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CHEMISTRY
Corresponding Member of the Academy of Sciences of the USSR R. Kh. Freidlina, Tsao I, and E. Ts. Chukovskaya
INTERACTION OF HYDRIDOSILANES WITH ACRYLONITRILE IN THE PRESENCE OF IRON PENTACARBONYL AND NICKEL CHLORIDE
As was shown earlier \((^{1})\), hydridosilanes react with unsaturated compounds in the presence of iron pentacarbonyl with the formation of saturated and unsaturated compounds according to schemes (A) and (B):
\[ \mathrm{R'R''R'''SiH + CH_2 = CHR \to R'R''R'''SiCH_2CH_2R;} \tag{A} \]
\[ \mathrm{R'R''R'''SiH + CH_2 = CHR \to R'R''R'''SiCH = CHR,} \tag{B} \]
where \(\mathrm{R'R''R'''}\) are, respectively, alkyl, chlorine, ethoxy groups; \(\mathrm{R} =\) alkyl, \(\mathrm{OC_2H_5}\). The predominance of one or the other of these reactions depends on the nature of the silane and olefin, as well as on the reaction conditions.
In the present work we investigated the reaction between hydridosilanes and acrylonitrile in the presence of iron pentacarbonyl. Since 1956 a considerable number of works have been devoted to the reaction of hydridosilanes with acrylonitrile \((^{2-11})\). Organic bases, acid amides, platinum on carbon, chloroplatinic acid, and Raney nickel have been used as reaction catalysts. Peroxides cannot be used in this reaction, since they cause polymerization of acrylonitrile \((^{3})\).
Organic bases and acid amides catalyze only the reaction of trichlorosilane with acrylonitrile and are inactive in the reaction of methyldichlorosilane with acrylonitrile \((^{5-7})\). In the presence of platinum catalysts and Raney nickel, methyldichlorosilane reacts with acrylonitrile; however, a mixture of \(\alpha\)- and \(\beta\)-methyldichlorosilylpropionitriles is formed.
Nozakura and Konotsune \((^{2})\) showed that, under the influence of various catalysts, cyanoethylation of trichlorosilane proceeds in different directions. Thus, in glass tubes in the presence of catalytic amounts of pyridine, \(\beta\)-trichlorosilylpropionitrile is formed. Under the same conditions in an autoclave, \(\alpha\)-trichlorosilylpropionitrile is formed. This is connected with the formation in the autoclave of tetrapyridinenickel chloride (owing to reaction of trichlorosilane with the metal wall of the autoclave). Thus, if the cyanoethylation of trichlorosilane can be directed both toward the formation of \(\beta\)-trichlorosilylpropionitrile and toward the \(\alpha\)-isomer, then in the case of methyldichlorosilane, under all conditions studied up to the present, mixtures of the \(\alpha\)- and \(\beta\)-isomers are formed.
We have studied the interaction of methyldichlorosilane and triethylsilane with acrylonitrile. The reaction was carried out in a stainless-steel autoclave or in sealed glass ampoules at \(120\text{–}150^\circ\) in the absence of additives or in the presence of iron pentacarbonyl, nickel chloride, or a mixture of both additives; the results obtained are summarized in Table 1. As is seen from Table 1, in the absence of additives the reaction does not proceed (experiment 6); upon addition of nickel chloride alone the reaction likewise does not take place (experiments 7 and 10). Triethylsilane does not react with acrylonitrile in the presence of iron pentacarbonyl in an autoclave (experiment 13). Methyldichlorosilane does not react with acrylonitrile in the presence of iron pentacarbonyl in a sealed glass ...
