Abstract
Full Text
CHEMISTRY
K. M. BERDICHEVSKAYA, V. S. CHUGUNOV,
Corresponding Member of the Academy of Sciences of the USSR A. D. PETROV
SYNTHESIS OF SOME FLUORINE-CONTAINING SILYLFERROCENES
Various investigators \(^{(1-5)}\) have already synthesized, from dilithioferrocene and various trialkyl-(aryl)-chlorosilanes, a series of bis-[trialkyl-(aryl)-silyl]ferrocenes according to the scheme
\[ \begin{gathered} \mathrm{Li}\text{-ferrocene-}\mathrm{Li} + 2R_3\mathrm{SiCl} \longrightarrow \mathrm{(R_3Si)\text{-}ferrocene\text{-}(SiR_3)} \end{gathered} \]
The starting trialkyl-(aryl)-chlorosilanes were usually obtained according to the scheme:
\[ \mathrm{Mg}+\mathrm{RCl}\rightarrow \mathrm{RMgCl},\qquad 3\mathrm{RMgCl}+\mathrm{SiCl}_4\rightarrow \mathrm{R}_3\mathrm{SiCl}+3\mathrm{MgCl}_2 \]
However, among the bis-[trialkyl-(aryl)-silyl]ferrocenes obtained, fluorinated derivatives of this series are still lacking.
In order to fill this gap, the present investigation was undertaken.
Since, upon metalation of ferrocene with lithium, di- and monosubstituted ferrocene derivatives are obtained, we expected that from tris-(\(\gamma\gamma\gamma\)-trifluoropropyl)-chlorosilane and ferrocenyl lithium we would obtain both compound I and compound II.
\[ \begin{gathered} \mathrm{Li}\text{-ferrocene-}\mathrm{Li} + \mathrm{ClSi(CH_2CH_2CF_3)_3} \longrightarrow \mathrm{(CF_3CH_2CH_2)_3Si\text{-}ferrocene\text{-}Si(CH_2CH_2CF_3)_3} \\ \text{(I)} \\ + \mathrm{ferrocene\text{-}Si(CH_2CH_2CF_3)_3} \\ \text{(II)} \end{gathered} \]
Indeed, by fractionation and recrystallization, compound I with m.p. \(155^\circ\) and compound II with m.p. \(105^\circ\) were obtained. However, as a small impurity it was also possible to isolate compound III, with m.p. \(141\text{—}142^\circ\), which did not contain iron and, according to analytical data, corresponded rather closely to hexa-(\(\gamma\gamma\gamma\)-trifluoropropyl)-disiloxane, described earlier \(^{(6)}\). Apparently this compound was formed according to the scheme:
\[ 2(\mathrm{CF_3CH_2CH_2})_3\mathrm{SiCl}+\mathrm{H_2O} \rightarrow 2\mathrm{HCl}+(\mathrm{CF_3CH_2CH_2})_3\mathrm{SiOSi}(\mathrm{CH_2CH_2CF_3})_3 \tag{III} \]
We synthesized for the first time bis-(tripropylsilyl)-ferrocene (VI), analogous to compound
\[ \mathrm{(CH_2CH_2CH_3)_3Si\text{-}ferrocene\text{-}Si(CH_2CH_2CH_3)_3} \tag{VI} \]
which proved to be a liquid with b.p. \(227\text{—}233^\circ\) at 1 mm.
From dimethyl-\(m\)-benzotrifluoridechlorosilane* and ferrocenyl lithium also
\[ \text{* Here and below, benzotrifluoride denotes the } m\text{-trifluoromethylphenyl residue.} \]
Compounds IV with m.p. 71° and V with m.p. 50° were obtained.
\[ \begin{array}{cc} \begin{array}{c} \mathrm{C_6H_4CF_3}\\ \mathrm{Si}\!\left(\mathrm{CH_3}\right)_2\\ \mathrm{Fe}\\ \mathrm{Si}\!\left(\mathrm{CH_3}\right)_2\\ \mathrm{C_6H_4CF_3}\\ \text{(IV)} \end{array} & \begin{array}{c} \mathrm{C_6H_4CF_3}\\ \mathrm{Si}\!\left(\mathrm{CH_3}\right)_2\\ \mathrm{Fe}\\ \text{(V)} \end{array} \end{array} \]
Dimethylphenylsilylferrocene, described in the literature and not containing a \(\mathrm{CF_3}\) group \((^7)\), has m.p. 83—84.5°.
