JPS62145092A - Method for recovering tert-butyldimethylchlorosilane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for recovering tert-butyldimethylchlorosilane, in particular to a method for recovering tert-butyldimethylchlorosilane, which is used as a silylating agent in the pharmaceutical industry. Since this is discarded as butyldimethylsilanol, it relates to a method of recovering it as tert-butyldimethylchlorosilane.

(Prior art) Currently, in the field of pharmaceutical manufacturing, protecting groups are created by reacting with an intermediate active hydrogen silylating agent during the synthesis process of pharmaceuticals, and after the desired reaction has taken place, hydrolysis is performed to create protective groups. The method of removing is widely used. As this silylating agent, tert-
Butyldimethylchlorosilane is widely used in nucleic acid synthesis, prostaglandin synthesis, and the synthesis of various natural products, and its usefulness has been recognized. It has the advantage of being relatively stable against reactive reagents, hardly undergoing hydrolysis in humid or neutral aqueous environments, and therefore easy to handle. In addition, it has the advantage that it can be selectively removed by fluorine ion F- in non-aqueous preparations.

However, this tert-butyldimethylchlorosilane is expensive, and after the desired reaction is completed, it is eliminated from the target product as tert-butyldimethylsilanol.
Since tert-butyldimethylsilanol hardly undergoes dehydration condensation even in the presence of acids or bases, the silylation waste liquid containing it is of no use and is disposed of. It is strongly desired to supply tert-butyldimethylchlorosilane at a low cost in order to make effective use of silanol.

(Structure of the invention) The present invention is a technique that can solve these problems.
The present invention relates to a method for recovering rt-butyldimethylchlorosilane, which is characterized by reacting tert-butyldimethylsilanol with phosphorus chloride to convert it to tart-butyldimethyldichlorosilane.

That is, as a result of various studies on the effective use of tert-butyldimethylsilanol, which had been discarded in the past, the inventors of the present invention reacted this tert-butyldimethylsilanol with phosphorus chloride such as phosphorus trichloride, phosphorus pentachloride, and phosphorus oxychloride. They discovered that this can be converted into tert-butyldimethylchlorosilane, and completed research on the reaction conditions and the like to complete the present invention.

The method of the present invention can be easily carried out by reacting tart-butyldimethylsilanol with phosphorus chloride. In order for this reaction to proceed quantitatively, it is necessary to add phosphorus chloride such as phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, etc. in an amount equal to or more than the same mole relative to tert-butyldimethylsilanol, but do not add more than necessary. Since this is not economical, tart-butyldimethylsilanol 1
The amount may be in the range of 1 to 1.2 moles, and by adding phosphorus chloride within this range, tert-butyldimethylsilanol is converted to tert-butyldimethylchlorosilane at a conversion rate of 100%.

This reaction does not require the use of any particular solvent, and in this case, the reaction may be carried out at a temperature between the melting point and boiling point of the target tert-butyldimethylchlorosilane, therefore at a temperature of 84 to 125°C. Depending on the situation, the reaction may be carried out in the presence of a chlorinated hydrocarbon solvent such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, etc. In this case, the reaction may be carried out at a temperature ranging from room temperature to the reflux temperature of the solvent.

The target tert-butyldimethyl cyclosilane can be quantitatively recovered with a purity of 99% or more by distilling off the unreacted phosphorus chloride and solvent after the reaction, and then purifying the residue by distillation. The tert obtained here
-Butyldimethylchlorosilane has the advantage that it can be used again as silylating agent.

Next, examples of the present invention will be described.

Example 1 1.02 g (0.77 mol) of tert-butyldimethylsilanol and 400 mQ of chloroform were charged into a four-bottle flask with an internal volume of IQ equipped with a stirrer, a sonic funnel, a condenser, and a thermometer. While stirring, 106 g (0.77 mol) of phosphorus trichloride was dropped into the mixture at room temperature from a submerged funnel, heated under reflux for 1 hour, then cooled to room temperature, and the reaction mixture was analyzed by gas chromatography. As a result, it was confirmed that the reaction mixture had been converted to tert-butyldimethylchlorosilane at a conversion rate of 100%.

Next, the solvent was distilled off from this reaction mixture, and the residue was purified by distillation.
85 g of t-butyldimethylchlorosilane (yield 73%)
was gotten.

In addition, when the tert-butyldimethylchlorosilane obtained here (sample A) was compared with tert-butyldimethylchlorosilane (sample B) synthesized from tert-butyllithium and dimethyldichlorosilane, it was found that The following results were obtained, and both had the same melting point and boiling point, confirming that Sample A could be reused as a silylating agent.

Example 2 100 g (0.76 mol) of tert-butyldimethylsilanol was charged into a four-bottle flask with an internal volume of IQ equipped with a stirrer, a dropping funnel, a condenser, and a thermometer. 117g (0,76 mol)
was gradually added dropwise from the dropping funnel, and then heated under reflux for 1 hour.
After reacting for a period of time and distilling the resulting reaction mixture,
99% purity tart~butyldimethylchlorosilane 7
2 g (63% yield) was obtained.

Example 3 126 g of phosphorus pentachloride was placed in a four-loop flask with an internal volume of IQ equipped with a stirrer, a dropping funnel, a condenser, and a thermometer.
(0.61 mol) and 200 mQ of carbon tetrachloride were added to the nitrogen solution, and 80 g of tert-butyldimethylsilanol (0.61 mol) was charged.
A mixed solution of 61 mol) and carbon tetrachloride 50IIIQ was gradually added dropwise from the dropping funnel at room temperature.

The reaction was then carried out under reflux for 2 hours, and then the solvent was distilled off from the reaction mixture, and the residue was distilled to give 59 g of tert-butyldimethylchlorosilane with a purity of 99% (yield: 6.
5%) was obtained.

Procedural amendment January 22, 1986

Claims (1)

[Claims] 1. A method for recovering tert-butyldimethylchlorosilane, which comprises reacting tert-butyldimethylsilanol with phosphorus chloride to convert it into tert-butyldimethylchlorosilane.