Chemistry

G. V. Odabashyan, V. A. Ponomarenko, Yu. N. Kovalev
and Corresponding Member of the Academy of Sciences of the USSR A. D. Petrov

Organosilicon Monomers with Fluorine-Containing Cyclobutyl Rings

Organosilicon polymers containing fluorinated cyclobutyl rings, according to literature data ((^{1-3})), possess a number of valuable properties. The method for synthesizing the monomers from which the indicated polymers are obtained consists in the condensation of tetra- and trifluorochloroethylenes with alkenylsilanes, proceeding under pressure for 24–36 hours ((^{1-4})). The reactions proceed according to the schemes:

[
\mathrm{CF_2{=}CFCl + CH_2{=}CHSiCl_3
\ \xrightarrow[\;24\ \text{hr}\;]{210^\circ}\
Cl_3Si\overline{CHCFClCF_2CH_2};}
]

[
\mathrm{CF_2{=}CF_2 + CH_2{=}CHSi(CH_3)Cl_2
\ \xrightarrow[\;36\ \text{hr}\;]{210^\circ}\
CH_3(Cl_2)Si\overline{CHCF_2CF_2CH_2}}
\quad \text{etc.}
]

In the present work another route was studied for the synthesis of organosilicon monomers containing fluorinated cyclobutyl rings, namely synthesis according to the schemes:

[
\mathrm{CH_2{=}CH{-}CH{=}CH_2 + CF_2{=}CF_2
\rightarrow CH_2{=}CH\overline{CHCF_2CF_2CH_2};}
\tag{I}
]

[
\mathrm{R_nCl_{3-n}SiH + CH_2{=}CH\overline{CHCF_2CF_2CH_2}
\xrightarrow{H_2PtCl_6}
R_nCl_{3-n}SiCH_2CH_2\overline{CHCF_2CF_2CH_2};}
\tag{II}
]

[
\mathrm{R = CH_3,\ C_2H_5,\ C_6H_5;\quad n = 0,\ 1,\ 2,\ 3.}
]

The condensation of butadiene with tetrafluoroethylene (scheme I) proceeds fairly readily. The yield of (\mathrm{CH_2{=}CH\overline{CHCF_2CF_2CH_2}}) in this case reaches 90% ((^5)). As can be seen from Table 1, all the silicon hydrides taken by us, in the presence of platino-

Table 1

hydrochloric acid add to vinyltetrafluorocyclobutane in high yields. We also succeeded, under relatively more severe conditions (in an autoclave at 130°), in adding dichlorosilane in the presence of chloroplatinic acid to two molecules of vinyltetrafluorocyclobutane and obtaining, as is seen from Table 1, the corresponding monomer in 46% yield.

Experimental Part

1. β-(2,2,3,3-Tetrafluorocyclobutylethyl)trichlorosilane
   (\mathrm{Cl_3SiCH_2CH_2\overparen{CHCF_2CF_2CH_2}}). Into a three-necked round-bottom flask of 250 ml capacity, equipped with a mechanical stirrer, reflux condenser, and dropping funnel, were placed 4 ml of vinyltetrafluorocyclobutane, 0.1 ml of a 0.1 (M) solution of (\mathrm{H_2PtCl_6\cdot 6H_2O}) in isopropyl alcohol, and 1 ml of (\mathrm{HSiCl_3}). The reaction mixture was heated on a water bath until the reaction began (~80°), then a mixture of (\mathrm{CH_2=CH\overparen{CHCF_2CF_2CH_2}}) with (\mathrm{HSiCl_3}) was gradually added (in all, 15.4 g (0.1 mole) of (\mathrm{CH_2=CH\overparen{CHCF_2CF_2CH_2}}) and 13.6 g (0.1 mole) of (\mathrm{HSiCl_3}) were taken for the reaction) at such a rate as to maintain the temperature at this level. After the addition of the reagents was complete, the reaction mixture was heated for a further 15 min on the water bath with vigorous stirring. From 27.5 g of the crude reaction-product mixture, distillation in vacuo gave 26.5 g (91%) of (\mathrm{Cl_3SiCH_2CH_2\overparen{CHCF_2CF_2CH_2}}), b.p. 103.5–104.0° (31 mm); (d_4^{20}) 1.4395; (n_D^{20}) 1.4160; found (MR_D) 50.48; calculated 50.31.

