JPS6253516B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing N-arylaminoalkylalkoxysilane useful as a silane coupling agent with high purity and high yield. Conventionally, N-arylaminoalkoxysilanes used as silane coupling agents are as follows.
It is known that it can be synthesized by the methods of formulas (1) and (2). The reaction between an arylamine having an unsaturated group represented by formula (1) and hydrosilane uses an expensive platinum catalyst and also has an unfavorable yield. (2)
Although the method shown in the formula has the advantage of not using an expensive catalyst, it has the problems of low yield, easy formation of impurities during the reaction, and difficulty in purification. It was completely unknown until now. The present inventors have conducted intensive research on a method for producing N-arylaminoalkylalkoxysilane from the conventionally known arylamine of formula (2) and halogenated alkylalkoxysilane. The present invention was achieved by discovering a method for producing N-arylaminoalkylalkoxysilane in high yield. That is, the present invention provides (a) general formula

[Formula] (In the formula, A is a hydrogen atom, an alkyl group, an alkoxy group, or a vinyl group, and k is an integer from 0 to 5); (b) General formula (In the formula, X is Cl, Br or I, B is an alkylene group having 1 to 6 carbon atoms, R and R ¹ are 1 carbon number
to 10 monovalent hydrocarbon groups, m is an integer from 1 to 3, l is an integer from 0 to 2, where l+m
is 3. ) by fractional distillation of the heated reaction product with a halogenated alkyl alkoxysilane represented by the general formula (c) (In the formula, A, B, R, R ¹ , k, l and m are
In the method for producing N-arylaminoalkylalkoxysilane represented by The present invention relates to a method for producing N-arylaminoalkylalkoxysilane, which comprises distillation. The content of the present invention will be explained in detail below. The arylamine component (a) represented by the above general formula, which is a component of the raw material of the present invention, may be any primary amine, and has a benzene ring substituted with a hydrogen atom, an alkyl group, an alkoxy group, or a vinyl group. can use things. For example, the following can be used, but the invention is not limited thereto.
Aniline, P-toluidine, m-toluidine, O
-Toluidine, P-methoxyaniline, P-vinylaniline, m-vinylaniline, ethylaniline, propylaniline, xylidine, trimethylaniline, etc. The halogenated alkyl alkoxysilane, component (b), which is the other raw material of the present invention, is represented by the general formula described above, in which R and R ¹ have a carbon number of 1 to
10 monovalent hydrocarbon groups, including methyl group,
Alkyl groups such as ethyl, propyl and octyl groups; alkenyl groups such as vinyl and allyl groups;
Examples include aryl groups such as phenyl groups, and arylated alkyl groups such as phenylethyl groups and phenylpropyl groups. Preferred as R ¹ is an alkyl group. Also, X indicating a halogen atom
Among these, preferred is a chlorine atom. Next, examples of component (b) include γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, 2-methyl-3-chloropropyltrimethoxysilane, 3-methyl-4-chlorobutyltriethoxysilane, γ-Chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane, γ-bromopropyltrimethoxysilane, β-chloroethyltrimethoxysilane, α-
These include chloromethyl methyldimethoxysilane, δ-bromobutyltrimethoxysilane, and the like. N-arylaminoalkylalkoxysilane, which is a reaction product of component (a) and component (b), is a product of the reaction between component (a) and component (b).
A large number of compounds can be obtained depending on the type of component (b) used. Typical examples include N-(phenyl)γ-aminopropyltrimethoxysilane, N-(P-methylphenyl) γ
-aminopropyltrimethoxysilane, 2-methyl-N-(phenyl)3-aminopropyltrimethoxysilane, N-(phenyl)γ-aminopropyl methyldimethoxysilane, N-(P-vinylphenyl)γ-aminopropyltri Examples include ethoxysilane, N-(phenyl)β-aminoethyltrimethoxysilane, N-(phenyl)α-aminomethyltriethoxysilane, and the like. The reaction conditions of the present invention vary depending on the raw materials used, but can generally be carried out at a temperature of 50°C to 200°C, preferably 100 to 150°C. After the reaction is completed, the precipitated arylamine hydrogen halide compound is separated, a basic compound is added to produce a stable neutralized salt by-product, and the mixture is separated again. Note that the first distinction may be omitted to avoid complicated operations. In addition, if necessary, after removing excess arylamine, the desired N
-Arylaminoalkylalkoxysilane can be obtained. In this reaction, the arylamine can be used at least 2 times the mole of the halogenated alkyl alkoxysilane, but preferably 3 times the mole of the arylamine.
