). For example, the activated carbon may be heated to a temperature above the boiling point of water (e.g., >100°C, alternatively >100°C to 200°C, alternatively 120°C to 160°C) for a time sufficient to remove all or a portion of the water, e.g., for 1 minute to 24 hours. The activated carbon may be heated under ambient or reduced pressure. The activated carbon may be heated and stored under an inert atmosphere, such as nitrogen, prior to use in step 2).

[0016] Step 3) of the process involves removing materials including (excess) unreacted (B) methanol, ethanol (produced as by-products), and (C) acid catalyst from the transesterification reaction mixture. Step 3) may be carried out by any convenient means. Step 3) may include, for example, filtration to remove solid materials such as ion exchange resins when used as (C) acid catalyst, and / or activated carbon when present in step 2). Step 3) may also include stripping and / or distillation under heat and optionally reduced pressure, which can remove methanol, ethanol, and liquid acid catalyst such as HCl.

[0017] Step 4) of the process involves repeating steps 1)-3) one or more times. Step 4) may involve repeating 1)-3) at least once, or alternatively 1-4 times. Without wishing to be bound by theory, it is believed that repeating steps 1)-3) of adding and then removing methanol and acid catalyst too many times (e.g., more than five times (or more than five times), totaling 6-7 times or more, may result in the formation of undesirable amounts of dimers and / or increased costs that make the process impractical on a commercial scale. Alternatively, step 4) may involve repeating steps 1)-3) once or twice, especially when step 2) is present. Without wishing to be bound by theory, it is believed that due to thermodynamic equilibrium limitations and the higher volatility of methanol compared to ethanol, a back reaction may occur during step 3) (e.g., via stripping and / or distillation) via reaction of CETMS (when x=0 in the alkoxylation product formula shown above) or partially methoxylated species (when x=1 or 2) with the EtOH by-product (which cannot be removed until all or most of the lower boiling MeOH has first been removed). Furthermore, the inventors have surprisingly found that treating the transesterification reaction mixture with activated carbon in step 2) minimizes this back reaction. Since each repetition of steps 1)-3) can add to the cost of the process, it is desirable to minimize the number of repetitions in step 4 for efficiency, provided that the yield and purity of the CETMS product is achieved.

[0018] The above process may optionally further comprise one or more additional steps. For example, after step 4), the process may further comprise 5) treating the CETMS with activated carbon. Without wishing to be bound by theory, step 5) may be carried out by pumping the CETMS through a vessel, such as a drum or bed, containing activated carbon, or the activated carbon may be added to the vessel used in step 4) and then filtered out from the product. The activated carbon used in step 5) may be as described above with respect to step 2). When steps 2) and / or 5) are present, the process may optionally further comprise drying the activated carbon before use.

[0019] The above process is carried out according to the following formula:

[0020] [ka] The conversion of the ethoxy groups of the CETES starting material to methoxy groups, as measured by the test methods described below and used in the examples, may be at least 90 GC area %, alternatively at least 91 GC area %, alternatively at least 92 GC area %, alternatively at least 93 GC area %, alternatively at least 94 GC area %, while at the same time the conversion may be up to 100 GC area %, alternatively up to 99 GC area %, alternatively up to 98 GC area %, alternatively up to 97 GC area %, alternatively up to 96 GC area %. The purity of the CETMS, as measured by the test methods described below and used in the examples, may be at least 72 GC area %, alternatively at least 81 GC area %, alternatively at least 86 GC area %, alternatively at least 89 GC area %, alternatively at least 90 GC area %, while at the same time the purity of the CETMS may be up to 100 GC area %, alternatively up to 98 GC area %, alternatively up to 95 GC area %, alternatively up to 92 GC area %, alternatively up to 90 GC area %. The amount of dimer may be 0, alternatively 1% to 10% by weight, alternatively 1.5% to 9% by weight, alternatively 1.8% to 6% by weight, alternatively 2% to 3% by weight. However, the amount of dimer may vary depending on whether step 2) is present. For example, the amount of dimer may be 1% to 3% by weight, alternatively 1.5% to 2% by weight, alternatively 1.8% by weight, if step 2) of the process is omitted (no treating agent is used). If a treating agent (e.g., activated carbon) is used, the amount of dimer may be 5% to 10% by weight, alternatively 6% to 9% by weight.

