SU1754718A1 - Method of organo-silicon hydrides synthesis - Google Patents

Abstract

The essence of the invention: the product is an organosilicon hydride of the general formula R4-nSiHn, where R is alkyl, halogen, 1 kil, alkenyl, prim-1-3; R-ari with n 1; 2. Reagent 1: R (4-n) SiCln, where R.n - above, Reagent 2: LIH. Reaction conditions: pressure 1 mm Hg. Art., solvent tetrahydrofuran, preliminary degassing of the starting materials in vacuum 1 s-11 10 mm Hg. 1 epf-ly, table 2.

Description

The invention relates to organosilicon compounds, namely to an improved method for producing organosilicon hydrides of the general formula R4-nSlHn

where R is alkyl, halogenated, alkenyl when n is 1-3; R aryl when n "1,2.

These compounds can be used to produce organosilicon monomers and polymers, as well as to obtain heat-resistant coatings and films.

A known method of producing element-organic hydrides by low-temperature catalytic reduction of compounds containing electronegative groups with alkali metal hydrides (sodium and lithium).

The alkali metal hydride is pre-activated with a 0.1-0.3 M solution of alkali metal borohydride in ether. The reaction is carried out in the same solution.

The disadvantage of this method is the need to activate an alkali metal hydride and the use of scarce and expensive borohydride metal.

The known methods of obtaining organosilicon hydrides using lithium hydride are carried out under severe conditions: long boiling, a large excess of lithium hydride, and the product yield does not exceed 30-50%.

The closest to the present invention is the method of producing organosilicon hydrides by reducing the corresponding organochlorosilanes with lithium hydride, which is taken in a ratio of 1: 3-6. The process is carried out in a solvent, dibutyl or diisoamyl ethers at boiling for 50-70 h, and the yield of the target product is 10-50%.

The disadvantages of the method are the low yield of the target product and the duration of the process.

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The purpose of the invention is to increase the yield and simplify the process by reducing its duration. Furthermore, the method allows to reduce the consumption of lithium hydride.

This goal is achieved by the fact that organochlorosilanes are reduced by lithium hydride, and the starting materials are degassed beforehand in vacuum at 1 mm Hg. Art., the process is carried out at a residual pressure

1 mmHg in tetrahydrofuran (THF). Moreover, organochlorosilane and lithium hydride are taken in a ratio of 1: 1.52, respectively.

The difference of the proposed method is the preliminary degassing of the starting materials in vacuum for 5 minutes (based on 0.1 mol of chlorosilane and the corresponding amount of lithium hydride) and the use of GTP as a solvent.

Example 1. Phenyldimethylsilane. 10.0 g of phenyldimethylorosilane (0.059 mol) and 0.7 g of lithium hydride (0.087 mol, 1.5-fold excess) are degassed in separate ampoules at 0.1-0.01 mm Hg. within 5 minutes and add 5-10 ml of tetrahydrofuran previously degassed according to the above procedure to each of them in vacuo. The chlorosilane solution is added to the LIH / THF suspension at the same pressure under vacuum. After a certain induction period, an exothermic reaction begins, which is completed in 5-10 minutes. After cooling, the solution is filtered and fractionated on a column. 7.3 g of phenyldimethylsilane are obtained (92%).

Bp 57 ° C / 20 mmHg v .; to 20 1.4988.

PRI mme R 2. Trimethylsilane. 10.0 g of trimethylchlorosilane (0.092 mol) and 1.1 lithium hydride (0.13 mol, 1.5-fold excess) are degassed while cooling in separate ampoules at 0.1-0.01 mm Hg. within 5 minutes and 5-10 ml of THF are added to each of them under vacuum. Chlorosilane solution is added to a suspension of Li H / THF at the same pressure in vacuum. After a certain induction period, an exothermic reaction begins, which is completed in 5-10 minutes. Cooling trimethylsilane is twice condensed into a cooled ampoule. The output of 5.8 g (85%). Bp b, 7 ° C / 760 mm Hg; d46 7 0.6375.

Froze Di-n-butylsilane. 10.0 g of dibutyl dichlorosilane (0.046 mol) and 1.12 g of lithium hydride (0.14 mol, 1.5% critical excess) are degassed in separate ampoules at 0.1-0.01 mm Hg. within 5 minutes and 5-10 ml of THF are added to each of them.

cM20 0.876;

The chlorosilane solution is added to a suspension of UH / THF at the same pressure in vacuum. After a certain induction period, an exothermic reaction begins, which is completed in 15-20 minutes. After cooling, the solution is filtered and fractionated on a column. 5.9 g of dibutylsilane (87%) are obtained, b.p. 158 ° C 760 mm Hg; po 20 1.4219; 0.7431.

PRI me R 4. Phenylmethylsilane. 10.0 g of phenylmethyldichlorosilane (0.052 mol) and 1.3 g of lithium hydride (0.16 mol, 1.5-fold excess in stoichiometry) are degassed in separate ampoules at 0.1-0.01 mm Hg. at

for 5 minutes under vacuum and add 5-10 ml of THF under vacuum to each of them. The chlorosilane solution is added to the LIH / THF suspension at the same pressure under vacuum. After some induction period

an exothermic reaction begins, which is completed in 10-15 minutes. After cooling, the solution is filtered, the filtrate is fractionated on a column. 5.8 g of phenylmethylsilane (91%) are obtained.