[
\begin{aligned}
&\text{Found, \%: } &&\mathrm{C}\ 25.11;\ 25.21;\quad \mathrm{H}\ 2.89;\ 3.02;\quad \mathrm{Cl}\ 36.56;\ 36.50\
&\mathrm{C_6H_7SiCl_3F_4.}\ \text{Calculated, \%: } &&\mathrm{C}\ 24.89;\quad \mathrm{H}\ 2.44;\quad \mathrm{Cl}\ 36.76
\end{aligned}
]

1. β-(2,2,3,3-Tetrafluorocyclobutylethyl)methyldichlorosilane
   (\mathrm{CH_3(Cl_2)SiCH_2CH_2\overparen{CHCF_2CF_2CH_2}}). From 29.5 g of the crude reaction-product mixture obtained under the conditions of experiment 1, distillation in vacuo gave 25.8 g (91%) of (\mathrm{CH_3(Cl_2)SiCH_2CH_2\overparen{CHCF_2CF_2CH_2}}), b.p. 105–105.5° (28.5 mm), (d_4^{20}) 1.3151; (n_D^{20}) 1.4120; found (MR_D) 50.93; calculated 50.68.

[
\begin{aligned}
&\text{Found, \%: } &&\mathrm{C}\ 31.38;\ 31.45;\quad \mathrm{H}\ 3.94;\ 3.86;\quad \mathrm{Cl}\ 26.07;\ 26.06\
&\mathrm{C_7H_{10}SiCl_2F_4.}\ \text{Calculated, \%: } &&\mathrm{C}\ 31.30;\quad \mathrm{H}\ 3.72;\quad \mathrm{Cl}\ 26.05
\end{aligned}
]

1. β-(2,2,3,3-Tetrafluorocyclobutylethyl)ethyldichlorosilane
   (\mathrm{C_2H_5(Cl_2)SiCH_2CH_2\overparen{CHCF_2CF_2CH_2}}). From 16 g of the crude reaction-product mixture obtained under the conditions of experiment 1, distillation in vacuo gave 13.9 g (82%) of (\mathrm{C_2H_5(Cl_2)SiCH_2CH_2\overparen{CHCF_2CF_2CH_2}}), b.p. 99° (11 mm), (d_4^{20}) 1.2834; (n_D^{20}) 1.4180; found (MR_D) 55.61; calculated 55.19.

[
\begin{aligned}
&\text{Found, \%: } &&\mathrm{C}\ 34.54;\ 34.44;\quad \mathrm{H}\ 4.79;\ 4.69;\quad \mathrm{Cl}\ 24.87;\ 24.68\
&\mathrm{C_8H_{12}SiCl_2F_4.}\ \text{Calculated, \%: } &&\mathrm{C}\ 33.92;\quad \mathrm{H}\ 4.26;\quad \mathrm{Cl}\ 25.00
\end{aligned}
]

1. β-(2,2,3,3-Tetrafluorocyclobutylethyl)methylethylchlorosilane
   (\mathrm{CH_3(C_2H_5)(Cl)SiCH_2CH_2\overparen{CHCF_2CF_2CH_2}}). From 25.7 g of the crude reaction-product mixture obtained under the conditions of experiment 1, distillation in vacuo gave 20.6 g (79%) of (\mathrm{CH_3(C_2H_5)(Cl)SiCH_2CH_2\overparen{CHCF_2CF_2CH_2}})

b.p. 96–96.5° (13.5 mm), (d_4^{20}) 1.1663; (n_D^{20}) 1.4102; found (MR_D) 55.84; calculated 55.56.

[
\mathrm{C_9H_{15}SiClF_4}.
\quad
\begin{array}{ll}
\text{Found, \%:} & \mathrm{C}\ 41.03;\ 41.05;\quad \mathrm{H}\ 5.68;\ 5.81;\quad \mathrm{Cl}\ 13.33;\ 12.79 \
\text{Calculated, \%:} & \mathrm{C}\ 41.10;\quad \mathrm{H}\ 5.75;\quad \mathrm{Cl}\ 13.47
\end{array}
]

1. β-(2,2,3,3-tetrafluorocyclobutylethyl)methyldiethylsilane (\mathrm{CH_3(C_2H_5)_2SiCH_2CH_2CHCF_2CF_2CH_2}). From 24.5 g of the crude mixture of reaction products obtained under the conditions of experiment 1, distillation under vacuum gave 18.3 g (72%) of (\mathrm{CH_3(C_2H_5)_2SiCH_2CH_2CHCF_2CF_2CH_2}), b.p. 86–86.5° (11 mm), (d_4^{20}) 1.0373; (n_D^{20}) 1.4070; found (MR_D) 60.84; calculated 60.94.

