DE1157614B - Process for the preparation of 1, 9-dihalodecaorganopentasiloxanes - Google Patents

Description

GERMAN

PATENT OFFICE

N 21455 IVb / 12 ο

REGISTRATION DATE: A P RIL 14, 1962

NOTICE THE REGISTRATION ANDOUTPUTE EDITORIAL; NOVEMBER 21, 1963

The invention relates to the preparation of 1,9-dihalodecaorganopentasiloxanes from octaorganocyclotetrasiloxanes and diorganodihalosilanes according to the general equation

RTTSiX ₂ + (R '"R""SiO) 4

R "

> X-Si

R '

- O

R '" -Si R""

in which R ', R ", R'" and R "" = alkyl, aryl or Alkenyl radicals and X is a halogen atom.

According to one proposed by W. Patnode and D. F. Wilcock (J. Amer. Chem. Soc, 68, p. 358 [1946]) Method for the preparation of α, ω-dichloropolydimethylsiloxanes

Cl - Si (CHa) ₂ [- O - Si (CH ₃ ) 2] »Cl

partial hydrolysis of dimethyldichlorosilane gives the homologue η - A only in yields of less than 10% of theory. In addition, the separation of the individual homologs from one another, which arise in the mixture, is associated with a laborious rectification in a vacuum. KA Andrianow et al. described a telomerization between octamethylcyclotetrasiloxane and dimethyldichlorosilane or vinylmethyldichlorosilane (Nachr. akad. Wiss. USSR, Abt. Chem. No. 8, pp. 1456 [1961], and no. 10, pp. 1788-1961]). They also received a mixture of homologues, from which the homologue η - 4 could be separated off by rectification in a yield of 16% of theory.

Surprisingly, it has now been found that the reaction can be carried out in such a way that the homologue η = 4 is formed almost exclusively. For this it is necessary to prevent any contact of the starting compound with the autoclave material if it is made of metals, e.g. B. stainless steel, or if this autoclave structural parts such. B..valve, pressure gauge and thermometer connector, with which the reaction vapors could come into contact. It has been shown in these cases that ^{a mixture of all theoretically possible homologues is formed even at temperatures below 100 °} C., which means that the four-unit of cyclotetrasiloxane is split into smaller fragments, which then process for production

of 1,9-dihalodecaorganopenta-

siloxanes

Applicant:

Imperial Chemical Industries Limited, Stevenston, Ayrshire (Great Britain)

Representative: Dr.-Ing. H. Fincke, Dipl.-Ing. H. Bohr and Dipl.-Ing. S. Staeger, patent attorneys,

Munich 5, Müllerstr. 31

Dr. Heinz Niebergall, Frankfurt / M., Has been named as the inventor

participate in the reaction. Traces of Lewis acids, e.g. B. SbCIs, suffice to this splitting can be caused even at lower temperatures.

The cleavage of the four-unit of the cyclotetrasiloxane can be avoided in that the Reaction is carried out in a glass vessel. To get flawless results, you have to do it it must be ensured that the starting compounds do not distill from the glass vessel into the autoclave and that liquid which has condensed on the autoclave material does not get into the glass vessel. this can easily be achieved by covering the glass vessel with a sufficiently thin and long one Seals the capillary and presses a dry gas into the autoclave, ζ. Β. technical nitrogen or carbon dioxide. The pressure should be high enough to avoid boiling.

So is z. B. the most favorable temperature for the reaction between dimethyldichlorosilane (I) and octamethylcyclotetrasiloxane (II) between 270 and 300 ° C with a reaction time of 4 hours. The pressure should be 80 to 120 atmospheres at room temperature. At a molar ratio of 1: 1 and 4 hours of heating at 300 ⁰ C is obtained 1,9-Dichlordecamethyltetrasiloxan (III) in a yield of 50% of theory. 12% of the used (I) and 16% of the used (II) are received back and can be used again. Other homo-

309 749/421

ioge are only obtained in smaller amounts, e.g. B. 16% η = 5 to 7.5% η = 3.

At a reaction ^{temperature of 270 °} C. and a molar ratio of 1: 1, 34% III are obtained. There are no lower or higher homologues. As a result of the large difference in the boiling point of I, II and III, the starting compounds I and II can be easily and quantitatively separated from III and used repeatedly for the reaction. The yield is almost quantitative.

At a molar ratio I: II = 1.5: 1 and a temperature of 300 ° C. for 4 hours, 70% of theory III, based on II, is obtained. 30% of I and 19% of II are received back in addition to 12% η = 3 and 15% η> 4.

At a molar ratio of I: II = 1: 1.5 and a temperature of 300 ° C. for 4 hours, 66% III, based on I, are obtained. 28% of II is recovered in addition to 9% η = 3 and In addition, in this case the rate of the subsequent reaction of III with II, which is still unchanged, is lower than in the presence of Lewis acids.

