CHEMISTRY

V. F. MIRONOV, A. L. KRAVCHENKO

A NEW METHOD FOR OBTAINING ALKYLDICHLOROGERMANES AND ALKYLTRICHLOROGERMANES

(Presented by Academician B. A. Kazanskii, 13 IV 1964)

Whereas alkyldichlorosilanes \((\mathrm{RCl_2SiH})\) can readily be obtained and, on their basis, diverse methods for the synthesis of various organosilicon compounds are being widely developed, alkyldichlorogermanes \((\mathrm{RCl_2GeH})\) still remain an unstudied and practically inaccessible class of compounds. The only known route to the preparation of these compounds consists in replacing the hydrogen atoms in \(\mathrm{RGeH_3}\) by one reagent or another \({}^{(1-3)}\). This method requires the availability of scarcely accessible \(\mathrm{RGeH_3}\) and complicated apparatus for the gaseous lower members of the homologous series.

An attempt to alkylate \(\mathrm{HGeCl_3}\) with Grignard or organolithium reagents, both according to the literature and according to our data, does not lead to success \({}^{(4-7)}\). In these cases exclusively polymeric products of the composition

\[ \left[ \begin{array}{c} \mathrm{R}\\ |\\ -\mathrm{Ge}-\\ |\\ \mathrm{R} \end{array} \right]_x \]

are formed. Therefore it was decided to use other organometallic compounds for this purpose.

We found \({}^{[8]}\) that, when trichlorogermane containing \(\sim 30\%\ \mathrm{GeCl_4}\) is mixed with tetramethyltin, an exothermic reaction occurs, leading to a rather complex mixture of substances, from which the following compounds were isolated:

\[ (\mathrm{CH_3})_4\mathrm{Sn} \xrightarrow[\ ]{\mathrm{HGeCl_3+GeCl_4}} \mathrm{CH_4}\ (\sim 30\%) + \mathrm{CH_3GeCl_2H}\ (\sim 43\%)^{*} + \]
\[ +\, \mathrm{CH_3GeCl_3}\ (\sim 25\%); + (\mathrm{CH_3})_2\mathrm{SnCl_2}\ (26\%); \]
\[ (\mathrm{CH_3})_3\mathrm{SnCl}\ (\sim 57\%). \tag{1} \]

However, if this reaction is carried out with etherate of \(\mathrm{HGeCl_3}\) \({}^{[9]}\), only two compounds are formed:

\[ (\mathrm{CH_3})_4\mathrm{Sn} + \mathrm{HGeCl_3} \xrightarrow{\text{ether}} \mathrm{HGeCl_2CH_2CH_3}\ (80\%) + (\mathrm{CH_3})_3\mathrm{SnCl}\ (70\%). \]

Other alkyldichlorogermanes can be obtained in an analogous way. However, in these cases, along with \(\mathrm{RCl_2GeH}\), appreciable amounts of \(\mathrm{RGeCl_3}\) are formed and, in addition, hydrogen and the corresponding hydrocarbon are evolved:

\[ (\mathrm{C_2H_5})_4\mathrm{Sn} + \mathrm{HGeCl_3} \xrightarrow{\text{ether}} \mathrm{HGeCl_2C_2H_5}\ (45\%) + \mathrm{C_2H_5GeCl_3}\ (31\%) + \]
\[ +\,(\mathrm{C_2H_5})_3\mathrm{SnCl} + \mathrm{H_2} + \mathrm{C_2H_6}. \]

\[ (\mathrm{C_6H_5})_4\mathrm{Sn} + \mathrm{HGeCl_3} \xrightarrow{\text{ether}} \mathrm{HGeCl_2C_6H_5}\ (\sim 5\%) + \mathrm{C_6H_5GeCl_3}\ (45\%). \]

Replacement of tetraethyltin by tetraethyllead also leads to the formation of these same compounds, in somewhat different ratios:

\[ (\mathrm{C_2H_5})_4\mathrm{Pb} + \mathrm{HGeCl_3} \rightarrow \mathrm{HCl_2GeC_2H_5}\ (60\%) + \mathrm{C_2H_5GeCl_3}\ (\sim 20\%). \]