Prototype. 50 g (0.26 mol) of phenylmethyldichlorosilane, 14.0 g of lithium hydride (1.76 mol, 3.4-fold excess in stoichiometry) and 80 ml of diisoamyl ether are loaded into the cube of the distillation column. Phenylmethylsilane is sampled periodically and collected in a trap. After two days of boiling the reaction mixture, 30 ml of phenylmethylsilane and diisoamylic ester were obtained, from which 7.7 g (24%) of phenylmethylsilane was separated by further distillation. T. Kip. 140 ° C; to 20 1.5046.

PRI me R 5. Vinylethylsilane. 10.0 g of vinyl ethyl dichlorosilane (0.064 mol) and 1.5 g of lithium hydride (0.192 mol, 1.5 times stoichiometric excess) are degassed in separate ampoules at 0.1-0.01 mm Hg. within 5 minutes and 5-10 ml of THF are added to each in vacuo. The solution of chlorosilane is added to the suspension with the same

pressure. After a certain induction period, an exothermic reaction begins, which is completed in 10-15 minutes. After cooling, the solution is filtered, the filtrate is washed 4 times with 10 ml of water, dried

anhydrous sodium sulfate. Almost pure vinyl ethylsilane is obtained (4.3 g, 76%). Bp 47 ° C / 742 mm Hg; dV20 0,6940; to 20 1.4030.

PRI me R 6. Bis (y-trifluoropropyl) silane. 10.0 g of bis (y-trifluoropropyl) dichlorosilane (0.034 mol) and 1.08 g of lithium hydride (0.13 mol, 2-fold excess in stoichiometry) are degassed in separate ampoules at 0.1-0.01 mmHg. within 5 minutes and 5-10 ml of THF are added to each of them. The chlorosilane solution is added to the LIH / THF suspension at the same pressure under vacuum. After a certain induction period, an exothermic reaction begins, which is completed in 10-15 minutes. After cooling, the solution is filtered, the filtrate is fractionated on a column. 6.5 g of hydride (85%) are obtained. Ti.p., 126 ° C / 735 mmHg; oY ° 1.180; nD25 1.3423.

Example. (Chloromethyl) silane. 10.0 g of chloromethyltrichlorosilane (0.054 mol) and 2.6 g of lithium hydride (0.32 mol, 2-fold excess in stoichiometry) are degassed while cooling in separate ampoules at 0.1-0.01 mm Hg. within 5 minutes and 5-10 ml of THF are added to each of them. Chlorosilane solution is poured into a suspension of LiH / THF at the same pressure in vacuum. After a certain induction period, an exothermic reaction begins, which is completed after 15 minutes. After cooling, the solution is filtered and fractionated on a column. Yield 3.1 g (70%).

Example 8. Octylsilane, 10.0göctyltrich-lorsilane (0.04 mol) and 1.44 g (0.181 mol, 1.5-fold stoichiometry excess) of lithium hydride is degassed in separate ampoules at 0.1-0.01 mm Hg . Art. within 5 minutes and 5-10 ml of THF are added to each of them. The chlorosilane solution is added to the LIH / THF suspension at the same pressure under vacuum. After a certain induction period, an exothermic reaction begins, which ends in 5-15 minutes. After cooling, the solution is filtered, fractionated on a column. 5.2 g of octylsilane are obtained (90%). Bp 61 ° C / 20 mmHg; d420 0.7457; on 1,4253.

Some examples of specific performance and process results are summarized in Tables 1 and 2.

As can be seen from the results given in Table 1, the proposed method allows

to increase the product yield by 35-67%, reduce the process time by 96 times, reduce the consumption of lithium hydride by 3 times.

In addition, the method provides the ability to carry out the process without additional heat supply and significantly reduces energy costs.

As can be seen from the results presented in Table 2, the change in vacuum depth is from 0.1 to 0.01 mm Hg. at 5 minutes degassing, 0.1 mol of the reagent does not affect the product yield. Further increase

pressure leads to the loss of hydride and to the complete inhibition of the process. Degassing 0.1 mol of the reagent at 0.1 mm Hg. Art. within 5 minutes a maximum yield of silicone hydride is provided,

unchanged with increasing degassing time.

Claims (2)

1. A method for producing organosilicon hydrides of the general formula R4-nSiHn, where R is alkyl, halogenated, alkenyl when n "1-3; R is aryl at p 1.2, by reduction of organochlorosilanes with lithium hydride in a solvent, characterized in that, in order to increase the yield of the target product and simplify the process, the starting materials are degassed in vacuo at 1 10 -1 10 mm Hg, the process is carried out at a residual pressure of 1 10-1 10 mm Hg and tetrahydrofuran is used as a solvent. 2. A method according to claim 1, characterized in that the organochlorosilane and lithium hydride are taken in ratio of 1: 1.5-2, respectively. Table 1  The data obtained by the method described in the prototype. Note: The amount of PhMeaSiCI taken into the reaction is 0.1-1.15 mol, respectively. Output according to GLC. table 2