[0021] The composition containing CETMS prepared as above can be used in polyorganosiloxane compositions, such as room temperature vulcanizable organopolysiloxane compositions. Room temperature vulcanizable organopolysiloxane compositions are known in the art, such as those disclosed in U.S. Patent No. 4,483,973 to Lucas et al., U.S. Patent No. 5,962,559 to Lucas et al., U.S. Patent No. 7,550,548 to Hatanaka et al., U.S. Patent No. 7,674,871 to Koch et al., U.S. Patent Application Publication No. 2007 / 0173597 to Williams et al., and PCT Patent Application Publication No. WO2007 / 024792. CETMS can function as an adhesion promoter, coupling agent, and / or crosslinking agent in polyorganosiloxane compositions. Alternatively, CETMS can be added to commercially available room temperature vulcanizable sealants, such as XIAMETER™ SLT-5200 from DSC. EXAMPLES

[0022] These examples are intended to illustrate the invention to one of ordinary skill in the art and should not be construed as limiting the invention as set forth in the claims. Materials used herein are listed in Table 1.

[0023] [Table 1]

[0024] In this example, the samples of activated carbon were treated prior to use as follows: Each sample of activated carbon was dried overnight at 140° C. in a vacuum oven prior to use. The carbon was then dried over N 2 It was stored in a purged glove box to prevent water from being adsorbed from the air. Without wishing to be bound by theory, it is believed that the level of moisture in the carbon can affect reaction kinetics and in some cases increase dimer levels when carrying out the processes described herein.

[0025] In this Example 1, 172 g of MeOH was added to 234 g of CETES in a 1 L round bottom flask under stirring with a stir bar. Then, 115 uL of 3M HCl in MeOH was added to the flask. The transesterification reaction was completed after 1 hour at room temperature. The reaction mixture was then distilled under a vacuum of 75-150 mmHg at 30-50°C to remove MeOH and EtOH, followed by the addition of fresh MeOH and catalyst. This process of distillation and fresh MeOH addition was continued four more times (for a total of five MeOH additions), after which the purity of CETMS reached 81%.

[0026] In this Example 2a, 273 g of MeOH was added to 173 g of CETES in a 1 L flask under stirring with a stir bar. Then, 115 uL of 3M HCl in MeOH was added to the flask and the reaction was completed after 1 hour at room temperature. The reaction mixture was then distilled at 30-50°C under a vacuum of 75-150 mmHg to remove MeOH and EtOH, followed by the addition of fresh MeOH and catalyst. This process of fresh MeOH addition and distillation was repeated two more times after which the purity of CETMS reached 72%. The contents of the flask were analyzed after each distillation.

[0027] In this Example 2b, Example 2a was continued with another addition of MeOH (4 MeOH additions in total). After the same reaction and distillation conditions, the material reached 90% purity of CETMS.

[0028] In this Example 2c, Example 2b was continued with additional additions of MeOH (a total of 5 additions of MeOH). After the same reaction and distillation conditions, the material reached 95% purity of CETMS.

[0029] In this Example 3, 336 g of MeOH was added to 76 g of CETES in a 1 L flask under stirring with a stir bar. 115 μL of 3M HCl was then added to the flask and the reaction was completed after 1 h at room temperature. The reaction mixture was then distilled at 30-50° C. under a vacuum of 75-150 mmHg to remove MeOH and EtOH, followed by the addition of more MeOH and catalyst. This process of fresh MeOH addition and distillation was repeated three more times after which the purity of CETMS reached 94%. The contents of the flask were analyzed after each distillation.

[0030] In this Example 4a, 273 g of MeOH was added to 173 g of CETES in a 1 L flask under stirring with a stir bar. Then, 0.11 g of 25 wt% NaOMe was added to the reactor and the reaction was completed after 1 hour at room temperature. The reaction mixture was then distilled at 30-50°C under a vacuum of 75-150 mmHg to remove MeOH and EtOH, followed by the addition of more MeOH and NaOMe as a catalyst. This process of MeOH addition and distillation was repeated two more times, after which the purity of CETMS reached 79%. The contents of the flask were analyzed after each distillation.