The structure of the obtained \(\mathrm{CH_3HGeCl_2}\), in addition to elemental analysis and spectra, is proved by its ability to add to ethylene and by further

* Here and below, yields for germanium and tin compounds are given, respectively, calculated on the germanium- or tin-containing starting component of the reaction.

into the known ethyltrimethylgermane:

\[ \mathrm{CH_3GeCl_2H \xrightarrow{CH_2{=}CH_2} C_2H_5GeCH_3Cl_2 \xrightarrow{CH_3MgX} C_2H_5Ge(CH_3)_3.} \]

It is also curious to note that, although \(\mathrm{HGeCl_3}\) cannot be alkylated with a Grignard reagent, under these conditions \(\mathrm{RGeHCl_2}\) are converted in good yields into the corresponding trialkylgermanes:

\[ \mathrm{C_2H_5HGeCl_2 \xrightarrow{CH_3MgBr} (C_2H_5)GeH(CH_3)_2 \quad (74\%).} \]

It could have been assumed that part of the substances formed in reaction (I) (for example, \(\mathrm{CH_3GeCl_3}\)) owed their origin to \(\mathrm{GeCl_4}\), always present in \(\mathrm{HGeCl_3}\) in an amount of about 30%. But it turned out that tetrachlorogermane does not react with tetramethyltin even on boiling*. At the same time tetraethyllead reacts with \(\mathrm{GeCl_4}\) with formation of ethyltrichlorogermane:

Fig. 1

Fig. 2

\[ \mathrm{(C_2H_5)_4Pb + GeCl_4 \rightarrow (C_2H_5)_3PbCl + C_2H_5GeCl_3 \quad (90\%).} \]

Taking into account the availability of \(\mathrm{(C_2H_5)_4Pb}\), this method of preparing ethyltrichlorogermane may prove to be one of the best.

Experimental Part

Methyldichlorogermane \(\mathrm{CH_3Cl_2GeH}\) (I). A. To 60 g of \(\mathrm{(CH_3)_4Sn}\), with stirring, etherate of \(\mathrm{HGeCl_3}\), prepared \(^{(9)}\) from 70 g of crude \(\mathrm{HGeCl_3}\), was added dropwise. The mixture boiled during this operation. After standing for an hour, distillation on a column gave 40 g of I, yield 80%, b.p. \(101.5^\circ\) (750 mm); \(n_D^{20}\) 1.4701, \(d_4^{20}\) 1.6356, \(MR_D\) 27.21; \(MR_D\) calculated 27.34; IR spectrum, see Fig. 1.

Found, %: C 7.86, 8.15; H 2.68, 2.69; Cl 43.90, 44.30; Ge 45.60, 45.30
\(\mathrm{CH_4GeCl_2}\). Calculated, %: C 7.53; H 2.53; Cl 44.44; Ge 45.51

Raman spectrum of I \((\Delta\nu,\ \mathrm{cm^{-1}})\):

150 (3 sh); 179 (3 sh); 191 (1); 396 (10 sh); 430 (0); 571 (1 sh); 625 (5 sh); 670 (2 sh); 707 (2 sh); 1168 (1); 1240 (1); 1261 (1); 1355 (1); 1410 (1 sh); 2132 (6 sh); 2925 (10); 3005 (3 sh).

In addition, 45 g of \(\mathrm{(CH_3)_3SnCl}\) was isolated, b.p. \(152\text{–}153^\circ\) (755 mm); m.p. \(34^\circ\). Yield 67%. Literature data \(^{(10)}\): b.p. \(152\text{–}154^\circ\) (760 mm); m.p. \(37^\circ\). In the residue, 7 g with m.p. \(\sim 300^\circ\).

* A reaction is observed between \(\mathrm{GeBr_4}\) and \(\mathrm{R_4Sn}\), but it is not possible to isolate individual compounds in this case.

