CA1321398C - Process for producing trialkoxysilanes from the reaction of silicon metal and alcohol - Google Patents
Process for producing trialkoxysilanes from the reaction of silicon metal and alcoholInfo
- Publication number
- CA1321398C CA1321398C CA000562936A CA562936A CA1321398C CA 1321398 C CA1321398 C CA 1321398C CA 000562936 A CA000562936 A CA 000562936A CA 562936 A CA562936 A CA 562936A CA 1321398 C CA1321398 C CA 1321398C
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- Prior art keywords
- silicon metal
- copper
- hydroxide
- reaction
- parts
- Prior art date
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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 System
- C07F7/02—Silicon compounds
- C07F7/025—Silicon compounds without C-silicon linkages
Abstract
ABSTRACT OF THE INVENTION
A process for producing trialkoxysilane by the direct reaction of silicon metal with an alcohol, ROH, in the presence of a catalytically effective amount of copper (II) hydroxide, wherein R
is an alkyl group containing from 1 to 6 carbon atoms.
D-15.591
A process for producing trialkoxysilane by the direct reaction of silicon metal with an alcohol, ROH, in the presence of a catalytically effective amount of copper (II) hydroxide, wherein R
is an alkyl group containing from 1 to 6 carbon atoms.
D-15.591
Description
' J' ~ J ~ 3 Im~roved Process for Producin~ ~ri~lkoxvsil-~es From th~ Reaction of Silicon Metal and Alcohol Field of_the Invention The inventive process generally relates to the production of trialkoxysilanes in ~he catalyzed rsaction of silicon metal with alcohol. In particular, the process entails the reac~ion of silicon metal and alcohol in the presence of a copper (II~ hydroxide ~atalyst. The process exhibits a high ~electivity for trialkoxysilane in that the ratio of trialkoxysilane to te~ra-alkoxysilane produced is hiqh.
Backqround of_the Invention Trialkoxysilanes are used in the production of silane coupling age~ts. U.S. Patent 3,641,077 teaches the preparation of trialkoxysilanes by direct~y reacting silicon metal wi~h alcohol in ~he presence of a catalyst produced by sintering coppe~
and silicon. However, this method results in low yields of trialkoxysilanes.
Patent 3,775,457 teaches the production of alkoxysilanes from the reaction of an alcohol and finely divided silicon metal in the presence of a c~prous chloride catalyst. Although the use of cuprous chloride results in increased yield over that obtained using the sintered copper-silicon catalyst, ~che use of ~uprous chloride ca~alyst also results in the formation of HCl which in turn necessitates the use of costly corosion resistan~
materials of construction for ~he reactor. ~urther, D-15,591 .
Backqround of_the Invention Trialkoxysilanes are used in the production of silane coupling age~ts. U.S. Patent 3,641,077 teaches the preparation of trialkoxysilanes by direct~y reacting silicon metal wi~h alcohol in ~he presence of a catalyst produced by sintering coppe~
and silicon. However, this method results in low yields of trialkoxysilanes.
Patent 3,775,457 teaches the production of alkoxysilanes from the reaction of an alcohol and finely divided silicon metal in the presence of a c~prous chloride catalyst. Although the use of cuprous chloride results in increased yield over that obtained using the sintered copper-silicon catalyst, ~che use of ~uprous chloride ca~alyst also results in the formation of HCl which in turn necessitates the use of costly corosion resistan~
materials of construction for ~he reactor. ~urther, D-15,591 .
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the pre~ence of chloride in the reactor and in the product s~ream reduces the yield of ~rialkoxysilane by catalyzing the further reaction ~f trialkoxysilane with the alcohol to yiel tetra-alkoxysilane. Alss, when methanal is a reactant, ~he HCl resulting from ~he use of the ~uprous chloride catalyst will react with ~ome of ~he methanol to produce methyl chloride and water, This ma~es the cuprous chloride-catalyzed reaction inefficient throu~h the loss of methanol and the wa~er can react with trialkoxysilanes to produce siloxanes. The presence of water in ~he reaction mixture can also inhibit the conversion of silicon metal.
Thus, there continues to exis~ the need for a process of directly reacting silicon metal and an alcohol to obtain trialkoxysilanes which process has increased yields o~ ~riakloxysilanes and yet avoids the above~mentioned deficiencies of the cuprous chloride process.
Obiects of the Invention It is th~refore an object of the inven~ion ~o provide a process ~or producing trialkoxysilane from silicon metal and alcohol which results in a high trialkoxysilane to ~etra-alkoxysilane ratio in the product.
Another object of ~he invention is to provide such a process which results in a high conversion of silicGn metal into trialkoxysilane produc~ and which r~sults in little unreacted silicon content in the reaction residue.
D-15,591 :
:132 ~3~o A further object of the invention is to provide such a process which does not reguire the use of costly corrosion resistant materials in the ~onstruction of the process apparatus.
SummarY of the Invention The present invention provides a process ~or producing trialkoxysilane of the formula HSi(0~)3 wherei~ R is an alkyl group containing from 1 to 6 carbon atoms inclusive, which process comprises:
(a) f~rming a reaction mixture ~omprising an alcohol of the formula ROH, an inert solvent, silicon metal, and a catalytically effective amount of copper (II) hydroxide; and ~ b) r~acting ~aid alcoh~l with said silicon metal to produce ~rialkoxysilane.
The process of this invention produces trialkoxysilanes in high yield with ratios of ~rialkoxysilane to te~raalkoxysilanes ~f greater th~n about 9 to 1 ~on a weight basis). Furthermorer the use of copper (II) hydroxide does not generate corrosive materials and thus costly materials of cons~ruction are not reguired fcr the reactor. The process of the inven~ion also results in high silicon conversion.
Detailed Description of the Invention Catal~t The copper (~I~ hydroxide catalyst used in the process of this invention i5 present in an ~ -~
amount effective to c~talyze the reaction.