[0031] In this Example 4b, Example 4a was continued with another addition of MeOH (4 MeOH additions in total). After the same reaction and distillation conditions, the material reached 90% purity of CETMS.

[0032] In this Example 5, 273 g of MeOH was added to 173 g of CETES in a 1 L flask under stirring with a stir bar. Then, 115 μL of 3M HCl in MeOH was added to the flask and the reaction was completed after 1 hour at room temperature. A molar equivalent of NaOMe was added to the reaction mixture and stirred for 1 hour to neutralize the HCl. The neutralization salt was removed from the reaction mixture using 6 μm filter paper and a Buchner funnel. The filtered material was then distilled under a vacuum of 75-150 mmHg at 30-50°C to remove EtOH and MeOH, followed by the addition of more MeOH and HCl as catalyst. The process of adding fresh MeOH / HCl catalyst, neutralization, filtration, and distillation was continued two more times, after which the purity of CETMS reached 49%. The contents of the flask were analyzed after each distillation.

[0033] In this Example 6, 273 g of MeOH was added to 173 g of CETES in a 1 L flask under stirring with a stir bar. Then, 115 μL of 3M HCl in MeOH was added to the flask and the reaction was completed after 1 hour at room temperature. Then, 0.15 g of NaHCO 3 was added to the reaction mixture and stirred for 1 hour to neutralize the HCl. Salts were removed from the reaction mixture using 6um filter paper and a Buchner funnel. The filtered material was then distilled under vacuum of 75-150mmHg at 30-50°C to remove EtOH and MeOH, followed by the addition of more MeOH and catalyst. NaHCO 3 After continuing the process of addition, filtration, distillation, and addition of fresh MeOH / catalyst two more times, the purity of CETMS reached 53%. The contents of the flask were analyzed after each distillation.

[0034] In this Example 7, 273 g of MeOH was added to 173 g of CETES in a 1 L flask under stirring with a stir bar. 115 uL of 3M HCl in MeOH was then added to the reactor and the reaction was completed after 1 hour at room temperature. 20 g of Cal 12x40 carbon was added to the reaction mixture and stirred overnight. Carbon was removed from the reaction mixture using a 0.45 um cellulose-based Nalgene disposable filter. The filtered material was then distilled under 75-150 mmHg vacuum at 30-50°C to remove EtOH and MeOH, followed by the addition of more MeOH and catalyst. The process of carbon addition, filtration, distillation, and addition of fresh MeOH / catalyst was continued two more times, after which the purity of CETMS reached 89%. The contents of the flask were analyzed after each distillation.

[0035] In this Example 8a, 273 g of MeOH was added to 173 g of CETES in a 1 L flask under stirring with a stir bar. 115 uL of 3M HCl in MeOH was then added to the reactor and the reaction was completed after 1 hour at room temperature. 20 g of OLC Plus 12x30 carbon was added to the reaction mixture and stirred overnight. Carbon was removed from the reaction mixture using a 0.45 um cellulose-based Nalgene disposable filter. The filtered material was then distilled under 75-150 mmHg vacuum at 30-50°C to remove EtOH and MeOH, followed by the addition of more MeOH and catalyst. After another round of the process of carbon addition, filtration, distillation, and new MeOH / catalyst addition, the purity of CETMS reached 86%.

[0036] In this Example 8b, the process of carbon addition, filtration, distillation, and addition of fresh MeOH / catalyst in Example 8a was followed one more time (total of 3), resulting in 92% pure CETMS.

[0037] [Table 2]

[0038] In this Example 9, 172 g of MeOH was added to 234 g of CETES in 1 L under stirring with a stir bar. 115 uL of 3M HCl was then added to the flask and the reaction was completed after 1 hour at room temperature. The reaction mixture was then distilled under a vacuum of 75-150 mmHg at 30-50°C to remove MeOH and EtOH. After distillation, the material reached a purity of 10% CETMS.

[0039] In this Example 10, 273 g of MeOH was added to 173 g of CETES in a 1 L flask under stirring with a stir bar. 115 uL of 3M HCl was then added to the flask and the reaction was completed after 1 hour at room temperature. The reaction mixture was then distilled under a vacuum of 75-150 mmHg at 30-50°C to remove MeOH and EtOH. After distillation, the material reached a purity of 23% CETMS.

