A. M. POLYAKOVA and N. A. CHUMAEVSKII

ON THE INTERACTION OF TETRAALKYLDIHYDRIDODISILOXANES WITH DIFUNCTIONAL UNSATURATED COMPOUNDS

(Presented by Academician I. V. Obreimov, 3 IX 1959)

As was shown earlier ($^{1}$), tetraalkyldihydridodisiloxanes

\[ \begin{array}{c} \mathrm{R}\qquad\ \ \mathrm{R}\\ \ \ | \qquad\ \ \ |\\ \mathrm{H}-\mathrm{Si}-\mathrm{O}-\mathrm{Si}-\mathrm{H};\quad \mathrm{R}=\mathrm{CH}_3,\ \mathrm{C}_2\mathrm{H}_5, \\ \ \ | \qquad\ \ \ |\\ \mathrm{R}\qquad\ \ \mathrm{R} \end{array} \]

in the presence of a catalyst—platinic hydrochloric acid—react with difunctional unsaturated compounds of the type:

\[ \mathrm{CH}_2=\mathrm{CH}(\mathrm{R})\mathrm{M}(\mathrm{R})\mathrm{CH}=\mathrm{CH}_2 \]

and

\[ \mathrm{CH}_2=\mathrm{CH}-\mathrm{CH}_2(\mathrm{R})\mathrm{M}(\mathrm{R})\mathrm{CH}_2-\mathrm{CH}=\mathrm{CH}_2 \]

where $\mathrm{M}=\mathrm{Si}$ and $\mathrm{Ge}$; $\mathrm{R}=\mathrm{CH}_3,\ \mathrm{C}_2\mathrm{H}_5,\ \mathrm{C}_6\mathrm{H}_5$, with formation of polymeric products consisting of units

\[ \left[ \begin{array}{c} \ \ | \qquad\ \ \ | \qquad\ \ \ |\\ -\mathrm{Si}-\mathrm{O}-\mathrm{Si}-(\mathrm{CH}_2)_2-\mathrm{M}-(\mathrm{CH}_2)_2- \\ \ \ | \qquad\ \ \ | \qquad\ \ \ | \end{array} \right] \]

or, respectively,

\[ \left[ \begin{array}{c} \ \ | \qquad\ \ \ | \qquad\ \ \ |\\ -\mathrm{Si}-\mathrm{O}-\mathrm{Si}-(\mathrm{CH}_2)_3-\mathrm{M}-(\mathrm{CH}_2)_3- \\ \ \ | \qquad\ \ \ | \qquad\ \ \ | \end{array} \right]. \]

The aim of the present work is to study the structure of the polymeric products obtained by the method of infrared spectroscopy.

The infrared absorption spectra of the polymers obtained by us make it possible to judge their structure (for comparison, spectra of the starting components were also recorded; Figs. 1, 2, 3, 4).

The reaction of disiloxanes with dialkenes may proceed with formation of linear or cyclic polymers. This can be detected from the corresponding characteristic frequencies of the infrared absorption bands of the terminal groups Si—H and C=C. For linear polymers formed at an equimolecular ratio of the components, the presence of a Si—H bond may be expected at one end of the macromolecular chain, and of a C=C bond at the other.

With an excess of disiloxane in the reaction mixture, Si—H bonds may be expected at the ends of the macromolecular chain, and with an excess of dialkene, C=C bonds. In the case of a cyclic structure these bonds should be absent. The IR absorption bands of the stretching vibrations of the Si—H group lie in the frequency region 2100–2300 cm$^{-1}$ ($^{2}$); they are intense and are readily detected when present in a compound. For the tetraalkyldihydridodisiloxanes investigated by us, the Si—H group corresponds to a frequency of 2125–2130 cm$^{-1}$ (Fig. 1, Table 1).

The stretching vibrations of the C=C bond correspond to IR absorption bands at 1600–1680 cm$^{-1}$. For the divinyl compounds investigated, the frequency of the C=C bond has the value 1595 cm$^{-1}$, and for the diallyl compounds, 1630 cm$^{-1}$ (Fig. 2, Table 2). The intensity of the absorption bands of the double bond is weak and depends to a considerable extent on the symmetry of the molecule; this may complicate their detection in polymers, especially if one also takes into account the circumstance that the intensity of these bands will also decrease with increasing molecular…

molecular weights of the polymers, since the number of double bonds per unit volume will decrease as the size of the molecules increases.