~ 15,591 " , : . . : : .:
1 ~ 2 A ~ 3 3 Generally an effective amount ranyes from about 0.01 to about 5 par~s by weigh~ of catalys~ per 100 parts ~y weight of the silicon metal. Usually the amount of copper ~II) hydroxide will be rom about 0.1 to about 2.6 ~art by weight per 100 parts ~y of the weight ~ilicon metal. The preferred am~unt of copper (II) hydroxide catalyst is from ab~ut 0.1 to about 0.7 parts by weight per 100 par~s by weight cilicon metal.
Silicon The silicon metal reactant used in the process of this invention can generally be any commercially available grade of silicon in particula~e form. A typical composition of commercial silicon metal useful in this inven~ion, expressed in percent by weight, is Sillcon - 98 . 5%;
Iron - less than 0.50~; Aluminum - 0.20 to 0.35%;
Calcium - 0.02 to 0.10%; Water less than 0.1%;
Lead less than lOppm; Boron - less than 20ppm.
Generally smaller particle size (less than about 50 mesh~ is preferred or ease of processin~. Sieving of ground ~ilicon to regulate particle size is optional.
The presence of tin in the reaction has adverse effects on the reaction rate and/or the ~electivity for trialkoxysilane and so should be avoided (e.g. amounts as low as 75 parts per million ~how an adverse effect on the reaction).
Alcohol The al~ohols which are useful in the process of this invention are those of ~he formula D 15,591 s --~ 3 2 ~ 3 .~ ~
ROH wherein R is an alkyl group containing from 1 to 6 carbon atoms, inclusive. Preferably R is an alkyl group ~ontaining from 1 to 3 ~arbon atoms in~lusive. The most preferred alcohols are methanol and ethanol.
The silicon metal, catalyst and solvent can :.
be added together in any order. Generally, the reaction is run in a slurry and the alcohol is fed into ~he slurry as a gas or liquid. The reaction typically displays a one to two hour induction period. The initial alchohol feed ra~e is therefore low and is brought up as the reaction progresses.
Generally, once th~ reaction ig running, the alcohol ~eed rate can be adjusted to give the desired level of methanol conversion. One skilled in the art can readily adjust the feed rate in a given reaction run by moni~oring the produot composition. If the eed rate is too high the product stream will contain a larger proportion of unreacted a~cohol.
Sol~ent The solvents useful in the process of this invention are inert ~olvents ~hat do not degrade under the reaction conditions, The preferred solvents are high temperature stable organic solvents such as Therminol~ 5~, ~0 and Therminol~ 66, diphenyl ether and dodecylbenzene.
THERMINOL is the Monsanto Company trade name for heat transfer fluids. THERMINOL~ 60 is a polyaromatic compound with an average molecular weight of 250. I~ optimum temperature range is from -45 to 315C. T~ERMINOL~ 66 is a modified -~
~erpherlyl with an average molecular weight of 24 0 .
D-15, 591 :, .
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It has a higher upper temperature limit than the THERMINOL 60: its maximum upper temperature limit is 371C. The solvent i~ present in an amou~t sufficient to disper~e ~he reactants homogeneously.
Reaction Conditions The reaction is generally condu~ted at tempera~ures above about 150~ but below such a tempera~ure as would degrade or decompose the reactants or solvents. Pref~rably the reaction temperature is maintained in a range from abou~
200C to about ~40C. The reac~ion could of course be run at higher t~mperatures al~hough at no particular advantage.
The pressure at which the reaction is conducted is not critical and can be varied from subatmospheric to superatmospheric. The reaction is ~enerally run at about atmospheric pressure.
Preferably the contents of the reaction mixture are agitated to maintain a well mixed slurry of the silicon particles and alcohol in the solvent. The reac~ion mixture is preferably well insulated ~o assure ~hat the trialkoxysilane does not reflux. Refluxing could encourage further reaction of the trialkoxysilane with ~he alcohol, resulting iA loss of the desired trialkoxysilane product by the formation of tetramethoxysilane.
Recovery When methanol is the alcohol feed. ~he recovery of ~he trimetho~ysilane product ~rom the crude product is difficult since the the methanol and trimethoxysilane form a minimum boiling :
~-15,~91 azeotrope containing about 54% methanol. If the crude product is recycled to the reactor with the trimethoxysilane unremQved, the t rimethoxysilane will likely react further wi~h the methanol to produce tetramethoxysilane. It has be~n found th~t tetramethoxysilane can be used to extract the trimethoxysilane from the methanol/trimethoxysilane azeotrope. When tetramethoxysilane is added to the methanol/trimethoxysilane azeotrope in a continuous distillation operation the methanol can be distilled of while the trimethoxysilane remains behind with the tetraamethoxysilane. This distillation/recovery process uses tetramethoxysilane which is produced as a by-product of the reaction between the silicon and the alcohol to recover the desired trimethoxysilane from the azeotrope in high purity and e~ficiency.
Using tetramethoxysilane as the extractant minimizes cost and separating difficulty since no new material need be introduced into the system.
The above-describ~d extractive distilla~ion can for example be conducted in two continuous distillation columns. The f irst column serves as the extrac~i~e column, where tetramethoxysilane is added near the top of the column thus flowing downward to contact the azeotrope, thus allowing the methanol ~o be distilled off (overhead) from the trimethoxysilane and tetramethoxysilane (bottoms).
In the second column trimethoxysilane can be distilled off (overhead) from ~he tetramethoxysilane (bottoms). The tetramethoxysilane can be collected near ~he bottom of the second column and be recycled to the top of the first column.
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- 8 ~ 3 Whereas the scope of the instant invention is set forth in the appended claims, the following ~pecific examples are set forth for illustration only and are not to be construed as limiting the scope of the invention.