Any attempt to obtain the homologue η = 8 in a predominant amount by a subsequent reaction of III with unchanged II, e.g. B. by changing the molar ratio, leads to an equilibration, the whole series of homologues η = 1 to η> 8 is obtained.

At a molar ratio of I: II = 1: 2 and a temperature of 300 ^° C. for 4 hours, 81% III, based on I, is obtained. A reaction at 350 and 400 ⁰ C under the same conditions leading to 77 or 42% of III, based on I. From this it can be seen that temperatures above 300 ° C the formation of higher homologues at the expense of III cause.

A reaction that is carried out in Tantalautoklav without glass vessel at a molar ratio I: results in 9% III 1, at 200 ⁰ C for 4 hours, 4% R = 3 and 4% η> 4 in addition to unchanged I and II: II = 1 Under the same conditions, 10% III, 7% η = 3 and 8% higher result at 250 ° C

The boiling points of the formula = 6th = 8th subsequently snow-making Si (CH3) 2Cl Torr Homologues of [Si (CH ₃ ) 12th Torr Cl- Dimethyldichlorosilane C / 15 Torr are the following: 1 C / 15 Torr R = 2 35 ° C / 15 Torr R = 3 73 ° C / 15 Torr R = 4 (HI) 105 ° C / 15 Torr R = 5 131 ° C / 3 Torr R = 154 ° C / 15 Torr 117 ° C / 3 Torr R = 172 ° C / 3 .. 70 ° C / 760 Torr (I) 135 ° 246 ° C / 3rd R = 176 ° R =

Hexamethylcyclotri-

siloxane 28 ° C / 15 torr

Octamethylcyclotetra-

siloxane 68 ° C / 15 Torr (II)

In the reactions described below, in addition to the homologues given there, the homologues η = 1, η = 2 and hexamethyl-

Homologues. At 280 ⁰ C following products 35 are cyclotrisiloxane in small amounts. Because the quantities

obtained: 13% III, 11% η = 3, 9% η = 5, 7% η = 6 and 29% η > 6.

Further investigations in the tantalum autoclave have shown that the reaction is difficult to reproduce, because even traces of metallic impurities have a significant impact on the result.

Just like the experiments in the stainless steel autoclave, these in the tantalum autoclave do not lead to a predominant one or exclusive formation of III. In this case, too, all will be higher and obtain lower homologs that may arise according to the equilibration laws, if even at significantly higher temperatures, e.g. B. 300 ° C for tantalum corresponds to about 100 ° C for stainless steel.

are mostly insignificant, they are not included.

Reactions in a glass vessel Example 1

32.2 g dimethyldichlorosilane (I) and 74.0 g octamethylcyclotetrasiloxane (II) are placed in a glass vessel with a capacity of about 300 ml and the latter is closed with a capillary. The capillary should be a have a clear width of about 0.8 mm and be about 15 cm long. A ground joint is fused to it, the corresponding ground joint on the glass vessel. This closed glass vessel is placed in an autoclave

In the stainless steel autoclave, only 50 of about 11 contents are introduced ^{at 100 ° C. and are drier in this}

In addition to 6% η = 3 and 57%, 6% III receive higher homologs.

The results described above show that it is impossible to use in a steel or tantalum autoclave carry out a reaction which predominantly or exclusively leads to III. Other Metals are also unsuitable. The same applies to the presence of Lewis acids (as catalysts). This means that in the presence of metals, the reaction rate between II and I and that of the catalytic decomposition of II into smaller fragments and their further reaction with I are no longer sufficiently different from one another. As a result, III cannot do more than Main product emerge. However, in the absence of metals or Lewis acids, the rate of reaction is lower between II and I considerably larger than the breakdown of II into smaller fragments.

technical nitrogen of about 80 atmospheres.

For 4 hours is heated to 27O ⁰ C and rectified the reaction mixture, after cooling, with exclusion of moisture.

The following fractions are obtained:

21.2 g = 20% dimethyldichlorosilane (I) 49 g = 46% octamethylcyclotetrasiloxane (II) 36 g = 34% 1,9-dichloro-decamethylpentasiloxane (III).

