JPH02237601A - Method for removing chlorine in alkoxysilane - Google Patents

Abstract

PURPOSE:To inexpensively and efficiently remove chlorine in alkoxysilanes with a convenient method by bringing a basic anion-exchange resin into contact with the chlorine-contg. alkoxysilanes. CONSTITUTION:The chlorine-contg. alkoxysilanes expressed by formula I (R is a 1-8C org. group and n is an integer of 0-3) are brought into contact with a basic anion-exchange resin. The alkoxysilanes are ordinarily passed through a column packed with a basic anion-exchange resin. A fixed-bed system or a moving-bed system is used in the column in this case to remove chlorine, and the desired refined compd. is obtained. The resin is preferably obtained by bonding a quaternary ammonium salt or primary to tertiary amines as an exchange group to a three-dimensionally condensation-polymerized polymer base. By this method, the chlorine content in the alkoxysilanes can be reduced in one stage without a loss of the alkoxysilanes due to their disproportionation.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for removing chlorine in alkoxysilane,
More specifically, chlorine-containing alkoxysilane,
This invention relates to a method for removing chlorine from an alkoxysilane by bringing it into contact with a basic anion exchange resin.

Technical background of the invention and its problems The following methods are known as industrial methods for producing alkoxysilanes.

(1) Reacting chlorosilanes and alcohols,
A method of producing alkoxysilane.

H S i B + (4-n) ROH -n
4-n H St(OR)4-n + (4-n)HC#n (n is an integer of O to 3) (2) Metal silicon and alcohol in the presence of a copper-based catalyst such as copper chloride A method of producing alkoxysilane through reaction.

In other words, the alkoxysilane produced by the above production method (1) contains impurities caused by hydrolyzable chlorine such as by-produced hydrogen chloride and unreacted chlorosilane, and the mixture of alcohols and hydrogen chloride. It contains impurities caused by non-hydrolyzable chlorine, such as alkyl chloride, which is a reaction product. Also, in the alkoxysilane produced by the above production method (2), hydrogen chloride, which is a hydrolysis product of copper chloride, as well as alcohols and hydrogen chloride, are contained, as in the alkoxysilane produced by the production method (1). Contains alkyl chloride, which is a reaction product with

Such alkoxysilane is a useful compound used as a silane coupling agent or as a raw material for synthetic quartz, etc. However, if the raw material alkoxysilane contains impurities caused by the above chlorine, electrical and electronic Final products such as those in the field also contain impurities caused by silica,
Therefore, the insulation properties of the products deteriorate, making it difficult to apply these products to the electrical and electronic fields.

Therefore, there is a strong desire for a method that can inexpensively and efficiently remove chlorine from alkoxysilanes.

By the way, the following methods have been disclosed as methods for removing chlorine from alkoxysilanes.

(b) When producing alkoxysilane by reacting chlorosilanes and alcohols, the reaction is carried out in the presence of basic compounds such as pyridine, anilines, amines, ammonia or sodium alcoholate, and the chloride produced How to remove hydrogen (Organosilicon Compounds)
ds) pp. 288-293, 1960, Butt
erworths Publ1catlons Llm
ited).

(Note) Method for removing chlorine impurities in methyltrimethoxysilane using metallic sodium (Journal of
Organometallic Chemistry (J.Organ
oa+etal. Chem. ). ．． Volume 265, 19
1984, pp. 135-139).

(c) When removing chlorine impurities in alkoxysilanes, the steps of heat treating the alkoxysilanes in the presence of acid clay or metal halides, neutralizing them with a neutralizing agent, and removing neutralized salts are carried out. For example, a method for purifying alkoxysilane containing alkoxysilane (Japanese Unexamined Patent Publication No. 82-114992).