D-15,591 9 :~ 3 .~
EXAMP~S
A lD00 milliliter four neck flask was charged wi~h 50 grams of silicon metal, 100 cc of THERMINOL~ 60, a high boiling inert solv2nt, and copper (II) hydroxide catalyst. Alcohol was added either via a gravity feed ~onstan~ addition funnel or through an FMI~ pump and ~low was controlled using a micrometer adjustment. The reaction temperature was controlled using a thermometer and an I2R~ Th~rmo-O-Watch. The reactants were agitated using ~ mechanical stirrer, i~e. an air motor, with a teflon blade and glass shaft. A
short ~about 12") Vi~reux column was used ~o stop entrainment of the solvent. Product samples were .
removed at time interval~ through a distilla~ion head with a nitro~en blow-by and collec~ed in a 250 milliliter receiver. The product cuts or samples were taken on a 0.5-2 hour basis and 2 to 5 gram samples were submitted in pre sure bottles for gas ~hromatographic analysis. The reaction was run at 220C until no more silicon metal was conver~ed to volatile products.
: TABLES
The Table numbers correspond to Example numbers.
The column headin~s in the following tables have the fol lowing meanings:
SAMPLE TAKEN Weight of the Sample collected in grams D-lS,591 -- 10 -- ~L 3 1~ A r~ ~ ~
~X TI~ React i on t ime interval s ince previous sample ~minutes) METHANOL FEED(GM) ~eight of ~he methanol fed between samples (grams~
MEOH ~eight % me~hanol in sample determin~d by gas chromatograph analy~is TRI Weight % trialkoxysilane product in sampl~ determined by gas chromatograph analysis TETR Weight % te~ramethoxysilane by gas chromatograph analysis SILOXANES Weight ~ to~al di-siloxane compounds (Tetra-Te~ra, Tri-Tri and Tetra-Tri) ~OL Weight ~ Solvent in sample determined by gas chromatograph analysis The data shown under ~he above 1 isted colulTn headings were used to calculate the entries under the below listed column headings.
ET~ANOL R~TE (GM/~) Methanol ~eed rate (grams/hour).
Si IN POT ~M~ Unreacted silicon metal remaining in the pot bef ore each ~ample (gram~).
Si/SAMPLE TOTAL (GM~ Total silicon present in each sample (grams 3 .
i~SAMPLE RATE (GM/H~ Rate of silicon production in each sample ~grams/hour).
ELECTI~ITY/SAMPLE Selectivity for each sample (ratio of trimethoxysilane to te~rametho~ysilane (by we i ght ) ) .
-15,591 `
S~LECTIVITY/CUM Cumulative electivi~y after each sample. (Ratio of trimethoxysilane to tetramethoxysilane produced from be~inning of reaction to time of ~ample) :
Example l In this example 1.3 grams of copper (II) hydroxide catalyst was employed, ~he silicon metal was 65 x 150 mesh particles.
An air motor provided agitation of the reactants. Samples were taken at ~ime in~ervals as shown. As can be seen rom the da~a on Table I, below the ra~io of Srimethoxysilane to tetrame~hoxysilane produced is good, approximately 7 to 1.
This represents an 80.4 mol0 percent conversion of the silicon metal to trimethoxysilane. In contrast, only 10 mole percent of the silicon metal was converted to tetramethoxysilane.
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Exam~es ~ Throuqh 5 Examples 2 through 5 were run in the manner described for Example 1 exc~pt that the amount of copper (II) hydroxide catalyst was varied as ~hown, below. Exampl~s 3, ~ and 5 demonstrate that ~he ~olvent can be reused in ~ubsequent runs of the process.
Exam~e 2 In thi~ example 0.65 grams of copper ~II) hydroxide was ~mployed, the ~ilicon metal was 65x150 mesh particles. hn air motor provided agitation of the reactants.
This run showed an 82.6 mole percent conversion of the silicon metal to trimethoxysilane. In contrast, only 9.3 mole percent of the silicon metal was ~onverted to tetramethoxysilane.
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- 15 - ~2~3~3 ExamP-le 3 In this exampl~, 0.65 grams of copper (II) hydroxide was employed, the silicon metal was 65~150 mesh particles. Solvent from a previous experiment w~s recycl~d, (77.5 grams) and ~.5 grams of unused solvent was added to give 100 grams of ~olven~.
This run showed an 82.9 mole percent conversion of the silicon metal to trimethoxysilane. In contrast, only 9.4 mole percent of the silieon metal was converted to tetramethoxysilane.
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Example 4 In this example 0.33 grams of copper (II) hydroxide was employed. The silicon metal was 6~x150 mesh particles. Solvent ~rom a previous experiment was rerycled (7~.5 grm~ nd 22.2 grams of unused solvent was added to gi~e 100 grams of solvent.
~ his run showed an 83.9 mole percen~
conversion of silicon metal to trimethoxysilane. In contra~t, only 5.9 mole percent of the ~ilicon metal was converted ~o tetramethoxys~lane.
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Example 5 In ~his example 0.11 grams of copper (II) hydroxide was employed. The ~ilicon metal was 65x150 me~h particl~s. Solvent from a prPvious experimen~ was recycled (82.0 grams), and 18.0 grams of unused solvent wa~ added to give 100 grams of solvent. This run showed an B9.1 mole percent conversion of the silicon metal to trimethoxysilane. In contrast only 4.4 mole percent ~ilicon metal was converted to tetramethoxysilane.
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- 21 ~ 3 ~ le~ ~ ~d 7 Examples 6 and 7 demonstrate that silicon and copper (II) hydroxide can be added to the reaction zone to replace consumed startinq material.
xample 6 In this experiment 0.33 grams o~ ~opper (II) hydroxide was employed. The silicon metal was 65x150 mesh particles. The initial amount of silicon metal was 50 grams.
Three additions, each containing 20 grams of silicon and 0.13 grams of copper (II) hydroxide were made to the slurry a~ter samples 6q, ~i and 6k were taken, as indicated by an as~erisk on Table 6, below.
This run showed an 82.6 mole percent conversion of silicon metal to trimethoxysila~e. In contrast only 9.3 mole percent silicon metal was converted to tetramethoxysilane.