Table 1
| Experiment no. | Silane | Molar ratio: silane : acrylonitrile | Reaction vessel | Additives | Temp., °C | Yield from theory, % |
|---|---|---|---|---|---|---|
| 1 | CH₃SiCl₂H | 2 : 1 | Autoclave of stainless steel * | Fe(CO)₅ (1 ml) | 140–150 | 0 |
| 2 | Same | 1 : 1 | Same | Fe(CO)₅ (1 ml) | 140–150 | 12 |
| 3 | Same | 1 : 2 | Same | Fe(CO)₅ (1 ml) | 140–150 | 39 |
| 4 | Same | 1 : 3 | Same | Fe(CO)₅ (1 ml) | 140–150 | 46 |
| 5 | Same | 1 : 5 | Same | Fe(CO)₅ (1 ml) | 140–150 | 42 |
| 6 | Same | 1 : 3 | Same | No additives | 140–150 | 0 |
| 7 | Same | 1 : 3 | Same | NiCl₂ (0.15 g) | 140–150 | 0 |
| 8 | Same | 1 : 3 | Same | Fe(CO)₅ (1 ml) NiCl₂ (0.15 g)+ |
120–130 | 60 |
| 9 | Same | 1 : 3 | Sealed glass ampoule ** | +Fe(CO)₅ (0.2 g) | 140–150 | 0 |
| 10 | Same | 1 : 3 | Same | NiCl₂ (0.1 g) | 140–150 | 0 |
| 11 | Same | 1 : 3 | Same | Fe(CO)₅ (0.2 ml) NiCl₂ (0.1 g) |
120–130 | 56 |
| 12 | (C₂H₅)₃SiH | 1 : 3 | Autoclave of stainless steel * | Fe(CO)₅ (1 ml)+ +NiCl₂ (0.15 g) |
120–130 | 73 |
| 13 | Same | 1 : 3 | Same | Fe(CO)₅ (1 ml) | 140–150 | 30 |
| 14 | CH₃SiCl₂H *** | 2 : 1 | Same | Fe(CO)₅ (1 ml) | 140–150 | 4 |
* The experiments were carried out in a half-liter rotating autoclave with charges of silane and acrylonitrile of 200–300 g, calculated for the mixture of reagents. Air was displaced from the autoclave with nitrogen, after which nitrogen was introduced into the autoclave to a pressure of 30 atm. The duration of heating in all experiments was 5 h.
* The experiments were carried out with charges of 17.2 g of silane and 24.3 g of acrylonitrile. The duration of heating was 5 h.
** The reaction was conducted in the presence of 150 ml of acetonitrile.
ampoule (experiment 9), but under the same conditions, when the experiments are carried out in an autoclave, formation of the adduct takes place, the yield of which increases with increasing excess of acrylonitrile (experiments 1–5). These data made it possible to assume that the reaction is effected under conditions in which, in addition to iron carbonyl, traces of salts of heavy metals are present in the mixture, formed on the walls of the autoclave under the action of chlorosilanes.
Indeed, in the simultaneous presence of small amounts of iron pentacarbonyl and nickel chloride, acrylonitrile adds both methyldichlorosilane and triethylsilane. The reactions proceed equally well both in the autoclave (experiments 8, 12) and in sealed ampoules (experiment 11). The addition leads to α-methyldichlorosilylpropionitrile (CH₃SiCl₂CH(CH₃)CN) in the case of methyldichlorosilane and to α-triethylsilylpropionitrile ((C₂H₅)₃SiCH(CH₃)CN) in the case of triethylsilane. Apparently, the action of the mixed catalyst found by us directs the reaction by an ionic mechanism. The following arguments can be given in favor of this view: a) the reaction proceeds only in the presence of an excess of acrylonitrile (experiments 4–5) or in the medium of another polar solvent, for example acetonitrile (experiment 14); b) the participation of nickel chloride is necessary; c) the formation of α-isomers is usually associated with the ionic course of the cyanoethylation reaction of hydrosilanes (⁹).
Experimental section
We give a description of experiments 8 and 12 and the evidence for the structure of the adducts obtained.
Reaction of methyldichlorosilane with acrylonitrile in the presence of Fe(CO)₅ and NiCl₂ (experiment 8). Into a half-liter rotating stainless-steel autoclave were placed 115 g (1 mol)
\( \mathrm{CH_3SiCl_2H} \), 160 g (3 mol) \( \mathrm{CH_2{=}CH{-}CN} \), 1 ml \( \mathrm{Fe(CO)_5} \), and 0.15 g \( \mathrm{NiCl_2} \). The air was displaced from the autoclave with nitrogen, after which nitrogen was introduced to a pressure of 30 atm. After 5 h of heating at \(120—130^\circ\), the reaction mixture was fractionated in vacuo. This gave 102 g (60% of theory) of \(\alpha\)-methyldichlorosilylpropionitrile (I), b.p. \(59—60^\circ\) at 1 mm; \(n_D^{20}\) 1.4490; \(d_4^{20}\) 1.1635. Found \(MR\) 38.74; for \(\mathrm{C_4H_7SiCl_2N}\) calculated 38.62. Found, %: Si 17.21, 16.88. Calculated, %: Si 16.71. By titration with 0.1 \(N\) NaOH found, %: Cl 42.49; 42.41. For \(\mathrm{C_4H_7SiCl_2N}\) calculated, %: Cl 43.17.