[0040] In this Example 11, 273 g of MeOH was added to 173 g of CETES in a 1 L flask under stirring with a stir bar. 0.11 g of 25 wt% NaOMe was then added to the flask and the reaction was completed after 1 hour at room temperature. The reaction mixture was then distilled under a vacuum of 75-150 mmHg at 30-50°C to remove MeOH and EtOH. After distillation, the material reached a purity of 21% CETMS.

[0041] In this Example 12, 273 g of MeOH was added to 173 g of CETES in a 1 L flask under stirring with a stir bar. Then, 2 g of Dowex Monosphere 2030 (Dowex) was added to the flask and the reaction was completed after 1 hour at room temperature. Dowex was removed from the reaction mixture using 6 um filter paper and a Buchner funnel. The filtered material was then distilled under a vacuum of 75-150 mmHg at 30-50°C to remove EtOH and MeOH. After distillation, the material reached a purity of 20% CETMS.

[0042] In this Example 13, 172 g of MeOH was added to 234 g of CETES in a 1 L flask under stirring with a stir bar. 0.35 g of Tyzor Pita SM was then added to the flask and the reaction was completed after 8 hours at room temperature. The material was then distilled under a vacuum of 75-150 mmHg at 30-50°C to remove EtOH and MeOH. After distillation, the material reached a purity of 9% CETMS.

[0043] In this Example 14, 172 g of MeOH was added to 234 g of CETES in a 1 L flask under stirring with a stir bar. 0.4 g of Ti(IV) butoxide was then added to the flask and the reaction was completed after 10 hours at room temperature. The material was then distilled under a vacuum of 75-150 mmHg at 30-50°C to remove EtOH and MeOH. After distillation, the material reached a purity of 9% CETMS.

[0044] The results of the catalyst screening in Examples 9-14 are shown below in Table 3. HCl and ion exchange resins gave the highest purity of CETMS and the least dimer formation under the conditions tested.

[0045] [Table 3]

[0046] In this Example 15, a source solution of 520 g MeOH and 235 g CETES was added to a 2 L HDPE bottle. 50 g was then taken from the source solution to retain the control sample. 0.2 g 3M HCl was then added to the source solution and mixed with a stir bar for 1 hour. 50 g was then dispensed into thirteen 4 oz HDPE bottles and 2.5 g of each carbon or activated alumina shown in Table 4 was added to each bottle. The material was then placed on a wrist action shaker overnight. A 0.45 μm PTFE syringe filter was used to remove the carbon or alumina. The filtered material was then titrated to determine chloride content.

[0047] [Table 4]

[0048] Without wishing to be bound by theory, it is believed that residual acids, such as HCl, in the transesterification reaction mixture prior to removal of volatiles, for example by stripping or distillation, promote the formation of CETES while volatile removal is occurring due to Le Chatelier's principle of chemical equilibrium. Because methanol is removed first and the transesterification reaction mixture contains ethanol and catalyst, the reverse reaction to form CETES can occur. Removing the catalyst by effectively adsorbing the residual acid, e.g., HCl, also removes its ability to initiate the reverse reaction during stripping. Table 4 shows a list of carbon screens to figure out which adsorbents (activated carbons) were best at removing HCl by looking at the residual Cl content. The preferred activated carbons were those that reduced the Cl content to <38 ppm (control) without producing a basic solution.

[0049] Test Method Gas chromatography (GC) was used to verify the composition of the materials with an internal standard composition of 1 wt% nonane in acetonitrile. All reported compositions are based on GC area % unless otherwise indicated. An Agilent 7890A GC system equipped with helium carrier gas and FID detector was used with a Restek Rtx-1 30m x 0.25mm x 1um. The flow rate was set at a constant flow rate of 1.5mL / min. The gradient started at 40°C for 2 minutes and then increased to 260°C at 20°C / min. The final temperature of 260°C was held for 2 minutes. Other conditions were as follows: 1. Injection volume 1μL 2. Needle Wash with Acetonitrile for Solvent A and B Washes 3. Split / splitless inlet temperature and FID temperature 260℃ 4. Split injection with a split ratio of 50:1

[0050] Titration was performed using a Metrohm Brinkmann 776 Dosimat to determine chloride levels using BCP indicator and 0.1N KOH. [Industrial Applicability]

[0051] The reaction and subsequent removal of EtOH and other materials may be repeated several times to achieve high conversions of CETES to CETMS via transesterification with MeOH. Due to thermodynamic equilibrium limitations and the higher volatility of MeOH compared to EtOH, during removal of EtOH (e.g., via stripping and / or distillation), a back reaction may occur via reaction of CETMS (when x=0 in the reaction scheme above) or partially methoxylated species (when x=1 or 2) with the EtOH by-product (which cannot be removed until the lower boiling MeOH reactant is first removed).