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:~2:~3~J3 Example 7 In this experiment 0.33 grams of copper tII) hydroxide was employed. The silicon metal was 65x150 me~h par~icles. The initial amoun~ of silicon metal was 50 grams. Three additions, ~ach containing 20 grams of silicon metal and 0.13 grams of copper (II) hydroxide were made to the slurry after sample 7d, 7h and 7k, as indica~ed by an asterisk in Table 7, below.
This run showed an B0.4 mole peroent conversion of silicon metal to trimethoxysilane. In contrast only 9.6 mole percent silicon metal was converted to tetramethoxysilane.
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the pre~ence of chloride in the reactor and in the product s~ream reduces the yield of ~rialkoxysilane by catalyzing the further reaction ~f trialkoxysilane with the alcohol to yiel tetra-alkoxysilane. Alss, when methanal is a reactant, ~he HCl resulting from ~he use of the ~uprous chloride catalyst will react with ~ome of ~he methanol to produce methyl chloride and water, This ma~es the cuprous chloride-catalyzed reaction inefficient throu~h the loss of methanol and the wa~er can react with trialkoxysilanes to produce siloxanes. The presence of water in ~he reaction mixture can also inhibit the conversion of silicon metal.
Thus, there continues to exis~ the need for a process of directly reacting silicon metal and an alcohol to obtain trialkoxysilanes which process has increased yields o~ ~riakloxysilanes and yet avoids the above~mentioned deficiencies of the cuprous chloride process.
Obiects of the Invention It is th~refore an object of the inven~ion ~o provide a process ~or producing trialkoxysilane from silicon metal and alcohol which results in a high trialkoxysilane to ~etra-alkoxysilane ratio in the product.
Another object of ~he invention is to provide such a process which results in a high conversion of silicGn metal into trialkoxysilane produc~ and which r~sults in little unreacted silicon content in the reaction residue.
D-15,591 :
:132 ~3~o A further object of the invention is to provide such a process which does not reguire the use of costly corrosion resistant materials in the ~onstruction of the process apparatus.
SummarY of the Invention The present invention provides a process ~or producing trialkoxysilane of the formula HSi(0~)3 wherei~ R is an alkyl group containing from 1 to 6 carbon atoms inclusive, which process comprises:
(a) f~rming a reaction mixture ~omprising an alcohol of the formula ROH, an inert solvent, silicon metal, and a catalytically effective amount of copper (II) hydroxide; and ~ b) r~acting ~aid alcoh~l with said silicon metal to produce ~rialkoxysilane.
The process of this invention produces trialkoxysilanes in high yield with ratios of ~rialkoxysilane to te~raalkoxysilanes ~f greater th~n about 9 to 1 ~on a weight basis). Furthermorer the use of copper (II) hydroxide does not generate corrosive materials and thus costly materials of cons~ruction are not reguired fcr the reactor. The process of the inven~ion also results in high silicon conversion.
Detailed Description of the Invention Catal~t The copper (~I~ hydroxide catalyst used in the process of this invention i5 present in an ~ -~
amount effective to c~talyze the reaction.
~ 15,591 " , : . . : : .:
1 ~ 2 A ~ 3 3 Generally an effective amount ranyes from about 0.01 to about 5 par~s by weigh~ of catalys~ per 100 parts ~y weight of the silicon metal. Usually the amount of copper ~II) hydroxide will be rom about 0.1 to about 2.6 ~art by weight per 100 parts ~y of the weight ~ilicon metal. The preferred am~unt of copper (II) hydroxide catalyst is from ab~ut 0.1 to about 0.7 parts by weight per 100 par~s by weight cilicon metal.
Silicon The silicon metal reactant used in the process of this invention can generally be any commercially available grade of silicon in particula~e form. A typical composition of commercial silicon metal useful in this inven~ion, expressed in percent by weight, is Sillcon - 98 . 5%;
Iron - less than 0.50~; Aluminum - 0.20 to 0.35%;
Calcium - 0.02 to 0.10%; Water less than 0.1%;
Lead less than lOppm; Boron - less than 20ppm.
Generally smaller particle size (less than about 50 mesh~ is preferred or ease of processin~. Sieving of ground ~ilicon to regulate particle size is optional.
The presence of tin in the reaction has adverse effects on the reaction rate and/or the ~electivity for trialkoxysilane and so should be avoided (e.g. amounts as low as 75 parts per million ~how an adverse effect on the reaction).
Alcohol The al~ohols which are useful in the process of this invention are those of ~he formula D 15,591 s --~ 3 2 ~ 3 .~ ~
ROH wherein R is an alkyl group containing from 1 to 6 carbon atoms, inclusive. Preferably R is an alkyl group ~ontaining from 1 to 3 ~arbon atoms in~lusive. The most preferred alcohols are methanol and ethanol.
The silicon metal, catalyst and solvent can :.
be added together in any order. Generally, the reaction is run in a slurry and the alcohol is fed into ~he slurry as a gas or liquid. The reaction typically displays a one to two hour induction period. The initial alchohol feed ra~e is therefore low and is brought up as the reaction progresses.
Generally, once th~ reaction ig running, the alcohol ~eed rate can be adjusted to give the desired level of methanol conversion. One skilled in the art can readily adjust the feed rate in a given reaction run by moni~oring the produot composition. If the eed rate is too high the product stream will contain a larger proportion of unreacted a~cohol.
Sol~ent The solvents useful in the process of this invention are inert ~olvents ~hat do not degrade under the reaction conditions, The preferred solvents are high temperature stable organic solvents such as Therminol~ 5~, ~0 and Therminol~ 66, diphenyl ether and dodecylbenzene.
THERMINOL is the Monsanto Company trade name for heat transfer fluids. THERMINOL~ 60 is a polyaromatic compound with an average molecular weight of 250. I~ optimum temperature range is from -45 to 315C. T~ERMINOL~ 66 is a modified -~
~erpherlyl with an average molecular weight of 24 0 .
D-15, 591 :, .