However, the method for removing chlorine in alkoxysilane disclosed above has the following problems. In other words, when producing alkoxysilane by reacting chlorosilanes and alcohols, the method of coexisting a basic compound such as sodium alcoholate revealed that the disproportionation reaction of alkoxyhydrosilane was not possible as a result of retesting by the present inventors. The concentration of chlorine in the alkoxysilane produced is reduced to a certain level, for example 10 pp by weight
It has been found that it is extremely difficult to reduce the diameter to about m or less. Although the cause cannot be precisely determined, it is presumed that impurities caused by hydrolyzable chlorine such as hydrogen chloride or chlorosilane can be removed, but impurities caused by non-hydrolyzable chlorine such as alkyl chloride are not removed. . In addition, in the above method, if an excess of basic compounds is used to increase the removal efficiency of impurities caused by non-hydrolyzable chlorine, the disproportionation reaction of alkoxyhydrosilane will be accelerated and flammable silane gas will be generated. , which also turned out to be dangerous. In addition, in the method of removing chlorine impurities in alkoxysilane using metallic sodium, the chlorine content can be reduced to a desirable level, probably because both impurities caused by hydrolyzable chlorine and non-hydrolyzable chlorine can be removed. However, since metallic sodium is a solid, it reacts slowly and is dangerous to handle, making it unsuitable for industrial use. Furthermore, the alkoxysilane purification method includes a step of heat-treating the alkoxysilane in the presence of acid clay or a metal halide, a step of neutralizing the alkoxysilane with a neutralizing agent, and a step of removing the neutralized salt. Although both impurities caused by non-hydrolyzable chlorine can be removed, there is a problem that the number of purification steps is as many as three, making it unsuitable for industrial implementation.

Purpose of the Invention The present invention solves problems associated with conventional techniques such as low chlorine removal efficiency, large loss of alkoxysilane, or unsuitability for implementation on an industrial scale when removing chlorine from alkoxysilane. The purpose of this invention is to provide a method for removing chlorine in alkoxysilane that can be removed efficiently and inexpensively by an extremely simple method.

Summary of the Invention The method for removing chlorine from alkoxysilane according to the present invention is based on the general formula H S l(OR) 4-n n [wherein R is an organic group having 1 to 8 carbon atoms, n
is an integer from 0 to 3. ] When removing chlorine derived from a chlorine compound contained in the alkoxysilane represented by ゜, the alkoxysilane containing chlorine is brought into contact with a basic anion exchange resin.

According to the present invention, a chlorine-containing alkoxysilane,
By contacting with a basic anion exchange resin, the chlorine content in the alkoxysilane can be reduced in one step without loss due to disproportionation reaction of the alkoxysilane.

DETAILED DESCRIPTION OF THE INVENTION The method for removing chlorine from alkoxysilane according to the present invention will be specifically described below.

Alkoxysilanes In the chlorine removal method according to the present invention, the alkoxysilanes to be subjected to chlorine removal treatment have the general formula H S l (OR) 4-n n [wherein R has 1 to 8 carbon atoms] is an organic group having n
is an integer from 0 to 3. ] It is an alkoxysilane represented by.

Specifically, such alkoxysilanes include:
Trimethoxysilane, triethoxysilane, tri (2
-methoxyethoxy)silane, tri(2-ethoxyethoxy)silane, tribroboxysilane, trihexyloxysilane, tri(t-butoxy)silane, tri(
sec-butoxy)silane, triphenoxysilane, tribendioxysilane, tri(phenylethyloxy)
Silane, diethoxysilane, dibroboxysilane, di(
2-methoxyethoxy)silane, di(2-ethoxyethoxy)silane, diphenoxysilane, dibendyoxysilane, di(phenylethyloxy)silane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetrabutoxysilane, etc. can be mentioned.

Such alkoxysilanes contain impurities caused by hydrolyzable chlorine such as hydrogen chloride or chlorosilanes, and impurities caused by non-hydrolyzable chlorine such as alkyl chlorides.

The above-mentioned chlorosilanes have the general formula H S
t CD (OR) 4-(n+1)nfll [wherein, R is an organic group having 1 to 8 carbon atoms, and n
is an integer of 0 to 3, m is an integer of 1 to 3, and n+m is an integer of 1 to 3.

] It can be expressed as

In addition, the above alkyl chlorides have the general formula RCj7 [wherein R is the same as above]. ].

The content of chlorine compounds in such alkoxysilanes varies depending on the manufacturing method of the alkoxysilane, but generally the content of chlorine compounds in the alkoxysilane is 15 parts by weight as chlorine.
It is often contained in amounts ranging from pm to 500 ppm by weight.