[0052] The inventors have found that activated carbon treatment dramatically reduces the number of iterations required to achieve good conversion (e.g., as indicated by high purity CETMS) and selectivity (e.g., as indicated by low amounts of dimer). This was particularly surprising because alternative neutralization methods (e.g., addition of sodium methylate or sodium bicarbonate) did not result in the same reductions as shown in the examples above.

[0053] The above examples showed that Ti-based catalysts catalyzed transesterification reactions, but the systems took much longer to reach equilibrium (>8 hours) than acid or base catalysts (<1 hour) under the conditions tested (transesterification reactions carried out at room temperature). Furthermore, the above examples showed that even though base catalysts provide reaction rates comparable to acid catalysts, base catalysts suffer from the drawback of promoting the formation of more impurities (e.g., dimers) than acid catalysts used under the same conditions. Without a catalyst, the transesterification reaction did not occur even at high temperatures (>70°C) under the conditions tested in the examples.

[0054] Definitions and Usage of Terms The amounts of all starting materials in the composition total 100% by weight. The Summary and Abstract of the Invention are incorporated herein by reference. The articles "a", "an", and "the" each refer to one or more, unless otherwise indicated by the context of the specification. The singular includes the plural unless otherwise indicated. Each embodiment or alternative presented herein may be combined with any other embodiment or alternative. The terms "comprising" and its derivatives, such as "comprise" and "comprises", are used herein in their broadest sense to mean and include the notions "including", "include", "consist(ing) essentially of", and "consist(ing) of". The use of "for example", "eg", "such as", and "including" to list examples is not limited to only the examples listed. Thus, "for example" or "such as" means "for example, but not limited to" or "such as, but not limited to," and includes other similar or equivalent examples.

[0055] It is to be understood that the appended claims are not limited to the specific compounds, compositions, or methods described therein for purposes of describing the "Description of the Invention" and may vary among specific embodiments within the scope of the appended claims. With respect to any Markush group relied upon in this specification to describe particular features or aspects of various embodiments, different, special, and / or unexpected results may result from each element of the respective Markush group independent of all other Markush elements. Each element of the Markush group may be relied upon individually and / or in combination to provide adequate support for specific embodiments within the scope of the appended claims.

[0056] The abbreviations used in this application are defined in Table 5 below.

[0057] [Table 5]

[0058] EMBODIMENTS OF THE PRESENT DISCLOSURE In a first embodiment, the process for preparing cyanoethyltrimethoxysilane includes the following steps: 1) (A) cyanoethyltriethoxysilane, (B) a stoichiometric excess of methanol sufficient to provide a molar ratio of methanol:cyanoethyltrimethoxysilane of at least 15:1, i.e., a molar ratio of (B):(A), and (C) combining starting materials comprising (A) cyanoethyltriethoxysilane and (B) methanol in an amount of at least 30 ppm HCl based on the combined weight thereof, thereby producing a transesterification reaction mixture; 2) adding to the transesterification reaction mixture (D1) bituminous activated carbon having an iodine value of at least 900 mg / g; (D2) coconut activated carbon having an iodine value of at least 1200 mg / g; and (D3) Both (D1) and (D2) (D) adding activated carbon selected from the group consisting of: 3) removing materials from the transesterification reaction mixture, the materials including methanol, ethanol, and acid catalyst; and 4) Repeat steps 1) to 3) 1 to 4 times. Includes.

[0059] In a second embodiment, in the process of the first embodiment, the molar ratio of (B):(A) is from 15:1 to 30:1.

[0060] In a third embodiment, in the process of the first or second embodiment, HCl is used in an amount of 30 ppm to 100 ppm.

[0061] In a fourth embodiment, in the process of any one of the first to third embodiments, step 1) is carried out at 21°C to 70°C.