- , 3 2 ~
It has a higher upper temperature limit than the THERMINOL 60: its maximum upper temperature limit is 371C. The solvent i~ present in an amou~t sufficient to disper~e ~he reactants homogeneously.
Reaction Conditions The reaction is generally condu~ted at tempera~ures above about 150~ but below such a tempera~ure as would degrade or decompose the reactants or solvents. Pref~rably the reaction temperature is maintained in a range from abou~
200C to about ~40C. The reac~ion could of course be run at higher t~mperatures al~hough at no particular advantage.
The pressure at which the reaction is conducted is not critical and can be varied from subatmospheric to superatmospheric. The reaction is ~enerally run at about atmospheric pressure.
Preferably the contents of the reaction mixture are agitated to maintain a well mixed slurry of the silicon particles and alcohol in the solvent. The reac~ion mixture is preferably well insulated ~o assure ~hat the trialkoxysilane does not reflux. Refluxing could encourage further reaction of the trialkoxysilane with ~he alcohol, resulting iA loss of the desired trialkoxysilane product by the formation of tetramethoxysilane.
Recovery When methanol is the alcohol feed. ~he recovery of ~he trimetho~ysilane product ~rom the crude product is difficult since the the methanol and trimethoxysilane form a minimum boiling :
~-15,~91 azeotrope containing about 54% methanol. If the crude product is recycled to the reactor with the trimethoxysilane unremQved, the t rimethoxysilane will likely react further wi~h the methanol to produce tetramethoxysilane. It has be~n found th~t tetramethoxysilane can be used to extract the trimethoxysilane from the methanol/trimethoxysilane azeotrope. When tetramethoxysilane is added to the methanol/trimethoxysilane azeotrope in a continuous distillation operation the methanol can be distilled of while the trimethoxysilane remains behind with the tetraamethoxysilane. This distillation/recovery process uses tetramethoxysilane which is produced as a by-product of the reaction between the silicon and the alcohol to recover the desired trimethoxysilane from the azeotrope in high purity and e~ficiency.
Using tetramethoxysilane as the extractant minimizes cost and separating difficulty since no new material need be introduced into the system.
The above-describ~d extractive distilla~ion can for example be conducted in two continuous distillation columns. The f irst column serves as the extrac~i~e column, where tetramethoxysilane is added near the top of the column thus flowing downward to contact the azeotrope, thus allowing the methanol ~o be distilled off (overhead) from the trimethoxysilane and tetramethoxysilane (bottoms).
In the second column trimethoxysilane can be distilled off (overhead) from ~he tetramethoxysilane (bottoms). The tetramethoxysilane can be collected near ~he bottom of the second column and be recycled to the top of the first column.
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- 8 ~ 3 Whereas the scope of the instant invention is set forth in the appended claims, the following ~pecific examples are set forth for illustration only and are not to be construed as limiting the scope of the invention.
D-15,591 9 :~ 3 .~
EXAMP~S
A lD00 milliliter four neck flask was charged wi~h 50 grams of silicon metal, 100 cc of THERMINOL~ 60, a high boiling inert solv2nt, and copper (II) hydroxide catalyst. Alcohol was added either via a gravity feed ~onstan~ addition funnel or through an FMI~ pump and ~low was controlled using a micrometer adjustment. The reaction temperature was controlled using a thermometer and an I2R~ Th~rmo-O-Watch. The reactants were agitated using ~ mechanical stirrer, i~e. an air motor, with a teflon blade and glass shaft. A
short ~about 12") Vi~reux column was used ~o stop entrainment of the solvent. Product samples were .
removed at time interval~ through a distilla~ion head with a nitro~en blow-by and collec~ed in a 250 milliliter receiver. The product cuts or samples were taken on a 0.5-2 hour basis and 2 to 5 gram samples were submitted in pre sure bottles for gas ~hromatographic analysis. The reaction was run at 220C until no more silicon metal was conver~ed to volatile products.
: TABLES
The Table numbers correspond to Example numbers.
The column headin~s in the following tables have the fol lowing meanings:
SAMPLE TAKEN Weight of the Sample collected in grams D-lS,591 -- 10 -- ~L 3 1~ A r~ ~ ~
~X TI~ React i on t ime interval s ince previous sample ~minutes) METHANOL FEED(GM) ~eight of ~he methanol fed between samples (grams~
MEOH ~eight % me~hanol in sample determin~d by gas chromatograph analy~is TRI Weight % trialkoxysilane product in sampl~ determined by gas chromatograph analysis TETR Weight % te~ramethoxysilane by gas chromatograph analysis SILOXANES Weight ~ to~al di-siloxane compounds (Tetra-Te~ra, Tri-Tri and Tetra-Tri) ~OL Weight ~ Solvent in sample determined by gas chromatograph analysis The data shown under ~he above 1 isted colulTn headings were used to calculate the entries under the below listed column headings.
ET~ANOL R~TE (GM/~) Methanol ~eed rate (grams/hour).
Si IN POT ~M~ Unreacted silicon metal remaining in the pot bef ore each ~ample (gram~).
Si/SAMPLE TOTAL (GM~ Total silicon present in each sample (grams 3 .
i~SAMPLE RATE (GM/H~ Rate of silicon production in each sample ~grams/hour).
ELECTI~ITY/SAMPLE Selectivity for each sample (ratio of trimethoxysilane to te~rametho~ysilane (by we i ght ) ) .
-15,591 `
S~LECTIVITY/CUM Cumulative electivi~y after each sample. (Ratio of trimethoxysilane to tetramethoxysilane produced from be~inning of reaction to time of ~ample) :
Example l In this example 1.3 grams of copper (II) hydroxide catalyst was employed, ~he silicon metal was 65 x 150 mesh particles.
An air motor provided agitation of the reactants. Samples were taken at ~ime in~ervals as shown. As can be seen rom the da~a on Table I, below the ra~io of Srimethoxysilane to tetrame~hoxysilane produced is good, approximately 7 to 1.