B. To 25 g of \((\mathrm{CH}_3)_4\mathrm{Sn}\) was added 30 g of \(\mathrm{HGeCl}_3\). This evolved 1200 ml of gas consisting of 90.5% \(\mathrm{CH}_4\) and 9.5% hydrogen. Fractionation on a column gave 16 g of \((\mathrm{CH}_3)_3\mathrm{SnCl}\), b.p. \(150^\circ\) (760); m.p. \(37^\circ\), yield 57%; 8 g of \((\mathrm{CH}_3)_2\mathrm{SnCl}_2\) with b.p. \(190^\circ\) (760); m.p. \(105\)—\(107^\circ\), yield 21.4%; and 15 g of a mixture (chromatographic and spectral analyses) of \(\mathrm{CH}_3\mathrm{GeCl}_3 + \mathrm{CH}_3\mathrm{GeHCl}_2\) with b.p. \(100\)—\(110^\circ\) (760), yield 55%.

Ethyldichloromethylgermane \(\mathrm{C}_2\mathrm{H}_6\mathrm{Cl}_2\mathrm{GeCH}_3\) (II). Through 10 g of I, while boiling, ethylene was passed for 6 h. Fractionation on a column gave 10.5 g of II, yield 90%, b.p. \(149^\circ\) (750 mm); \(n_D^{20}\) 1.4600; \(d_4^{20}\) 1.4381, \(MR_D\) 36.13; \(MR_D\) calculated 36.00; for the IR spectrum, see Fig. 2.

\[ \begin{aligned} &\mathrm{C}_3\mathrm{H}_8\mathrm{GeCl}_2.\quad \text{Found, \%: } \mathrm{Cl}\ 37.70,\ 37.65\\ &\text{Calculated, \%: } \mathrm{Cl}\ 37.80 \end{aligned} \]

Raman spectrum of II \((\Delta\nu,\ \mathrm{cm}^{-1})\):

152 (2); 185 (2sh); 306 (1); 351 (0); 384 (10); 400 (3sh); 578 (9sh); 633 (3); 979 (1sh); 1027 (1sh); 1120 (0); 1161 (1sh); 1235 (2sh); 1261 (0); 1306 (0); 1346 (0); 1426 (1); 1461 (1); 2877 (2); 2917 (10); 2929 (1); 2667 (1); 3004 (1sh).

Ethyltrimethylgermane \(\mathrm{C}_2\mathrm{H}_5\mathrm{Ge}(\mathrm{CH}_3)_3\) (III). To \(\mathrm{CH}_3\mathrm{MgCl}\), prepared from 3 g of magnesium, was added 7 g of II. After the usual treatments, 4 g of III was obtained, b.p. \(78^\circ\) (760 mm); \(n_D^{20}\) 1.4080; yield 74%. The Raman spectrum of III completely coincides with the literature spectrum \(^{(11)}\).

Fig. 3

Fig. 4

Ethyldichlorogermane \(\mathrm{C}_2\mathrm{H}_5\mathrm{GeHCl}_2\) (IV). A. To 80 g of \((\mathrm{C}_2\mathrm{H}_5)_4\mathrm{Sn}\) was added 95 g of \(\mathrm{HGeCl}_3\) in 150 ml of ether. Heating occurred, and 1700 ml of gas was evolved, consisting of 15% \(\mathrm{C}_2\mathrm{H}_6\) and 85% \(\mathrm{H}_2\). Fractionation on a column gave 30 g of IV with b.p. \(129.5^\circ\) (743); \(n_D^{20}\) 1.4750, \(d_4^{20}\) 1.5358; \(MR_D\) 31.82; \(MR_D\) calculated 31.98; yield 45%. For the IR spectrum, see Fig. 3.