Proof of the structure of the adduct was carried out according to the known scheme \((^{2,4})\)
\[ \begin{gathered} \mathrm{CH_3SiCl_2CHCN} \ \xrightarrow{0.1N\,NaOH}\ \mathrm{CH_3Si{-}CHCN} + 2\mathrm{HCl}; \\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \big| \\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \mathrm{O} \\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \big| \\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \mathrm{O} \\ \big| \qquad\qquad\qquad\quad \big| \\ \mathrm{CH_3} \qquad\qquad\qquad \mathrm{CH_3} \end{gathered} \tag{1} \]
\[ \begin{gathered} \mathrm{CH_3SiCl_2CHCN} + 3\mathrm{CH_3MgJ} \rightarrow (\mathrm{CH_3})_3\mathrm{SiCHCN} + \mathrm{C_2H_5CCH_3}; \\ \big| \qquad\qquad\qquad\qquad \big| \qquad\qquad\qquad \| \\ \mathrm{CH_3} \qquad\qquad\qquad\ \mathrm{CH_3} \qquad\qquad \mathrm{O} \end{gathered} \tag{2} \]
\[ \begin{gathered} \mathrm{C_2H_5CCH_3} + \mathrm{NH_2NHC_6H_3(NO_2)_2} \rightarrow \mathrm{C_2H_5CCH_3} \\ \| \qquad\qquad\qquad\qquad\quad \| \\ \mathrm{O} \qquad\qquad\qquad\qquad \mathrm{N{-}NHC_6H_3(NO_2)_2}; \end{gathered} \tag{2′} \]
\[ \begin{gathered} \mathrm{CH_2SiCl_2CHCN} + 2\mathrm{CH_3MgJ} \rightarrow (\mathrm{CH_3})_3\mathrm{SiCHCN}; \\ \big| \qquad\qquad\qquad\qquad \big| \\ \mathrm{CH_3} \qquad\qquad\qquad\ \mathrm{CH_3} \end{gathered} \tag{3} \]
\[ \begin{gathered} (\mathrm{CH_3})_3\mathrm{SiCHCN} \xrightarrow{40\%\,KOH} (\mathrm{CH_3})_3\mathrm{SiOSi(CH_3)_3} + \mathrm{CH_3CH_2COOH}; \\ \big| \\ \mathrm{CH_3} \end{gathered} \tag{4} \]
(II)
\[ \begin{gathered} \mathrm{CH_3CH_2COOH} + \mathrm{NH_2NHC_6H_5} \rightarrow \mathrm{CH_3CH_2CONHNH} \\ \big| \\ \mathrm{C_6H_5} \end{gathered} \tag{4′} \]
Since, in carrying out reaction (2), no
\[
(\mathrm{CH_3})_3\mathrm{SiCH_2CH_2CCH_3}
\quad
\begin{matrix}
\\[-0.6em]
\|\\
\mathrm{O}
\end{matrix}
\]
was detected, and in carrying out reaction (4) no acid of the structure \((\mathrm{CH_3})_3\mathrm{SiCH_2CH_2COOH}\) was formed, even an admixture of \(\beta\)-methyldichlorosilylpropionitrile is absent.
In the Raman spectrum of trimethylsilylpropionitrile there is a frequency of 2212 cm\(^{-1}\), and in the infrared spectrum of this substance an absorption band at 2205 cm\(^{-1}\) \(\pm\) 10 cm\(^{-1}\), characteristic of \(\alpha\)-nitriles*.
Preparation of \(\alpha\)-trimethylsilylpropionitrile. From 16 g of (I), on methylation with a Grignard reagent prepared from 4.8 g Mg, 8.8 g (70% of theory) of \(\alpha\)-trimethylsilylpropionitrile (II) was obtained, b.p. \(71.5^\circ/20\) mm; \(n_D^{20}\) 1.4245; \(d_4^{20}\) 0.8303. Found \(MR\) 39.14; for \(\mathrm{C_6H_{13}SiN}\) calculated 39.09. Literature data \((^2)\): \(n_D^{25}\) 1.4232; \(d_4^{25}\) 0.8254.