This represents an 80.4 mol0 percent conversion of the silicon metal to trimethoxysilane. In contrast, only 10 mole percent of the silicon metal was converted to tetramethoxysilane.
.
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Exam~es ~ Throuqh 5 Examples 2 through 5 were run in the manner described for Example 1 exc~pt that the amount of copper (II) hydroxide catalyst was varied as ~hown, below. Exampl~s 3, ~ and 5 demonstrate that ~he ~olvent can be reused in ~ubsequent runs of the process.
Exam~e 2 In thi~ example 0.65 grams of copper ~II) hydroxide was ~mployed, the ~ilicon metal was 65x150 mesh particles. hn air motor provided agitation of the reactants.
This run showed an 82.6 mole percent conversion of the silicon metal to trimethoxysilane. In contrast, only 9.3 mole percent of the silicon metal was ~onverted to tetramethoxysilane.
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- 15 - ~2~3~3 ExamP-le 3 In this exampl~, 0.65 grams of copper (II) hydroxide was employed, the silicon metal was 65~150 mesh particles. Solvent from a previous experiment w~s recycl~d, (77.5 grams) and ~.5 grams of unused solvent was added to give 100 grams of ~olven~.
This run showed an 82.9 mole percent conversion of the silicon metal to trimethoxysilane. In contrast, only 9.4 mole percent of the silieon metal was converted to tetramethoxysilane.
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Example 4 In this example 0.33 grams of copper (II) hydroxide was employed. The silicon metal was 6~x150 mesh particles. Solvent ~rom a previous experiment was rerycled (7~.5 grm~ nd 22.2 grams of unused solvent was added to gi~e 100 grams of solvent.
~ his run showed an 83.9 mole percen~
conversion of silicon metal to trimethoxysilane. In contra~t, only 5.9 mole percent of the ~ilicon metal was converted ~o tetramethoxys~lane.
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Example 5 In ~his example 0.11 grams of copper (II) hydroxide was employed. The ~ilicon metal was 65x150 me~h particl~s. Solvent from a prPvious experimen~ was recycled (82.0 grams), and 18.0 grams of unused solvent wa~ added to give 100 grams of solvent. This run showed an B9.1 mole percent conversion of the silicon metal to trimethoxysilane. In contrast only 4.4 mole percent ~ilicon metal was converted to tetramethoxysilane.
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- 21 ~ 3 ~ le~ ~ ~d 7 Examples 6 and 7 demonstrate that silicon and copper (II) hydroxide can be added to the reaction zone to replace consumed startinq material.
xample 6 In this experiment 0.33 grams o~ ~opper (II) hydroxide was employed. The silicon metal was 65x150 mesh particles. The initial amount of silicon metal was 50 grams.
Three additions, each containing 20 grams of silicon and 0.13 grams of copper (II) hydroxide were made to the slurry a~ter samples 6q, ~i and 6k were taken, as indicated by an as~erisk on Table 6, below.
This run showed an 82.6 mole percent conversion of silicon metal to trimethoxysila~e. In contrast only 9.3 mole percent silicon metal was converted to tetramethoxysilane.
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:~2:~3~J3 Example 7 In this experiment 0.33 grams of copper tII) hydroxide was employed. The silicon metal was 65x150 me~h par~icles. The initial amoun~ of silicon metal was 50 grams. Three additions, ~ach containing 20 grams of silicon metal and 0.13 grams of copper (II) hydroxide were made to the slurry after sample 7d, 7h and 7k, as indica~ed by an asterisk in Table 7, below.
This run showed an B0.4 mole peroent conversion of silicon metal to trimethoxysilane. In contrast only 9.6 mole percent silicon metal was converted to tetramethoxysilane.
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Claims (19)
1. A process for producing trialkoxysilane of the formula HSi(OR)3 wherein R is an alkyl group containing from 1 to 6 carbon atoms which comprises:
(a) forming a reaction mixture comprising an alcohol of the formula ROH wherein R
is as defined above, an inert solvent wherein said solvent is a high temperature stable organic aromatic hydrocarbon or aromatic ether, silicon metal, and a catalytically effective amount of copper (II) hydroxide; and (b) reacting said alcohol with said silicon metal in the presence of said copper (II) hydroxide to produce the trialkoxysilane.
(a) forming a reaction mixture comprising an alcohol of the formula ROH wherein R
is as defined above, an inert solvent wherein said solvent is a high temperature stable organic aromatic hydrocarbon or aromatic ether, silicon metal, and a catalytically effective amount of copper (II) hydroxide; and (b) reacting said alcohol with said silicon metal in the presence of said copper (II) hydroxide to produce the trialkoxysilane.
2. The process of claim 1, wherein R is an alkyl group containing from 1 to 3 carbon atoms.
3. The process of claim 2 wherein R is methyl.
4. The process of claim 2 wherein R is ethyl.
5. The process of claim 1 wherein the amount of copper (II) hydroxide catalyst is from about 0.01 to about 5 parts by weight per 100 parts by weight of silicon metal.
6. The process of claim 1 wherein the amount of copper (II) hydroxide is from about 0.1 to about 2.6 parts by weight per 100 parts by weight of silicon metal.
7. The process of claim 1 wherein the amount of copper (II) hydroxide is from about 0.1 to about 0.7 parts by weight per 100 parts by weight of silicon metal.
8. The process of claim 1 wherein the reaction mixture is agitated during the reaction.
9. The process of claim 1 wherein the temperature is maintained above about 150°C during the reaction.
10. The process of claim 9, wherein the temperature is maintained in the range of about 200°C to about 240°C.
11. The process of claim 1 wherein additional amounts of silicon metal are subsequently fed to the reaction to replace silicon metal consumed.
12. A process for producing trimethoxysilane, HSi(OCH3)3, which comprises:
(a) forming a reaction mixture comprising methanol, an inert solvent wherein said solvent is a high temperature stable organic aromatic hydrocarbon or aromatic ether, silicon metal and a catalytically effective amount of copper (II) hydroxide; and (b) reacting said methanol with said silicon metal in the presence of the copper (II) hydroxide to produce trimethoxysilane.