\[ \begin{aligned} &\text{Found, \%: } \mathrm{C}\ 13.55,\ 13.92;\ \mathrm{H}\ 3.30,\ 3.46;\ \mathrm{Cl}\ 41.20,\ 41.18;\ \mathrm{Ge}\ 42.10,\ 42.00\\ &\mathrm{C}_2\mathrm{H}_6\mathrm{GeCl}_2.\quad \text{Calculated, \%: } \mathrm{C}\ 13.83;\ \mathrm{H}\ 3.48;\ \mathrm{Cl}\ 40.85;\ \mathrm{Ge}\ 41.82 \end{aligned} \]

Raman spectrum of IV \((\Delta\nu,\ \mathrm{cm}^{-1})\):

155 (3sh); 174 (1); 279 (1sh); 310 (1); 395 (10b); 409 (1split); 523 (0); 537 (0); 581 (6); 597 (6); 656 (1sh); 681 (0); 709 (1sh); 732 (0); 749 (1); 974 (1sh); 1030 (2); 1118 (0); 1180 (0); 1234 (4); 1290 (0); 1306 (0); 1384 (0); 1421 (0); 1461 (2); 2120 (7b); 2877 (3); 2918 (4sh); 2935 (3); 2968 (2sh).

In addition to IV, 25 g of \(\mathrm{C}_2\mathrm{H}_5\mathrm{GeCl}_3\) (V) was isolated with b.p. \(141^\circ\) (743); \(n_D^{20}\) 1.4740, \(d_4^{20}\) 1.6028; yield 31%, and 80 g of \((\mathrm{C}_2\mathrm{H}_5)_3\mathrm{SnCl}\) with b.p. \(210\)—\(212^\circ\), m.p. \(15^\circ\). The Raman spectrum of V completely coincides with the literature spectrum \(^{(12)}\).

B. To 60 g of $\mathrm{Pb(C_2H_5)_4}$, cooled to $0^\circ$, 65 g of $\mathrm{HGeCl_3}$ etherate was slowly added. Heating occurred and a precipitate of $\mathrm{ClPb(C_2H_5)_3}$ separated. The precipitated solid was filtered off, and the filtrate was distilled. This gave 25 g of IV with b.p. $130^\circ$ (747 mm), $n_D^{20}$ 1.4740, yield 80.5%, and 55 g of $\mathrm{Cl—Pb(C_2H_5)_3}$, yield 90%. The IV obtained contains up to 20% V (chromatogram).

Dimethylethylgermane $\mathrm{C_2H_5GeH(CH_3)_2}$ (VI). To 8 g of IV, with cooling, was added $\mathrm{CH_3MgCl}$, prepared from 3 g of Mg in ether. After the usual work-up, distillation on a column gave 4.5 g of VI with b.p. $62^\circ$ (755 mm); $n_D^{20}$ 1.4078; $d_4^{20}$ 1.0077; $MR_D$ 32.48; $MR_D$, calculated 32.26; yield 74%. For the IR spectrum see Fig. 4.

\[ \begin{array}{ll} \mathrm{C_4H_{12}Ge}. & \text{Found, \%: C 35.81, 36.26; H 8.90, 9.08; Ge 54.06} \\ & \text{Calculated, \%: C 36.20; H 9.12; Ge 54.69} \end{array} \]

Ethyltrichlorogermane $\mathrm{C_2H_5GeCl_3}$ (V). To 40 g of $(\mathrm{C_2H_5})_4\mathrm{Pb}$ was added 26.6 g of $\mathrm{GeCl_4}$. The warmed mixture was left overnight, then heated at $\sim 100^\circ$ for one hour, and V was distilled from it under vacuum. Repeated distillation on a column gave 24 g of V, yield 90%; b.p. $140^\circ$ (750 mm), $n_D^{20}$ 1.4743. The solid residue, 40 g, consists of $(\mathrm{C_2H_5})_3\mathrm{PbCl}$, yield 94%.

We express our gratitude to L. A. Leites for carrying out the spectral analysis.

Zelinsky Institute of Organic Chemistry
Academy of Sciences of the USSR

Received
13 IV 1964

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