[
\mathrm{C_{11}H_{20}SiF_4}.
\quad
\begin{array}{ll}
\text{Found, \%:} & \mathrm{C}\ 52.01;\ 52.24;\quad \mathrm{H}\ 7.92;\ 7.79;\quad \mathrm{F}\ 29.69;\ 29.69 \
\text{Calculated, \%:} & \mathrm{C}\ 51.79;\quad \mathrm{H}\ 7.83;\quad \mathrm{F}\ 29.66
\end{array}
]

1. β-(2,2,3,3-tetrafluorocyclobutylethyl)phenyldichlorosilane (\mathrm{C_6H_5(Cl)_2SiCH_2CH_2CHCF_2CF_2CH_2}). From 11.3 g of the crude mixture of reaction products obtained under the conditions of experiment 1, distillation under vacuum gave 8.9 g (70%) of (\mathrm{C_6H_5(Cl)_2SiCH_2CH_2CHCF_2CF_2CH_2}), b.p. 119.5–120° (3.5 mm), (d_4^{20}) 1.3223; (n_D^{20}) 1.4836; found (MR_D) 70.90; calculated 70.35.

[
\mathrm{C_{12}H_{12}SiCl_2F_4}.
\quad
\begin{array}{ll}
\text{Found, \%:} & \mathrm{C}\ 44.55;\ 44.27;\quad \mathrm{H}\ 3.69;\ 3.92;\quad \mathrm{Cl}\ 21.90;\ 21.68 \
\text{Calculated, \%:} & \mathrm{C}\ 43.80;\quad \mathrm{H}\ 3.64;\quad \mathrm{Cl}\ 21.26
\end{array}
]

1. Bis-(β-2,2,3,3-tetrafluorocyclobutylethyl)dichlorosilane (\mathrm{Cl_2Si(CH_2CH_2CHCF_2CF_2CH_2)_2}). Into a sampling autoclave of stainless steel with a capacity of 200 ml, in a glass tube, was placed a mixture of 23.2 g (0.15 mole) of (\mathrm{CH_2{=}CHCHCF_2CF_2CH_2}), 7.5 g (0.075 mole) of (\mathrm{H_2SiCl_2}), and 0.3 ml of a 0.1 (M) solution of (\mathrm{H_2PtCl_2\cdot 6H_2O}) in isopropyl alcohol. The mixture was heated to 120°, at which a sharp temperature rise to 158° was observed. The pressure meanwhile remained unchanged, 5.5 atm. The reaction time was 2 hours. On unloading the autoclave, the residual pressure was 1 atm. From 25.6 g of the crude mixture of reaction products, distillation under vacuum gave 14.2 g (46%) of crystalline (\mathrm{Cl_2Si(CH_2CH_2CHCF_2CF_2CH_2)_2}), b.p. 125–126° (2.5 mm).

[
\mathrm{C_{12}H_{14}SiCl_2F_8}.
\quad
\begin{array}{ll}
\text{Found, \%:} & \mathrm{C}\ 35.17;\ 35.55;\quad \mathrm{H}\ 3.48;\ 3.57;\quad \mathrm{Cl}\ 17.10;\ 17.35 \
\text{Calculated, \%:} & \mathrm{C}\ 35.18;\quad \mathrm{H}\ 3.48;\quad \mathrm{Cl}\ 17.32
\end{array}
]

Institute of Organic Chemistry
named after N. D. Zelinsky
Academy of Sciences of the USSR

Received
7.XII.1960

CITED LITERATURE

1. L. W. Frost, U.S. pat. 2596967 (1952); Chem. Abstr., 47, 4365 (1953).
2. Brit. pat. 760201 (1956); Chem. Abstr., 51, 14796 (1957).
3. Brit. pat. 802358 (1958); Chem. Abstr., 52, 9100 (1959).
4. J. D. Park, J. D. Groves, J. R. Lacher, J. Org. Chem., 25, No. 9, 1628 (1960).
5. D. D. Goffman, P. L. Barrick et al., J. Am. Chem. Soc., 71, 490 (1948).