Example 2

As stated in Example 1, 32.2 g of I and 74.0 g of II are ^{heated to 300 °} C. for 4 hours and the reaction mixture is rectified. The following are obtained:

12.7 g = 12% I.
17 g = 16% II

5.3 g = 5% homologue n = 3 53 g = 50% III
17 g = 16% homologue n = 5-7

Example 3

As stated in Example 1, 48 g I and g II are ^{heated to 300 °} C. for 4 hours and rectified. The following are obtained:

14.4 g = 30% of the I used 14 g = 19% of the II used 13 g = 12% of theory, homologue η = 3,

based on II 74 g = 70% of theory, III, based on II,

and
16 g = 15% of theory, homologue η > 4,

based on II

Example 4

As stated in Example 1, 32.2 g I and g II are ^{heated to 30O 0} C for 4 hours and rectified. The following are obtained:

6g = 19% of the I used 31 g = 28% of the II used 10g = 9% of theory, homologue η = 3,

related to I.

70 g = 66% of theory III, based on I, and 22 g = 21% of theory, homologue η> 4, based on I

Example 5

As stated in Example 1, 32.2 g I and g II are ^{heated to 300 °} C. for 4 hours and rectified. The following are obtained:

3 g = 9% of the I used 71g = 48% of the II used 5.3 g = 5% of theory, homologue η = 3,

related to I.
86 g = 81% of theory, III based on I,

and

15 g = 14% of theory, homologue η> 4, based on I.

Example 6

As stated in Example 1, 32.2 g I and g II are ^{heated to 350 °} C. for 4 hours and rectified. The following are obtained:

0.7 g = 2% of the I used 45 g = 30% of the II used

8 g = 8% of theory, homologue η = 3 81g = 77% of theory III, based on I 45 g = homologue η> 4

Example 7

As stated in Example 1, 32.2 g I and g II are heated to 400 ° C. for 4 hours and rectified. The following are obtained:

0.5 g = 1.5% of the I used 40 g = 27% of the II used 11g = 10% of theory, homologue η = 3,

related to I.

44 g = 42% of theory III, based on I 80 g = homologue η> 4, based on I comparative experiments

a) 64.4 g of I are heated with 148 g II directly in Tantalautoklav of 1 1 content without glass vessel 4 hours at 200 ⁰ C. Before this, dry nitrogen is injected until 80 atmospheres are reached. The rectification of the reaction mixture results

46 g = 22% I.
123 g = 58% II
8.5 g = 4% homolog η = 319 g = 9% III
8.5 g = 4% homologue η > 4

b) As indicated in Example 8, 64.4 g of I and 148 g of II are heated to 250 ° C. for 4 hours and rectified. The following are obtained:

46 g = 22% I.

104 g = 49% II (+ homologue η = 2) 16 g = 7% homologue η = 3 2Ig = 10% III
19 g = 9% homologue η> 4

c) As stated in Example 8, 64.4 g of I and 148 g of II are ^{heated to 280 °} C. for 4 hours and rectified. The following are obtained:

12 g = 6% I.

37 g = 17% II (+ homologue η = 2) 23 g = 11% homologue η = 3 28 g = 13% III

19 g = _90/0 homologue η = 5 15 g = 7% homologue η = 6 61 g = 29% homologue η> 6

^{d) 64.4 g of I are heated to 100 °} C. for 4 hours with 148 g of II in a one-liter stainless steel autoclave without a glass vessel. Before this, 80 atmospheres of nitrogen are injected. After the reaction, the mixture is filtered and rectified with exclusion of moisture. The following are obtained:

32 g = 15% I (+ homologue η = 1 + hexa-

methylcyclotrisiloxane) 16 g = 8% II (+ homologue η = 2) 12 g = 6% homologue η = 3 12 g = 6% III

12 g = 6% homologue η - 5 g = 57% homologue η> 5

Claims (5)

PATENT CLAIMS: 1. Process for the preparation of 1,9-dihalodecaorganopentasiloxanes the general formula R " X-Si
R ' R "' - O - Si
R "" - X wherein R 'to R "" = alkyl, aryl or alkenyl radicals and X = a halogen atom, through Reaction of diorganodihalosilanes of the general formula R'R "SiX2 with octaorganocyclotetrasiloxanes the general formula (R '"R" "SiO) 4, characterized in that the reaction is carried out in a glass vessel at elevated pressure and Temperatures between 200 and 35O ⁰ C carried out in the absence of a catalyst. 2. The method according to claim 1, characterized in that the reaction in a glass vessel is carried out, which is sealed against the autoclave atmosphere with the help of a capillary is. 3. Process according to claims 1 and 2, characterized in that the reaction is below is carried out at an initial pressure at room temperature of 10 to 200 atm. 4. The method according to claim 1 to 3, characterized in that the reaction is carried out under an initial pressure at room temperature of 80 to 160 atmospheres and a temperature of 300 ⁰ C within 4 hours. 5. The method of claim 1 to 3, characterized in that the reaction is carried out at 27O ⁰ C and separated the unreacted starting materials from the reaction product by distillation, and repeatedly used for reaction. ι 309 749/421 11.63