Experimental Section
1. Dimethyl-m-benzotrifluoridechlorosilane. Into a three-necked flask equipped with a stirrer with a mercury seal, a dropping funnel, and a reflux condenser were charged 24 g (1 mole) of magnesium in 100 ml of absolute ether, and an ethereal solution of 225 g (1 mole) of m-bromobenzotrifluoride \((^8)\) and 142 g (1.1 mole) of dimethyldichlorosilane was added gradually. The reaction mixture was boiled for 6 hours, then filtered, and the filtrate was distilled. Forty-three grams of product distilling at 90—100°/15 mm, with chlorine content 13.4%, was isolated and used in subsequent syntheses.
II. Tris-(γγγ-trifluoropropyl)-chlorosilane was obtained from 133 g (1 mole) of γγγ-trifluorochloropropane, 24 g (1 mole) of magnesium, and 55 g (0.32 mole) of silicon tetrachloride, as described above. Fifty-eight grams of product with b.p. 80—120°/20 mm and chlorine content 12.9%* was isolated.
There is a report on the preparation of this compound in the patent literature \((^9)\), but no constants are given.
III. [Tris-(γγγ)-trifluoropropyl)-silyl]-ferrocene. Into an apparatus equipped as before were placed 18 g (0.1 mole) of ferrocene; to it was added an ethereal solution of 0.21 \(M\) n-butyllithium, and the mixture was stirred in a stream of dry oxygen-free nitrogen at room temperature for 3 days, with a break overnight.
Then 58 g (0.16 \(M\)) of tris-(γγγ-trifluoropropyl)-chlorosilane in 100 ml of absolute ether was added to the reaction mixture, and the mixture was stirred at room temperature for another 3 days. After this the reaction mass was treated with ice water; the organic layer was separated and dried over sodium sulfate.
By evaporating the excess ether, 3 g of unreacted ferrocene was isolated. Repeated crystallization of the residue from a benzene—petroleum ether—carbon disulfide mixture (2 : 2 : 1) gave 0.7 g of III with m.p. 141—142°, which showed no depression with the product obtained by other authors \((^6)\).
\[ \begin{aligned} &\text{Found, \%: } &&\mathrm{C}\ 31.6;\ \mathrm{H}\ 3.9;\ \mathrm{Si}\ 8.6;\ \mathrm{F}\ 50.0\\ &\mathrm{C_6H_8OSiF_6.}\ \text{Calculated, \%: } &&\mathrm{C}\ 33.0;\ \mathrm{H}\ 3.6;\ \mathrm{Si}\ 8.5;\ \mathrm{F}\ 52.2. \end{aligned} \]
The residue after crystallization was distilled in a stream of nitrogen. At 180—205°/12 mm, 7.5 g of crystals with m.p. 93—95° distilled over; after recrystallization from a benzene—petroleum ether (1 : 1) mixture and methanol, they had m.p. 105° (II).
\[ \begin{aligned} &\text{Found, \%: } &&\mathrm{C}\ 45.5;\ \mathrm{H}\ 4.4;\ \mathrm{Si}\ 6.2;\ \mathrm{Fe}\ 11.8;\ \mathrm{F}\ 30.5\\ &\mathrm{C_{19}H_{21}F_9SiFe.}\ \text{Calculated, \%: } &&\mathrm{C}\ 45.2;\ \mathrm{H}\ 4.17;\ \mathrm{Si}\ 5.5;\ \mathrm{Fe}\ 11.1;\ \mathrm{F}\ 33.9. \end{aligned} \]
IV. Bis-[tris-(γγγ-trifluoropropyl)-silyl]-ferrocene. The product was obtained by repeated crystallization of the residue after distil—
* N. L. Kopnova, V. S. Chugunov, A. L. Klebanskii (in press).