The IR absorption spectra of polymers obtained by the interaction of divinyl monomers with disiloxanes, such as the reaction products from the interaction of diethyldivinylsilane, respectively, with all three disiloxanes ($n = 5,6$), and the reaction product from the interaction of phenylmethyldivinylsilane with dimethyldiethyldisiloxane ($n = 4$) (with an equimolecular ratio of the components), indicate the absence of the Si—H bond. At the same time, the spectra of polymer samples formed in the interaction of diallyl monomers with disiloxanes, such as the product of the interaction of diethyldiallylsilane with tetraethyldisiloxane ($n = 4$), and the products of the interaction of dimethyldiallylgermane with dimethyldiethyldisiloxane ($n = 6$) and with tetraethyldisiloxane ($n = 2$) under the same conditions, indicate its presence (Fig. 3). In the spectra of these same products, reprecipitated with alcohol, the band of the Si—H bond is absent.

Table 1

Frequencies of tetraalkyldihydridedisiloxanes (in cm$^{-1}$)*

* Frequencies in the region 680—1300 cm$^{-1}$ are given for solutions in carbon tetrachloride.

With an excess of disiloxane in the reaction mixture with the divinyl monomer (tetraethyldisiloxane and phenylmethyldivinylsilane), a band of the Si—H bond is found in the IR spectrum. The same is also observed in the spectrum of the polymer obtained by the interaction of tetraethyldisiloxane with diallyl—

Table 2

Frequencies of dialkenes (in cm$^{-1}$)

allyl (Fig. 4). With an excess, respectively, of diethyldiallylsilane and dimethyldiallylsilane in the reaction mixture with tetramethyldisiloxane, the polymers formed contain, in agreement with the assumption, C=C bonds. It should be noted that the frequencies of the groups Si—H (2125—2130 cm$^{-1}$), Si—O—Si (1060—1065 cm$^{-1}$), Si—CH$_3$ (1250—1255 cm$^{-1}$), and Si—C$_2$H$_5$ (1235—1240 cm$^{-1}$) are practically the same for monomers and for polymers.

On the basis of the results obtained, the following conclusion may be drawn about the structure of the polymers: the interaction of divinyl monomers

Fig. 1. IR absorption spectra of tetraalkyldihydridedisiloxanes

Fig. 2. IR absorption spectra of dialkenes

with disiloxanes, in an equimolecular ratio, leads to the formation of cyclic polymers, whereas diallyl monomers under the same conditions form linear polymers.

The IR absorption spectra were recorded on double-beam infrared spectrophotometers operating on the principle of the phase comparison method.

with beam intensities* using LiF (2800–3000 cm\(^{-1}\)) and NaCl (680–3000 cm\(^{-1}\)) prisms. With the LiF prism in the region of 3000 cm\(^{-1}\), the spectral slit width was 6 cm\(^{-1}\), and in the region of 1000 cm\(^{-1}\) with the NaCl prism the spectral slit width was 10 cm\(^{-1}\).

The substances were recorded as a layer between two salt windows**, and also in cells of constant thickness (0.016 and 0.05 mm).

Fig. 3. IR absorption spectra of the interaction products (with an equimolar ratio of the components)

In conclusion, we consider it a pleasant duty to thank Corresponding Member of the Academy of Sciences of the USSR V. V. Korshak and Academician I. V. Obreimov for their interest in the work, V. M. Vdovin and V. F. Mironov for carrying out the syntheses, and E. A. Dimitrieva and R. A. Isaev for valuable assistance in recording the IR spectra.

Received
3 IX 1959

CITED LITERATURE

1. V. V. Korshak, A. M. Polyakova et al., DAN, 128, 960 (1959).
2. L. Bellamy, Infrared Spectra of Molecules. IL, 1957, p. 394.

Fig. 4. IR absorption spectra of the interaction products (with an excess of disiloxane and dialkene)

* This recording method was developed in the optical laboratory by V. I. Dianov-Klokov.

** Spectra for which the layer thickness is not indicated were recorded between two salt windows.