[0062] In a fifth embodiment, in the process of any one of the first to fourth embodiments, step 2) is carried out at 21°C to 70°C.

[0063] In a sixth embodiment, in the process of any one of the first to fifth embodiments, the (D) activated carbon is (D1) a bituminous activated carbon having an iodine value of 900 mg / g(min) to 1200 mg / g(min).

[0064] In a seventh embodiment, in the process of any one of the first to fifth embodiments, the (D) activated carbon is (D2) coconut activated carbon having an iodine value of 1200 mg / g(min) to 1300 mg / g(min).

[0065] In an eighth embodiment, the process of any one of the first to seventh embodiments further comprises treating with (D) activated carbon prior to step 2).

[0066] In a ninth embodiment, in the process of the eighth embodiment, (D) treating the activated carbon includes heating at a temperature of >100°C to 200°C.

[0067] In the tenth embodiment, in the process of any one of the first to ninth embodiments, step 4) repeats steps 1) to 3) once or twice.

[0068] In an eleventh embodiment, a composition comprising cyanoethyltrimethoxysilane is prepared by the process of any one of the first to tenth embodiments.

[0069] In a twelfth embodiment, there is provided the use of the composition of the eleventh embodiment in a polyorganosiloxane sealant composition.

[0070] In a thirteenth embodiment, in the twelfth embodiment, the composition is an adhesion promoter, a coupling agent, or a crosslinking agent.

[0071] In a fourteenth embodiment, the process comprises adding the composition of the eleventh embodiment to a room temperature vulcanizable polyorganosiloxane sealant composition.

Claims

1. 1. A process for preparing cyanoethyltrimethoxysilane, comprising: １） (A) cyanoethyltriethoxysilane, (B) a stoichiometric excess of methanol, and (C) combining starting materials with an acid catalyst, thereby producing a transesterification reaction mixture; Optionally, 2) adding to the transesterification reaction mixture: (D1) bituminous activated carbon; (D2) coconut activated carbon having an iodine value of at least 1200 mg / g; and (D3) Both (D1) and (D2) (D) adding activated carbon selected from the group consisting of: 3) removing materials from the transesterification reaction mixture including methanol, ethanol, and an acid catalyst; and 4) Repeating steps 1) to 3) one or more times. The process includes:

2. 2. The process of claim 1, wherein in step 1) an amount of (A) cyanoethyltriethoxysilane and an amount of (B) methanol are used in a molar ratio (B):(A) of at least 5:1, alternatively from 5:1 to 30:1, alternatively from >5:1 to 30:1, alternatively from 15:1 to 30:

1.

3. 3. The process of claim 1 or claim 2, wherein the (C) acid catalyst is selected from the group consisting of HCl and an ion exchange resin.

4. 4. The process according to claim 1, wherein the (C) acid catalyst is HCl, the HCl is used in an amount of at least 30 ppm based on the sum of the weight of (A) cyanoethyltriethoxysilane and the weight of (B) methanol, and the duration of step 3) is 1 to 4 hours.

5. The process according to any one of claims 1 to 4, wherein step 2) is present.

6. 6. The process of claim 5, wherein the (D) activated carbon is a bituminous activated carbon having an (D1) iodine value of ≧900 mg / g(min).

7. 6. The process of claim 5, wherein the (D) activated carbon is (D2) coconut activated carbon.

8. The process of any one of claims 5 to 7, further comprising treating with (D) activated carbon prior to step 2).

9. The process according to any one of claims 5 to 8, wherein step 4) repeats steps 1) to 3) once or twice.

10. A composition comprising cyanoethyltrimethoxysilane prepared by the process of any one of claims 1 to 9.

11. Use of the composition according to claim 10 in a polyorganosiloxane sealant composition.

12. The use according to claim 11, wherein the composition is an adhesion promoter, a coupling agent, or a crosslinking agent.

13. A method comprising adding the composition of claim 10 to a polyorganosiloxane sealant composition.

14. 14. The method of claim 13, wherein the polyorganosiloxane sealant composition comprises an alkoxy-functional polyorganosiloxane.

15. 14. The method of claim 13, wherein the polyorganosiloxane sealant composition comprises an acyloxy-functional polyorganosiloxane.

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