II from a benzene–petroleum ether and benzene–methanol mixture; yellow crystals with m.p. 155° were isolated.
\[ \begin{aligned} &\text{Found, \%: } \mathrm{C}\ 41.5;\ \mathrm{H}\ 4.1;\ \mathrm{Si}\ 7.6;\ \mathrm{F}\ 38.2;\ \mathrm{Fe}\ 6.9\\ &\mathrm{C}_{28}\mathrm{H}_{32}\mathrm{Si}_{2}\mathrm{F}_{18}\mathrm{Fe}.\quad \text{Calculated, \%: } \mathrm{C}\ 40.9;\ \mathrm{H}\ 3.9;\ \mathrm{Si}\ 6.8;\ \mathrm{F}\ 41.6;\ \mathrm{Fe}\ 6.8 \end{aligned} \]
V. Dimethyl-m-benzotrifluoride-silylferrocene. To 16 g (0.85 mole) of ferrocene was added 0.2 M ethereal solution of n-butyllithium. The reaction mixture was stirred for 4 days at room temperature. Then 71 g (0.29 mole) of dimethyl-m-benzotrifluoride-chlorosilane was added to the mixture in several portions until the alkaline reaction to phenolphthalein disappeared, and the mixture was stirred at room temperature for another 3 days. The reaction mass was decomposed with water and separated; the ether was evaporated in air, unreacted ferrocene was removed by steam distillation, and the residue was dried with sodium sulfate and distilled.
There were isolated 8 g of a dark oil with b.p. 205–232° at 17 mm, \(n_D^{20}\) 1.5350, and about 5 g of a crystallizing product distilling at 232–235° at 17–5 mm with decomposition.
By chromatography of the oil on alumina and repeated crystallization from petroleum ether, V was isolated with m.p. 50°.
\[ \begin{aligned} &\text{Found, \%: } \mathrm{C}\ 59.4;\ \mathrm{H}\ 5.3;\ \mathrm{Si}\ 7.8;\ \mathrm{Fe}\ 15.1;\ \mathrm{F}\ 12.15\\ &\mathrm{C}_{19}\mathrm{H}_{19}\mathrm{SiFeF}_{3}.\quad \text{Calculated, \%: } \mathrm{C}\ 58.8;\ \mathrm{H}\ 4.9;\ \mathrm{Si}\ 7.2;\ \mathrm{Fe}\ 14.4;\ \mathrm{F}\ 14.7 \end{aligned} \]
Bis-(dimethyl-m-benzotrifluoride-silyl)-ferrocene. From the fraction with b.p. 232–235° at 17–5 mm, by repeated crystallization from petroleum ether, IV was isolated with m.p. 70–71°. An additional amount of product with m.p. 71° was isolated from the mother liquor by chromatography on alumina.
\[ \begin{aligned} &\text{Found, \%: } \mathrm{C}\ 57.7;\ \mathrm{H}\ 5.1;\ \mathrm{Si}\ 9.6;\ \mathrm{Fe}\ 17.5;\ \mathrm{F}\ 10.7\\ &\mathrm{C}_{28}\mathrm{H}_{28}\mathrm{Si}_{2}\mathrm{FeF}_{6}.\quad \text{Calculated, \%: } \mathrm{C}\ 56.9;\ \mathrm{H}\ 4.7;\ \mathrm{Si}\ 9.5;\ \mathrm{Fe}\ 19.3;\ \mathrm{F}\ 10.5 \end{aligned} \]
VI. Bis-(tripropylsilyl)-ferrocene. To 13 g (0.07 mole) of ferrocene were added 0.14 mole of an ethereal solution of n-butyllithium and 60 g of THF. The mixture was stirred for 48 hours in a stream of dry nitrogen. Then 35 g of tripropylbromosilane was added (and after 10 hours another 16 g), after which the mixture was stirred for another 40 hours at room temperature and boiled for 3 hours. Decomposition was carried out with ice water; the ether layer was dried over \(\mathrm{Na}_2\mathrm{SO}_4\). Fifteen grams of bis-(tripropylsilyl)-ferrocene was obtained, b.p. 227–233° at 1 mm, \(n_D^{20}\) 1.5203, \(d_4^{20}\) 1.0214.
\[ \begin{aligned} &\text{Found, \%: } \mathrm{C}\ 67.2;\ \mathrm{H}\ 10.9;\ \mathrm{Si}\ 11.9;\ \mathrm{Fe}\ 12.2\\ &\mathrm{C}_{28}\mathrm{H}_{50}\mathrm{Si}_{2}\mathrm{Fe}.\quad \text{Calculated, \%: } \mathrm{C}\ 67.3;\ \mathrm{H}\ 10.04;\ \mathrm{Si}\ 11.2;\ \mathrm{Fe}\ 11.2 \end{aligned} \]
State Institute of Applied Chemistry
Received
29 V 1963
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