CS267101B1 - Method of organosiliceous esters preparation - Google Patents

Abstract

Organosilic esters of N-di-alkoxypolydimethylsiloxanes are prepared by reaction neutral product of dimethyldichlorosilene hydrolysis and 2-ethylhexanol with hydroxide potassium. The reaction mixture is heated to 140-160 ° C and then maintained temperature in this range and the current azeotropic water removal decreases smoothly pressure in the reaction space depending to a decreasing return flow rate to removing the water of reaction. Substances prepared this is the brake component hydraulic and lubricating fluids.

Description

The invention relates to a process for the preparation of organosilicon esters - dialkoxypolydimethylsiloxanes.

Organosilicon esters - dialkoxypolydimethylailoxanes They are described in MS. A.O. 239 977. Prepares by reacting the neutral product of the hydrolysis of dimethyldichlorosilane and monohydric alcohols with potassium hydroxide at a temperature of 120 to 260 ° C. During the reaction, the water formed by the reaction must be removed. For this purpose, a co-solvent can be used, with which the water forms an azeotropic mixture. The use of toluene or xylene is known. 2-ethylhexanol can have the same function, which can be advantageously used especially in the case where this substance is a reactant, i.e. in the preparation of organosilicon esters - dialkoxypolyslloxanes, where the alkoxyl is derived from 2-ethylhexanol. After the reaction, the reaction mixture is neutralized with carbon dioxide or acid and then with alkali carbonate. After separation of the ee salt, the remaining moisture is removed by filtration through sodium carbonate. The crude product thus treated is further subjected to distillation. The front distillation fractions can be returned to the next operation.

It has now been found that the process for the preparation of these substances can be advantageously modified by the method which is the subject of the present invention. It consists in heating the reaction mixture containing the neutral product of the hydrolysis of dimethyldichlorositan, 2-ethylhexanol, potassium hydroxide and optionally a co-solvent such as toluene or xylene to a temperature of 140-160 ° C. Thereafter, while maintaining the temperature in this range and at the same time azeotropically removing the water of reaction, the pressure in the reaction space is continuously reduced depending on the decreasing reflux rate until the reactions of the formed water are distilled off and a vacuum of at least 8 kPa is reached.

- 2 267 101

Carrying out the reaction under reduced pressure makes it possible to use lower reaction temperatures and to speed up the process. In this way, it is possible to easily increase the reactor capacity and to eliminate the circulation of large amounts of co-solvents on conventional equipment using, for example, a water ring pump.

Example 1

814 g of dimethyldichlorosilane hydrolysis product, 260 g of 2-ethylhexanol and 2 g of potassium hydroxide were introduced into a reactor equipped with a stirrer, a heating bath, a thermometer, an azeotropic nozzle, a water pump and a reduction valve. The reaction mixture was rapidly heated to 150 ° C with stirring and maintained at this temperature. Within 10 minutes the pressure was reduced to 44 kPa, during a further 15 minutes to 24 kPa, the pressure was reduced by foaming, until within 1.5 hours the pressure was reduced to 8 kPa and 20 ml of water were taken. After disconnecting the pump and cooling to about 50 ° C, the potassium hydroxide was neutralized by adding 20 ml of an aqueous solution of hydrochloric acid containing 0.04 mol of HCl with stirring for 20 minutes and the excess acid was neutralized by adding 20 ml of 20% aqueous sodium carbonate solution with stirring for 20 minutes. . After separating the salt solution, the product was dehumidified by filtration through a pad of sodium carbonate and the front portions were distilled off at a pressure of 1.6 kPa to a boiling point of 200 ° C. 807 g of water-clear product 6 with an acid number of 0.01 mg KOH / g, a viscosity at 100 DEG C. of 4.26 mm ^{@ 2} at 40 DEG C. were obtained.

O Ί Λ

101 mm.s ^- , solidification temperature -70 ° C, gas bubble formation temperature 330 ° C.

Example 2

The reactor of Example 1 was charged with the same amount of raw material po4 (c of Example 1) and 205 g of distillation fractions from Example 1 were added. to 6.6 kPa and 20 ml of water were taken in. Neutralization and distillation were carried out as in Example 1. 850 g of water-clear water were obtained.

- 3 267 101 products with an acid number of 0,01 mg / KOH / g, with a viscosity at

Λ Ol Λ Ol ^r

100 C 4.35 mm .s ~, at 40 C 101 mm .s ”, solidification temperature

-70 ° C, bubble formation temperature 350 ° C.

Example 3

An equal amount of the raw material of Example 1 was charged to the reactor of Example 1 and 10 mL of xylene was added. Proceeding as in Example 1, the mixture was heated to 140 DEG C., the pressure was reduced to 5.3 kPa over 2 hours and 20 ml of water were taken. Neutralization and distillation were carried out in the same way as in Example 1. 800 g of a water-clear product with an acid number of 0.01 mg KOH / g, a viscosity at 100 DEG C. of 4.30 mm @ -1, a freezing point of -70 DEG C., were obtained. gas bubble formation temperature 325 ° C.

Claims (1)

OBJECT OF THE INVENTION Process for the preparation of organosilicon esters of dialkoxypolydimethylsiloxanes by reacting the neutral product of the hydrolysis of dimethyldichlorosilane and 2-ethylhexanol with potassium hydroxide to remove the water of reaction at elevated temperature, characterized in that the reaction mixture is heated to 140-160 ° C and maintaining the temperature. simultaneous azeotropic removal of water continuously reduces the pressure in the reaction space depending on the decreasing reflux rate until the removal of the reaction water and reaching a vacuum of min. 8 kPa.