(a) forming a reaction mixture comprising methanol, an inert solvent wherein said solvent is a high temperature stable organic aromatic hydrocarbon or aromatic ether, silicon metal and a catalytically effective amount of copper (II) hydroxide; and (b) reacting said methanol with said silicon metal in the presence of the copper (II) hydroxide to produce trimethoxysilane.
13. The process of claim 12 wherein the amount of copper (II) hydroxide catalyst is from about 0.01 to about 5 parts by weight per 100 parts by weight of silicon metal.
14. The process of claim 13 wherein the amount of copper (II) hydroxide is from about 0.1 to about 2.6 parts by weight per 100 parts by weight of silicon metal.
15. The process of claim 14 wherein the amount of copper (II) hydroxide is from about 0.1 to about 0.7 parts by weight per 100 parts by weight of silicon metal.
16. The process of claim 12 wherein the reaction mixture is agitated during step (b).
17. The process of claim 12 wherein the temperature of the reaction zone is maintained above about 150°C during step (b).
18. The process of claim 17 wherein the temperature of the reaction zone is maintained in the range of about 200°C to about 240°C.
19. The process of claim 18, wherein additional amounts of silicon metal are added to the reaction zone to replace silicon metal consumed by the reaction.
D-15,591
D-15,591
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US033,017 | 1987-03-31 | ||
| US07/033,017 US4727173A (en) | 1987-03-31 | 1987-03-31 | Process for producing trialkoxysilanes from the reaction of silicon metal and alcohol |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1321398C true CA1321398C (en) | 1993-08-17 |
Family
ID=21868110
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000562936A Expired - Fee Related CA1321398C (en) | 1987-03-31 | 1988-03-30 | Process for producing trialkoxysilanes from the reaction of silicon metal and alcohol |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4727173A (en) |
| EP (1) | EP0285133B1 (en) |
| JP (1) | JPH0717656B2 (en) |
| AT (1) | ATE70843T1 (en) |
| BR (1) | BR8801506A (en) |
| CA (1) | CA1321398C (en) |
| DE (1) | DE3867104D1 (en) |
| MX (1) | MX169077B (en) |
Families Citing this family (29)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1323037C (en) * | 1987-02-23 | 1993-10-12 | Yoshiro Ohta | Process for the production of trialkoxysilanes |
| US4761492A (en) * | 1987-09-28 | 1988-08-02 | Union Carbide Corporation | Process for recovering trimethoxysilane from a trimethoxysilane and methanol mixture |
| US4999446A (en) * | 1990-06-21 | 1991-03-12 | Union Carbide Chemicals And Plastics Company Inc. | Trimethoxysilane preparation via the methanol-silicon reaction with recycle |
| US5041595A (en) * | 1990-09-26 | 1991-08-20 | Union Carbide Chemicals And Plastics Technology Corporation | Method for manufacturing vinylalkoxysilanes |
| US5177234A (en) * | 1991-06-03 | 1993-01-05 | Dow Corning Corporation | Preparation of alkoxysilanes by contacting a solution of hydrogen fluoride in an alcohol with silicon |
| US5084590A (en) * | 1991-06-24 | 1992-01-28 | Union Carbide Chemicals & Plastics Technology Corporation | Trimethoxysilane preparation via the methanol-silicon reaction using a continuous process and multiple reactors |
| US5166384A (en) * | 1992-04-07 | 1992-11-24 | Union Carbide Chemicals & Plastics Technology Corporation | Method for the removal of siloxane dissolved in the solvent employed in the preparation of trimethoxysilane via methanol-silicon metal reaction |
| US5783720A (en) | 1996-10-10 | 1998-07-21 | Osi Specialties, Inc. | Surface-active additives in the direct synthesis of trialkoxysilanes |
| US6090965A (en) * | 1998-04-02 | 2000-07-18 | Osi Specialties, Inc. | Removal of dissolved silicates from alcohol-silicon direct synthesis solvents |
| DE10025367A1 (en) * | 2000-05-23 | 2001-12-13 | Basf Ag | Freshly precipitated CuO as a catalyst for trialkoxysilane synthesis |
| DE10033964A1 (en) | 2000-07-13 | 2002-01-24 | Basf Ag | Fluorinated copper salts as a catalyst for trialkoxysilane synthesis |
| US7858818B2 (en) * | 2001-01-31 | 2010-12-28 | Momentive Performance Materials Inc. | Nanosized copper catalyst precursors for the direct synthesis of trialkoxysilanes |
| US7339068B2 (en) | 2001-01-31 | 2008-03-04 | Momentive Performance Materials Inc. | Nanosized copper catalyst precursors for the direct synthesis of trialkoxysilanes |
| DE10116007A1 (en) | 2001-03-30 | 2002-10-02 | Degussa | Device and method for producing essentially halogen-free trialkoxysilanes |
| US6580000B1 (en) | 2002-06-06 | 2003-06-17 | Ak Research Company | Process for the manufacture of alkoxysilanes and alkoxy orthosilicates |
| US7652164B2 (en) * | 2005-09-13 | 2010-01-26 | Momentive Performance Materials Inc. | Process for the direct synthesis of trialkoxysilane |
| US7365220B2 (en) * | 2005-09-29 | 2008-04-29 | Momentive Performance Materials Inc. | Process for the recovery of alkoxysilanes obtained from the direct reaction of silicon with alkanols |