~6 times the mole. The present inventors discovered that when N-arylaminoalkylalkoxysilane is purified by distillation and separated and recovered from a reaction solution, halogen groups are present in the reaction solution.
It has been found that the presence of 2000 ppm or more significantly impairs the yield and purity of the target N-arylaminoalkylalkoxysilane. Although it is unclear in what form the halogen radical exists in this reaction solution, the main cause is thought to be the arylamine hydrogen halide salt produced as a by-product. In addition, free hydrogen halide may also be present in the form of a salt bound to the amine moiety of the product. Most of the arylamine hydrogen halide salts usually precipitate from the reaction solution, so they can be separated by excessive operations, but since they have some solubility in the raw materials and products, some amount can be separated. will be mixed into the reaction solution. In particular, when a large amount of arylamine is used, the amount of dissolved arylamine also increases. Although the effect of the halogen radical during distillation is not completely understood, one example is that the cyclization reaction of N-arylaminoalkylalkoxysilane shown by formula (3) is caused by the halogen radical. was found to be promoted by the presence of As a result of the side reaction represented by formula (3), the yield of the target product decreases and additional costs are required for purification. The present inventors have determined that this hydrogen halide salt concentration is
As a result of examining the effects on reaction yield and purity, it was found that as long as the concentration of halogen radicals in the reaction solution is 2000 ppm or less, there is virtually no negative effect on yield, etc. Theoretically, eliminating halogen radicals would produce the most desirable effect;
It is necessary to add special equipment and operations to the manufacturing process, which results in an increase in costs. Therefore, the simple and most effective method for reducing the amount of free halogen radicals in the reaction solution is to add a basic compound to the heated reaction product to generate a stable neutral salt by-product. This is a method of removing it in excess. As the basic compound, sodium carbonate, sodium methylate, triethylamine, etc. are used. The timing of addition of the basic compound is not particularly limited, and it may be added between the end of the reaction and the time of purification distillation. Furthermore, the heated reaction product may be cooled before or after the addition of the basic compound. The N-arylaminoalkylalkoxysilanes produced according to the present invention are useful as silane coupling agents, such as glass fiber treatments for laminates, rubber or resin filler treatments, rubber or resin additives, It has many uses such as a surface modifier for resins, an additive for paints, a primer, and various adhesive agents. Next, an example will be given and explained. In the examples, % means weight %. Reference example 1 Aniline in a reaction pot made of 200 glass lining
70.3 kg (756 mol) was charged, and while stirring, the liquid was heated with steam to a temperature of 130 to 140°C.
γ-chloropropyltrimethoxysilane 30.0Kg
(151 mol) was gradually added dropwise over 2 hours so that the liquid temperature could be maintained at 130-140°C, and after the addition was completed,
The reaction was carried out at 130-140°C for 3 hours. After cooling, the aniline hydrochloride precipitated in the reaction solution was filtered, and the resulting solution was heated to remove excess raw materials at a vacuum degree of 50 mmHg and a solution temperature of 100° C. to obtain 34.5 kg of a distilled crude solution. This crude liquid is
It contained 8000 ppm of chlorine. Add 50 kg of toluene, cool to 5℃ and leave overnight.
After filtering out the precipitated salt, reduce the pressure to 50mmHg and reduce the liquid temperature.
Toluene was distilled off at 100°C. When the chlorine content was measured again, it had dropped to 1400ppm. This concentrated liquid before purification is subjected to vacuum simple distillation, and the boiling point is
A fraction of 28.9 kg of a pale yellow transparent liquid was obtained at 123-141°C [degree of vacuum: 2 mmHg]. Analysis by NMR and gas chromatography showed that this fraction contained the target substance N-(phenyl)γ-aminopropyltrimethoxysilane with a purity of 95.4%, a refractive index (25°C) of 1.5049, and a chlorine radical of 800 ppm. It was hot. The yield was 75% based on the starting material γ-chloropropyltrimethoxysilane. Reference Example 2 The raw materials, amounts used, and reaction conditions used in Reference Example 1 were the same, and the resulting distilled crude liquids were treated in various ways to prepare concentrated liquids with different chlorine radical contents before purification. Table 1 shows the results of investigating the relationship between this chlorine concentration and the purity and yield of the target product after distillation purification.
Shown below.

[Table] It can be seen from the above table that when the concentration of chlorine radicals in the concentrated solution before purification exceeds 2000 ppm, both the yield and purity of the target N-(phenyl)γ-aminopropyltrimethoxysilane decrease significantly. Example 1 25% of sodium methylate was added to 34.2 kg of distilled crude liquid (containing 7800 ppm of chlorine radicals) obtained using the same raw materials, usage amounts, and reaction conditions as used in Reference Example 1.
% methanol solution was added until the crude distillate became neutral. After standing overnight, the generated sodium chloride was filtered off. The chlorine content in the solution was 5 ppm.
The liquid was subjected to simple vacuum distillation. A fraction with a boiling point of 123 to 141°C (degree of vacuum 2 mmHg) was collected. Gas chromatography analysis revealed that this fraction contained the target product N
It contained 99.1% -(phenyl)γ-aminopropyltrimethoxysilane, its chlorine radical was below the detection limit, and the yield was 87% based on the starting material γ-chloropropyltrimethoxysilane. Example 2 465 g (5 moles) of aniline was charged into the 2 three-necked flask, and the flask was blown with N ₂ . The liquid temperature was heated to 150° C. while stirring, and 212.5 g (1 mol) of 2-methyl-3-chloropropyltrimethoxysilane was added dropwise, and the temperature was maintained for 10 hours after the completion of the addition. After the reaction was completed, the mixture was cooled and the precipitated aniline salt was filtered off.
The chlorine content in the liquid was 12,000 ppm. Add dry sodium carbonate to 5% of the total weight of the liquid,
After stirring for an hour, it was filtered through a glass filter. The chlorine content in this solution was reduced to 150ppm. The liquid was first distilled to remove excess aniline at 100°C under a vacuum of 50 mmHg, and then reduced to a boiling point of 130 °C under a vacuum of 1 mmHg.
229g of a slightly yellow fraction at ~135°C was recovered. The yield was 85% based on the 2-methyl-3-chloropropyltrimethoxysilane used, and the purity was 97.5% by gas chromatography analysis, with 5 ppm of chlorine radicals. It was confirmed by NMR that this fraction was 2-methyl-N-(phenyl)3-aminopropyltrimethoxysilane.

Claims (1)

[Claims] 1 (a) General formula (In the formula, A is a hydrogen atom, an alkyl group, an alkoxy group, or a vinyl group, and k is an integer from 0 to 5); (In the formula, X is Cl, Br or I, B is an alkylene group having 1 to 6 carbon atoms, R and R ¹ are 1 carbon number
to 10 monovalent hydrocarbon groups, m is an integer from 1 to 3, l is an integer from 0 to 2, where l+m
is 3. ) by fractional distillation of the heated reaction product with a halogenated alkyl alkoxysilane represented by the general formula (c) In the method for producing N-arylaminoalkylalkoxysilane represented by the formula (wherein A, B, R, R ¹ , k, l and m are as described above), a basic compound is added to the heated reaction product. 1. A method for producing N-arylaminoalkylalkoxysilane, which comprises adding the halogen radicals to 2000 ppm or less by separating the precipitates, and then distilling the halogen radicals.