Basic anion exchange resin In the method for removing chlorine in alkoxysilane according to the present invention,
A chlorine-containing alkoxysilane is contacted with a basic anion exchange resin.

The basic anion exchange resin used in the present invention is an ion exchange resin that exchanges anions, and is generally used as an exchange group on a three-dimensionally polycondensed polymer base such as a quaternary ammonium salt or a primary to tertiary It is preferable to have a structure in which an amine is bonded.

A copolymer of styrene and divinylbenzene is preferably used as the above-mentioned polymeric substrate.

An example of the structure of the above basic anion exchange resin is shown below.

In addition, in an anion + exchange resin having quaternary ammonium as an exchange group, the exchange group can generally be expressed as 1-NR OH, and for example, when a hydrochloric acid solution is added, the following ion exchange is thought to occur.

+ -NR OH +HCff→ -NR3CfI+H20 On the other hand, in anion exchange resins having primary amines, secondary amines, and tertiary amines as exchange groups, the following adsorption is thought to occur.

Cg Such basic anion exchange resins include Diaion SAIIA and SAIOA manufactured by Mitsubishi Kasei.
SSAIIB SSAIOB, PA30B, P
A308, PA312, PA316, PA31B
, HPA SSA21A SSA20^, SA21B
SSA20B SPA40B, PA408, PA4
12, PA41B, PA418, W^10, WAL
L, WA20, VA21, WA30, Rohm and Haas Amberlight IRA 400, IRA 401
, IRA 402 , IRA 405 , IRA 4
25, IRA430, IRA900, IRA
904, IRA 938, IRA 410, IRA
411, IR^910, IRA 911 SI
RA 88, IRA 45, IRA 47, IRA 9
3, [RA 94, Amberlist A-26, ^-27
, A-21, Sumitomo Chemical Duolite AIOID
, A143, A104, A109, A102D SA1
61, Al81TRSAAl62, ^171P SA13
2, ES137, A377, ^308, A378, A
368, A30BSA57, A43B, A34G,
A374, A561, A4, A6, A7, Dow Chemical DOWEX DOWEX 11 DOWEX 2, DOWEX 11, DOW! -X21K, MSA
Examples include I, MY^1, and WGR.

In the present invention, among the above basic anion exchange resins, Tire Ion wAlO, WAIL, WA20, manufactured by Mitsubishi Kasei,
W^21, WA30, Rohm and Haas Amberlist A-21, Amberlite IRA 45, IRA
47, IRA 93, IRA 94, Sumitomo Chemical Duolite A374, A581, A4, A6, A7,
Particularly preferably used are ^377, ^308, A378, A368, DOWEX ■^l manufactured by Dow Chemical, and VGR.

The basic anion exchange resin in the present invention can be used in an amount such that the ion exchange capacity of the basic anion exchange resin is 1 to 300 equivalents relative to the number of Durham atoms of chlorine contained in the alkoxysilane. preferable.

The mechanism by which chlorine impurities in the alkoxysilane are removed by bringing such a basic anion exchange resin into contact with an alkoxysilane containing chlorine is not clear, but the nitrogen atoms in the basic anion exchange resin are removed. It is presumed that this is because the chlorine derived from the chlorine compounds contained in the alkoxysilanes forms a chloride salt, and the chlorine in the alkoxysilane is adsorbed to the basic anion exchange resin. Ru.

Contact Conditions Contact between the alkoxysilane containing a base and the basic anion exchange resin is usually carried out by passing the alkoxysilane through a column filled with the basic anion exchange resin. Specifically, for example, a method in which a chlorine-containing alkoxysilane and a basic anion exchange resin are contacted in a fixed bed method, a method in which they are brought into contact in a moving bed method, a method in which they are brought into contact in a fluidized bed method, etc. are adopted. can do. Further, depending on the case, the chlorine-containing alkoxysilane and the basic anion exchange resin may be brought into contact in a batch manner.

The contact time between the chlorine-containing alkoxysilane and the basic anion exchange resin is determined by the liquid hourly space velocity (L.H.S.V.).
0.5 to 10 hours - 'good*L, < is about 1 to 5 hours -1. The temperature during contact is preferably -70 to 8,000 to suppress the disproportionation reaction of alkoxysilane.
It is desirable that the temperature is 0°C, more preferably 0 to 50°C.