Found, %: C 56.64; 56.55; H 10.47; 10.37; Si 22.08; 22.39
\(\mathrm{C_6H_{13}SiN}\). Calculated, %: C 56.63; H 10.30; Si 22.05
* The spectra were recorded and interpreted by L. A. Leites (Institute of Organic Chemistry, Academy of Sciences of the USSR), for which the authors express their sincere gratitude to her.
Upon methylation with an excess of Grignard reagent, in addition to product (II), methyl ethyl ketone was obtained, b.p. 80–82°, \(n_D^{20}\) 1.3885. Literature data \((^{12})\): b.p. 79.6°; \(n_D^{20}\) 1.38071 \((^{15,9})\).
The ketone was identified as the 2,4-dinitrophenylhydrazone, m.p. 115° (from alcohol). Found, %: N 23.26; 22.92. For \(\mathrm{C}_{10}\mathrm{H}_{12}\mathrm{O}_4\mathrm{N}_4\) calculated, %: N 22.21. Literature data \((^{12})\): m.p. 117°.
Alkaline hydrolysis of trimethylsilylpropionitrile. Substance (II) was boiled for 7 h with 45% KOH. As a result, the following substances were obtained: \((\mathrm{CH}_3)_3\mathrm{Si}-\mathrm{O}-\mathrm{Si}(\mathrm{CH}_3)_3\), b.p. 99°, \(n_D^{20}\) 1.3740; \(d_4^{20}\) 0.7656. Found \(MR\) 48.42; for \(\mathrm{C}_6\mathrm{H}_{18}\mathrm{Si}_2\mathrm{O}\) calculated 48.89. Literature data \((^{13})\): \(n_D^{20}\) 1.3792; \(d_4^{20}\) 0.7638.
\[ \begin{aligned} &\text{Found, \%: } &&\mathrm{C}\ 44.43;\ 44.31;\quad \mathrm{H}\ 11.37;\ 11.51\\ &\mathrm{C}_6\mathrm{H}_{18}\mathrm{Si}_2\mathrm{O}.\ \text{Calculated, \%: } &&\mathrm{C}\ 44.38;\quad \mathrm{H}\ 11.17 \end{aligned} \]
2. \(\mathrm{CH}_3\mathrm{CH}_2\mathrm{COOH}\), b.p. 141°, \(n_D^{20}\) 1.3871. Literature data \((^{12})\): b.p. 141°, \(n_D^{20}\) 1.3874. The acid was identified as the phenylhydrazide, m.p. 153–155° (from benzene). Found, %: N 16.68; 16.57. \(\mathrm{C}_9\mathrm{H}_{12}\mathrm{N}_2\mathrm{O}\) calculated, %: N 17.06. Literature data \((^{2})\): m.p. 155–156°.
Reaction of triethylsilane with acrylonitrile in the presence of \(\mathrm{Fe(CO)}_5\) and \(\mathrm{NiCl}_2\) (experiment 12). The experiment was carried out as in the case of methyldichlorosilane. From 87 g (0.75 mole) of triethylsilane, 132 g (2.5 moles) of acrylonitrile, 0.5 ml of \(\mathrm{Fe(CO)}_5\), and 0.2 g of \(\mathrm{NiCl}_2\), 92 g (73% of theory) of a substance was obtained, b.p. 97–98° at 8 mm. After redistillation \(n_D^{20}\) 1.4525; \(d_4^{20}\) 0.8634. Found \(MR\) 52.95; for \(\mathrm{C}_9\mathrm{H}_{19}\mathrm{SiN}\) calculated* 52.88.
\[ \begin{aligned} &\text{Found, \%: } &&\mathrm{C}\ 63.77;\ 63.49;\quad \mathrm{H}\ 11.38;\ 11.33;\quad \mathrm{Si}\ 16.83;\ 16.85\\ &\mathrm{C}_9\mathrm{H}_{19}\mathrm{SiN}.\ \text{Calculated, \%: } &&\mathrm{C}\ 63.85;\quad \mathrm{H}\ 11.31;\quad \mathrm{Si}\ 16.57 \end{aligned} \]
Upon alkaline hydrolysis, carried out analogously to that described above, hexaethyldisiloxane and propionic acid were obtained.
In the IR spectrum of this compound there is a band at \(2205 \pm 10\ \mathrm{cm}^{-1}\), characteristic of \(\alpha\)-nitriles.
Institute of Organoelement Compounds
Academy of Sciences of the USSR
Received
20 I 1960
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* The calculation was made using group increments proposed by V. F. Mironov and G. I. Nikishin \((^{14})\).