| US7645894B2 (en) * | 2006-04-22 | 2010-01-12 | Bernard Kanner | Direct process for making cyclic dimethylsiloxane oligomers |
| US7429672B2 (en) | 2006-06-09 | 2008-09-30 | Momentive Performance Materials Inc. | Process for the direct synthesis of trialkoxysilane |
| MX2009005369A (en) * | 2006-12-01 | 2009-10-13 | Roston Family Llc | Process for preparation of alkoxys i lan es. |
| US8153566B2 (en) | 2008-09-30 | 2012-04-10 | Cherron Oronite Company LLC | Lubricating oil compositions |
| US8197782B2 (en) | 2010-02-08 | 2012-06-12 | Momentive Performance Materials | Method for making high purity metal oxide particles and materials made thereof |
| US8901050B2 (en) | 2010-03-31 | 2014-12-02 | Chevron Oronite Company Llc | Method for improving copper corrosion performance |
| US8933001B2 (en) | 2010-03-31 | 2015-01-13 | Chevron Oronite Company Llc | Method for improving fluorocarbon elastomer seal compatibility |
| JP6401612B2 (en) | 2011-07-29 | 2018-10-10 | モーメンティブ・パフォーマンス・マテリアルズ・インク | Method for producing high-purity metal oxide particles and material produced therefor |
| KR101422080B1 (en) | 2011-09-06 | 2014-07-22 | 인스티튜트 오브 아이온-플라즈마엔드 레이저 테크놀러지스 | A method for preparing trialkoxysilane |
| US9556208B2 (en) | 2012-10-12 | 2017-01-31 | Momentive Performance Materials Inc. | Hydrosilylation synthesis of haloalkylorganosilanes using peroxide promoters |
| DE102019122174A1 (en) | 2019-08-19 | 2021-02-25 | Voco Gmbh | Dental polymerizable composition based on condensed silanes |
| CN113797568B (en) * | 2021-08-20 | 2022-12-23 | 洛阳中硅高科技有限公司 | Synthesis device and synthesis method of electronic grade tri (dimethylamino) silane |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2473260A (en) * | 1946-06-26 | 1949-06-14 | Gen Electric | Preparation of tetramethyl silicate |
| US3072700A (en) * | 1959-08-07 | 1963-01-08 | Union Carbide Corp | Process for producing silanes |
| DE1298972B (en) * | 1967-09-06 | 1969-07-10 | Degussa | Process for the preparation of methoxy- and AEthoxysilanes |
| US3641077A (en) * | 1970-09-01 | 1972-02-08 | Eugene G Rochow | Method for preparing alkoxy derivatives of silicon germanium tin thallium and arsenic |
| BE789535A (en) * | 1971-09-30 | 1973-01-15 | Tokyo Shibaura Electric Co | ALKOXYSILANES MANUFACTURING PROCESS |
| US3775547A (en) * | 1972-10-12 | 1973-11-27 | Westinghouse Electric Corp | Cast epoxy bushing having a weldable flange |
| US4185029A (en) * | 1975-07-19 | 1980-01-22 | Dynamit Nobel Aktiengesellschaft | Method of preparing orthosilicic acid alkyl esters |
| JPS54163529A (en) * | 1978-06-13 | 1979-12-26 | Mitsubishi Chem Ind | Production of alkoxysilane |
| JPS552641A (en) * | 1978-06-21 | 1980-01-10 | Mitsubishi Chem Ind Ltd | Preparation of alkoxysilane |
| JPS5511538A (en) * | 1978-07-11 | 1980-01-26 | Mitsubishi Chem Ind Ltd | Production of methoxysilane |
| JPS5528928A (en) * | 1978-08-21 | 1980-02-29 | Mitsubishi Chem Ind Ltd | Preparation of methoxysilane |
| JPS5528929A (en) * | 1978-08-21 | 1980-02-29 | Mitsubishi Chem Ind Ltd | Preparation of ethoxysilane |
| JPS5533457A (en) * | 1978-09-01 | 1980-03-08 | Mitsubishi Chem Ind Ltd | Preparation of trialkoxysilane |
| JPS5572197A (en) * | 1978-11-27 | 1980-05-30 | Mitsubishi Chem Ind Ltd | Stabilization of trimethoxysilane |
| JPS5572198A (en) * | 1978-11-27 | 1980-05-30 | Mitsubishi Chem Ind Ltd | Stabilization of trimethoxysilane |
| JPS5616492A (en) * | 1979-07-20 | 1981-02-17 | Mitsubishi Chem Ind Ltd | Preparation of tetraalkoxysilane |
| US4289889A (en) * | 1980-06-30 | 1981-09-15 | Union Carbide Corporation | Preparation of tetraalkoxysilanes |
| JPS5799593A (en) * | 1980-12-13 | 1982-06-21 | Kanegafuchi Chem Ind Co Ltd | Preparation of alkoxysilane |
| US4447632A (en) * | 1983-04-18 | 1984-05-08 | Union Carbide Corporation | Process for production of alkyl silicates from silicon metal |
| US4487949A (en) * | 1983-11-22 | 1984-12-11 | Union Carbide Corporation | Process for the preparation of alkyl silicates |
-
1987
- 1987-03-31 US US07/033,017 patent/US4727173A/en not_active Expired - Lifetime
-
1988
- 1988-03-30 JP JP63074897A patent/JPH0717656B2/en not_active Expired - Lifetime
- 1988-03-30 AT AT88105181T patent/ATE70843T1/en not_active IP Right Cessation
- 1988-03-30 CA CA000562936A patent/CA1321398C/en not_active Expired - Fee Related
- 1988-03-30 EP EP88105181A patent/EP0285133B1/en not_active Expired - Lifetime
- 1988-03-30 BR BR8801506A patent/BR8801506A/en not_active IP Right Cessation
- 1988-03-30 MX MX010974A patent/MX169077B/en unknown
- 1988-03-30 DE DE8888105181T patent/DE3867104D1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| MX169077B (en) | 1993-06-21 |
| ATE70843T1 (en) | 1992-01-15 |
| EP0285133B1 (en) | 1991-12-27 |
| BR8801506A (en) | 1988-11-08 |
| DE3867104D1 (en) | 1992-02-06 |
| US4727173A (en) | 1988-02-23 |
| JPS63258481A (en) | 1988-10-25 |
| JPH0717656B2 (en) | 1995-03-01 |
| EP0285133A2 (en) | 1988-10-05 |
| EP0285133A3 (en) | 1989-09-20 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |