RU2035463C1 - Method of alkyldisilanes synthesis - Google Patents

Abstract

FIELD: organic chemistry. SUBSTANCE: product of the formula R₁-Si(R₂)₂-Si(R₂)₂-R₁ , where R₁ and R₂ - are similar or different alkyls; conversion is 98.0%. Reagent 1: R₁Cl₂Si-SiCl₂R₂. Reagent 2: R₂MgCl. Reaction conditions: in toluene medium with ethylated vat waste of methylchlorosilanes direct synthesis at their mass ratio (1:1)-(1:2) in the presence of ethyl ether. EFFECT: improved method of synthesis. 2 cl, 2 tbl

Description

 The invention relates to the chemistry of organosilicon compounds, in particular to methods for producing alkyldisilanes, which are used as reducing agents, etc.

 A known method of producing alkyl disilanes by the interaction of methylchlorosilanes with an alkyl halide in the presence of a metal (zinc, aluminum, magnesium) halogen acceptor and process activators (compounds of tin, antimony, mercury, copper, etc.). The disadvantage of this method is the need to use a whole gamut of compounds that pollute the final product.

A known method for producing alkyl disilanes (in particular hexamethyldisilane) by reacting methylchlorosilanes (possibly waste direct synthesis of methylchlorosilanes with a boiling point of 130-160 ^about C) with alkylmagnesium chloride (methylmagnesium chloride) using a specific solvent: a mixture of tetrahydrofuran and dimethoxybutane. The synthesis is carried out by the portion-wise addition of methylchlorodisilanes to the Grignard reagent (due to the difficulty of controlling the temperature of the exothermic process).

 The disadvantage of this method is its complexity, due to the need to work with a highly reactive and flammable Grignard reagent, the need to use significant quantities of fire hazardous donor solvents, the need for portioned administration of methylchlorodisilanes due to the difficulty of temperature control, especially in the initial stages of synthesis.

 An object of the invention is to simplify the process.

This problem is solved by the fact that in the method of producing alkyl disilanes by the interaction of methylchlorodisilanes with alkyl magnesium chloride in a specific solvent medium, a mixture of toluene and ethylated bottoms from the direct synthesis of methylchlorosilanes in their mass ratio (1: 1) - (1: 2) in the presence of sulfuric ether. As methylchlorodisilanes, bottoms from the direct synthesis of methylchlorosilanes with a boiling point of 130-160 ^о С are used, followed by isolation from the reaction mixture of the target product of alkyl substituted disilane and return of the remaining ethylated bottoms from the direct synthesis of methylchlorosilanes mixed with toluene at a toluene-ethylated bottoms weight ratio (1: 1) - (1: 2) as a solvent in the synthesis process.

 Such a process leads to its speed regulation by changing the ratio of toluene and leaded bottoms from the direct synthesis of methylchlorosilanes, and therefore to controlled heat generation, which eliminates the difficulties of temperature control, especially in the initial stages of synthesis, significantly reduces the amount of donor solvents, and eliminates the need for work with the highly reactive and flammable Grignard reagent, since it forms and is immediately exhausted in x Ode process, that is, significantly simplify the process.

 The regulatory effect of leaded bottoms from the direct synthesis of methylchlorosilanes on the organomagnesium synthesis is a new and unexpected factor not described in the literature.

SiSi

SiSi

+4MgCl₂ (2)
3EtMgCl+

SiSi

SiSi

+3MgCl₂ (3)
2MgCl+

SiSi

SiSi

+2MgCl₂ (4)
В результате процесса образуются в основном метилэтилдисиланы, преимущественно диметилтетраэтилдисилан. Продукт синтеза гидролизуют 3%-ной соляной кислотой, от органической фазы отгоняют растворители и перегонкой выделяют диметилтетраэтилдисилан. Оставшиеся этилированные кубовые отходы производства прямого синтеза метилхлорсиланов используют в смеси с толуолом при массовом соотношении толуол-этилированные кубовые отходы (1:1)-(1:2) в качестве растворителя для последующего получения алкилдисиланов.The synthesis process, taking into account the fact that the main component of bottoms waste from the direct synthesis of methylchlorosilanes are methylchlorosilanes, can be simplified by the following scheme:
Mg + EtCl ____ → EtMgCl (1)
4EtMgCl +

Sisi

Sisi

+ 4MgCl ₂ (2)
3EtMgCl +

Sisi

Sisi

+ 3MgCl ₂ (3)
2MgCl +

Sisi

Sisi

+ 2MgCl ₂ (4)
As a result of the process, mainly methylethyl disilanes, mainly dimethyl tetraethyl disilane, are formed. The synthesis product is hydrolyzed with 3% hydrochloric acid, solvents are distilled off from the organic phase and dimethyltetraethyl disilane is isolated by distillation. The remaining ethylated bottoms from the production of direct synthesis of methylchlorosilanes are used in a mixture with toluene at a mass ratio of toluene-ethylated bottoms (1: 1) - (1: 2) as a solvent for the subsequent production of alkyl disilanes.

 A distinctive feature of the invention is the use of a mixture of toluene and ethylated bottoms as a specific solvent for the direct synthesis of methylchlorosilanes in a weight ratio of (1: 1) to (1: 2) in the presence of sulfuric ether; as methylchlorosilanes, bottoms from the direct synthesis of methyl chlorosilanes with a boiling point of 130-160 ° C are used, followed by isolation from the reaction mixture of the target product of alkyl substituted disilane and return of the remaining ethylated bottoms from the direct synthesis of methyl chlorosilanes mixed with toluene at a toluene-ethylated bottoms weight ratio ( 1:) - (1: 2) as a solvent in the synthesis process.

 PRI me R 1 (illustrates the preparation of dimethyltetraethyl disilane and leaded bottoms from the direct synthesis of methylchlorosilanes).

500 g of magnesium with a size of 500 m granules 1.0-2.5 mm and feed down the first zone 1000 ml / h of a mixture of the composition: 210 ml (3,000 mol) of ethyl chloride, 160 ml of bottoms waste from the direct synthesis of methylchlorosilanes (1.175 g / cm ³ ), boiling point 130 -160 ^{° C,} a hydrolyzable chlorine content of 56.5% (3.0 mol chlorine), 100 ml of ether and 530 ml of toluene. At the top of the reactor (to the separator) 76 g / h of magnesium are supplied. The synthesis temperature is maintained by cooling the first and heating the fourth zone and the separator. The speed of rotation of the mixer is maintained within the range of 120-140 rpm. The synthesis product, which is a 30% suspension of magnesium salts with leaded bottoms (mainly up to 65% dimethyltetraethyl disilane) in toluene and sulfuric ether, is analyzed and hydrolyzed.

 Heat removal in the zones of the synthesis reactor, kcal / h: first 205 5; second 0, third 0.

 As shown by the data of heat removal, the synthesis process is very active and almost completed in the first zone of the reactor.

 The content of dimethyltetraethyl disilane in the synthesis product excluding toluene, sulfur ether and magnesium salts is 65%. The content of hydrolyzed chlorine in the liquid phase of the synthesis product is 2 g / kg, which indicates a 98% conversion of ethyl magnesium chloride.

The resulting synthesis product (1000 g) was charged for 30-40 minutes in a four-necked two-liter flask, loaded with 1000 ml of 3% hydrochloric acid and equipped with a stirrer with a water seal, a thermometer and a reflux condenser. Entering the synthesis product is carried out with cooling at a temperature of 30-50 ° ^C. The contents of the flask were stirred for 3 hours at 60 ^C. The contents of the flask was cooled, the toluene solution was separated acidic ethylated bottoms waste products of the direct synthesis of methylchlorosilanes, the solution was washed three times with water (po250 ml) and distilled in a 0.5 L Tabor flask with separation of the fraction with a boiling point of 211.5-213 ^about C (dimethyltetraethyl disilane with a purity of 94.7%). Of the 6 hydrolysis operations, 290 g of dimethyltetraethyl disilane with a purity of 94.7% were isolated. The remaining toluene solution of leaded bottoms from the production of direct synthesis of methylchlorosilanes (toluene content is 50%, the content of leaded bottoms from the production of direct synthesis of methyl chlorosilanes 50%, including 24% of dimethyl tetraethyl disilane) in an amount of 2, 7 l is used as a solvent to obtain the alkyl disilanes of Example 2.

 PRI me R 2. The synthesis process is carried out analogously to example 1, using as a solvent a mixture of toluene with ethylated bottoms from the direct synthesis of methylchlorosilanes production with a mass ratio of toluene-ethylated still bottoms 1: 1 obtained in example 1.

 The composition of the synthesis mixture: 210 ml (3.0 mol) of ethyl chloride, 160 ml of bottoms from the production of direct synthesis of methylchlorosilanes (as in example 1), 100 ml of sulfuric ether and 530 ml of a mixture of toluene and ethylated bottoms from the production of direct synthesis of methylchlorosilanes, obtained according to example 1, with a mass ratio of toluene-ethylated bottoms waste 1: 1.

 Synthesis product characteristics: dimethyltetraethyl disilane content (excluding toluene, sulfur ether and magnesium salts) 55% hydrolyzable chlorine content 4.5 g / kg, which indicates 95.5% ethylmagnesium chloride conversion.

 The heat removal over the zones of the synthesis reactor at various feed rates of the mixture is shown in Table 1.

 As shown by the data of heat removal, the synthesis process is less active in the first zone of the reactor (by about 25%) and ends in the second zone of the reactor (compare with the data of example 1), i.e. the use of a mixture of toluene and leaded bottoms as a specific solvent for the direct synthesis of methylchlorosilanes with a mass ratio of 1: 1 allows the process speed to be reduced and the thermal effect of the synthesis to be distributed over a larger number of reactor zones.

 Of the 6 hydrolysis operations of the synthesis product, 350 g of dimethyltetraethyl disilane with a purity of 97.4% were isolated. The remaining toluene solution of ethylated bottoms from the direct synthesis of methylchlorosilanes (toluene content is 33%, the content of ethylated bottoms from the direct synthesis of methylchlorosilanes is 67%, including 25% of dimethyltetraethyl disilane). 2.8 l is used as a solvent for the production of the alkyl disilanes of Example 3.

 PRI me R 3. The synthesis process is carried out analogously to example 2, using as a solvent a mixture of toluene with ethylated bottoms from the direct synthesis of methylchlorosilanes with a mass ratio of toluene-ethylated bottoms from 1: 2 obtained in example 2.

 The composition of the synthesis mixture: 210 ml (3.0 mol) of ethyl chloride, 160 ml of bottoms from the production of direct synthesis of methylchlorosilanes (as in examples 1 and 2), 100 ml of sulfuric ether and 530 ml of a mixture of toluene and ethylated bottoms from the production of direct synthesis of methylchlorosilanes obtained in example 2, when the mass ratio of toluene-ethylated bottoms waste 1: 2.

 Synthesis product characteristics: dimethyltetraethyl disilane content (excluding toluene, sulfur ether and magnesium salts) 52% hydrolyzable chlorine content 4 g / kg, which indicates a 96% conversion of ethyl magnesium chloride.

 Heat removal in the zones of the synthesis reactor, kcal / h: first 90; second 125; third 0.

 Of the 6 hydrolysis operations of the synthesis product, 410 g of dimethyltetraethyl disilane with a purity of 95.6% were isolated. The remaining toluene solution of ethylated bottoms from the direct synthesis of methylchlorosilanes (toluene content is 33%; the content of ethylated bottoms from the direct synthesis of methylchlorosilanes is 67%, including 26% dimethyltetraethyl disilane) in the amount 3.0 l is used as a solvent for the production of the alkyl disilanes of Example 4.

PRI me R 4. The synthesis process is carried out analogously to example 2, using as a solvent a mixture of toluene with ethylated bottoms from the direct synthesis of methylchlorosilanes with a mass ratio of toluene-ethylated bottoms from 1: 2, obtained in example 3. As alkylchlorosilane use dimethyltetrachlorodisilane with a boiling point of 150-155 ^about C.

 The composition of the synthesis mixture: 210 ml (3.0 mol) of ethyl chloride, 171 g (3.0 mol of chlorine) dimethyltetrachlorodisilane, 100 ml of sulfur ether and 530 ml of a mixture of toluene with ethylated bottoms from the production of direct synthesis of methylchlorosilanes obtained in example 3, with a mass ratio of toluene-ethylated bottoms of 1: 2.

 Synthesis product characteristics: dimethyltetraethyl disilane content 65% (excluding toluene, sulfuric ether and magnesium salts); the content of hydrolyzable chlorine of 2.0 g / kg, which indicates a 98% conversion of ethylmagnesium chloride.

 Heat removal in the zones of the synthesis reactor, kcal / h: first 90; second 125; third 0.

 Of the 6 operations of hydrolysis of the synthesis product, 820 g of dimethyltetraethyl disilane with a purity of 95.6% were isolated. The results of examples 1-4 are shown in table 2.

 As can be seen from the data given in the examples, the use of a mixture of toluene and leaded bottoms as a specific solvent for the production of direct synthesis of methylchlorosilanes with their mass ratio (1: 1) - (1: 2) in the presence of sulfuric ether and the use of bottoms as methylchlorodisilanes the production of direct synthesis of methylchlorosilanes with a boiling point of 130-160 ° C, followed by isolation from the reaction mass of the target product of the alkyl substituted disilane and returning the remaining leaded bottoms in the production of direct synthesis of methylchlorosilanes with a mixture with toluene at a mass ratio of toluene, ethylated bottoms (1: 1) - (1: 2) as a solvent in the synthesis process allows you to distribute the thermal effect of the process along the height of the synthesis reactor, that is, to control the speed of the process by changing the amount leaded bottoms from the production of direct synthesis of methylchlorosilanes mixed with toluene in the presence of sulfuric ether, especially in the initial stages (in the first zone it is possible to reduce heat from 205 to 90 kcal / h, t .e. more than twice), eliminates the need for preliminary preparation of Grignard reagent and work with it and allows to reduce the amount of donor solvent. Thus, a significant simplification of the process is achieved.

 Other advantages of the process are: a high degree of conversion of ethylmagnesium chloride (95.5-98.0%); the possibility of utilizing waste products from the direct synthesis of methylchlorosilanes to produce a valuable product of dimethyltetraethyl disilane dimethyltetraethyl disilane; the possibility of concentrating individual components of ethylated bottoms after separation of dimethyltetraethyl disilane with a view to their subsequent isolation. The proposed method for controlling heat dissipation is much simpler in hardware design than those proposed for the synthesis of ethyl substituted silanes by separate synthesis of the Grignard reagent and ethyl chlorosilanes from it by height or by reagent input of the reagents along the height of the apparatus.

 As follows from Table 2, a decrease in the content of ethylated bottoms from the direct synthesis of methylchlorosilanes in a mixture with toluene of less than 50% will not lead to a significant decrease in heat generation from the first zone of the synthesis reactor, and an increase in the content of more than 67% will lead to a significant shift of the process to the second zone, which is also impractical.

Claims (2)

 1. METHOD FOR PRODUCING ALKYLDISILANES by reacting methylchlorodisilanes with alkylmagnesium chloride in an organic solvent medium, characterized in that a mixture of toluene and ethylated bottoms from the direct synthesis of methylchlorosilanes with a mass ratio of 1 1 1 2 in the presence of sulfuric ether is used as an organic solvent. 2. The method according to claim 1, characterized in that bottoms from the production of direct synthesis of methylchlorosilanes with a boiling point of 130 160 ^° C are used as methylchlorodisilanes, followed by isolation from the reaction mass of the target product of alkyl substituted disilane and return of the remaining ethylated bottoms from the production of direct synthesis of methylchlorosilanes to mixtures with toluene at a mass ratio of toluene: leaded bottoms 1 1 1 2 as solvent in the synthesis process.

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