Effects of the Invention According to the present invention, chlorine impurities in alkoxysilane can be efficiently removed by an extremely simple method. That is, according to the present invention, chlorine in the alkoxysilane is adsorbed and removed by the basic anion exchange resin as a chloride salt, so the step of separating the generated chloride salt from the alkoxysilane by distillation or the like is omitted. I can,
Therefore, the effect of completely eliminating loss of alkoxysilane can be obtained. Further, according to the present invention, loss due to disproportionation reaction of alkoxysilane can also be suppressed to 1% by weight or less.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Note that % and ppm in the examples are based on weight unless otherwise specified.

Example 1 According to the method described in JP-A-54-183529, metal silicon powder and cuprous chloride as a catalyst were mixed in a dibenzyltoluene solvent using a 10 g flask.
While heating to 20° C., methanol was continuously supplied and vapor containing trimethoxysilane was continuously removed.

In 100 g of trimethoxysilane produced above, the chlorine compound contained 30 ppm as a chlorine concentration and 8.5×10 −5 gram atoms as 1 chlorine amount.

Amberlyst A-21 (registered trademark manufactured by Rohm and Haas), a weakly basic anion exchange resin, was applied to a column with a cross-sectional area of 1 cd and a length of 50 cn+ (3 g (13.5 to 15 cm)).
x 10-3 equivalents), and 100 g of the above trimethoxysilane was passed from the top of the column at room temperature, normal pressure, and liquid space velocity for 5 hours.

When the chlorine content in 99.6 g of recovered trimethoxysilane was determined by a combustion method, the chlorine concentration was 10 ppm. As a result of gas chromatography analysis, the amount of tetramethoxysilane produced by the disproportionation reaction was 1% or less relative to trimethoxysilane.

Example 2 Tetramethoxysilane was obtained by fractionating the methoxysilane fraction produced in Example 1.

100 g of tetramethoxysilane produced above contained a chlorine compound with a chlorine concentration of 30 ppm and a chlorine amount of 8.5 x 10''-5 gram atoms.Except that 100 g of the above tetramethoxysilane was used. Chlorine impurity removal treatment was performed in the same manner as in 1.

As a result, the amount of tetramethoxysilane recovered was 99.8g.
When the chlorine content was determined using the combustion method, the chlorine concentration was . It was toppm.

Example 3 Triethoxysilane was produced from metallic silicon and ethanol in the same manner as in Example 1 according to the method described in JP-A-54-63529.

In 100 g of triethoxysilane produced above, the chlorine compound had a chlorine concentration of 32 ppm and a chlorine amount of 9. It contained 10-5 gram atoms of OX. Example 1 except that 100 g of the above triethoxysilane was used.
Chlorine impurity removal treatment was performed in the same manner as above.

As a result, the amount of triethoxysilane recovered was 99.7 g, and when the chlorine content was determined by a combustion method, the chlorine concentration was 1 1 ppm. Note that the amount of tetraethoxysilane produced was 1% or less based on triethoxysilane.

Comparative Example 1 In Example 1, when producing trimethoxysilane, 7.9×10−2 g of tri-n-butylamine (4.3×
100 g of trimethoxysilane was produced in the same manner as in Example 1, except that IN (4 gram equivalents) was coexisting. An attempt was made to remove the basic compound and/or its chloride salt by distillation, but a disproportionation reaction progressed during distillation and silane gas began to be generated, which was dangerous. Distillation was discontinued. When the chlorine content in the recovered trimethoxysilane was determined by a combustion method, the chlorine concentration was 15 pI) Im. The amount of tetramethoxysilane produced in the disproportionation reaction is
As a result of gas chromatography analysis, it was found that the amount was about 10% relative to trimethoxysilane.

Claims (1)

[Claims] (1) General formula H_nSi(OR)_4_-_n [wherein R is an organic group having 1 to 8 carbon atoms, n
is an integer from 0 to 3. ] When removing chlorine derived from chlorine compounds contained in alkoxysilanes represented by Removal method.