Method for Producing 3-Chloropropyltrichlorosilane

This invention relates to a production method of 3-chloropropyltrichlorosilane.

The addition reaction of trichlorosilane to allyl chloride is disclosed in the report of J. W. Ryan [J. Am. Chem. Soc. 82, 3601 (1960)] and Japanese patent application laid-open No. 95,023/1976, but this reaction is accompanied with many side reactions, resulting in poor yield of 3-chloropropyltrichlorosilane. Further, Japanese patent publication No. 18,844/1969 discloses a method by way of a .gamma.-ray irradiation of Co-60, but the method is commercially disadvantageous and poor in practical value because the reaction apparatus used in the method is complicated and the initial cost is high.

The object of the present invention is to provide a method for producing 3-chloropropyltrichlorosilane in which the above-mentioned disadvantages of the prior art have been overcome, and 3-chloropropyltrichlorosilane is produced with a higher yield.

The production method of the present invention is characterized in carrying out the addition reaction of trichlorosilane to allyl chloride into 3-chloropropyltrichlorosilane, in the presence of dichloro-bis(triphenylphosphine) platinum (II) [Pt(PPh.sub.3).sub.2 Cl.sub.2 ].

According to the present invention, trichlorosilane is mixed with allyl chloride; dichloro-bis(triphenylphosphine) platinum (II) as a catalyst is added to the mixture; and reaction is carried out by heating the mixture at a temperature of 30.degree. to 160.degree. C. to produce 3-chloropropyltrichlorosilane. The mixing ratio by mol of trichlorosilane to allyl chloride is in the range of 1:1 to 4:1, preferably 1:1 to 2:1. The amount of Pt(PPh.sub.3).sub.2 Cl.sub.2 used is in the range of 0.01 to 0.5 % by mol, preferably 0.02 to 0.1 % by mol based upon one mol of trichlorosilane. The reaction temperature is in the range of 30.degree. to 160.degree. C., preferably 60.degree. to 120.degree. C. The reaction time is in the range of 1 to 10 hours. The reaction is carried out either under reflux under the atmospheric pressure or at a high temperature under pressure, but it is preferable to carry out the reaction under pressure. If necessary, a solvent such as chlorobenzene, xylene, toluene or the like may be used in the reaction.

The apparatus used in the production method of the present invention may be any one of batchwise type, continuous type, etc.

The characteristic feature of the present invention is that 3-chloropropyltrichlorosilane is obtained with a high yield by using dichloro-bis[triphenylphosphine] platinum (II) [Pt(PPh.sub.3).sub.2 Cl.sub.2 ] as the catalyst for the reaction.

In the reaction expressed by the following equation (1), chloroplatinic acid has heretofore been used as the catalyst for the reaction, but a side reaction expressed by the following equation (2) occurs, resulting in a notable reduction in the yield:

The catalyst of the present invention is characterized in that side reactions such as equation (2) are notably suppressed. As a result, the amount of byproducts is notably reduced to give a high yield of 3-chloropropyltrichlorosilane. On the other hand, platinum complexes other than the catalyst of the present invention, e.g. tetrakistriphenyl phosphine platinum (0), are entirely ineffective.

The following examples are given to illustrate the present invention but it is not intended to limit the scope of the invention.

Twenty three grams (0.17 mol) of trichlorosilane, 7.7 g (0.1 mol) of allyl chloride and 0.05 % by mol (based upon one mol of trichlorosilane) of a catalyst Pt(PPh.sub.3).sub.2 Cl.sub.2 were introduced into a 100 ml stainless steel pressure reactor. After sealing, reaction was carried out with stirring at a temperature of 100.degree. C. for 8 hours. After completion of the reaction, the reaction liquid was analysed. The results are shown in the Table mentioned below. The reaction yield of 3-chloropropyltrichlorosilane based upon the amount of allyl chloride was 82%.

Example 1 was repeated except that 20.3 g (0.15 mol) of trichlorosilane, 7.7 g (0.1 mol) of allyl chloride and 0.025 mol % of the catalyst were used. The results are shown in the Table.

Example 1 was repeated except that H.sub.2 PtCl.sub.6.6H.sub.2 O was used in place of the catalyst of Example 1. The results are shown in the Table.

Example 1 was repeated except that Pt(PPh.sub.3).sub.4 was used in place of the catalyst of Example 1. The results are shown in the Table.