CHEMISTRY

M. M. KOTON and T. M. KISELEVA

ON THE SYNTHESIS OF POLYORGANOSTANNOXANES

(Presented by Academician A. N. Nesmeyanov, June 20, 1959)

In recent years interest has grown in organotin compounds, which have found broad practical application for the stabilization of chlorine-containing polymers. Recently, low-molecular-weight tin-containing polymers have begun to be used for these purposes (¹ ²). In view of the absence of literature data (apart from patents) on the synthesis of polyorganostannoxanes containing in the main chain the grouping ≡Sn—O—Sn≡, we undertook an investigation of the possibility of obtaining such tin-containing polymers. For this purpose we used the polycondensation reaction, previously successfully employed by Andrianov (³) and Henglein (⁴) for the synthesis of various polyorganostannosiloxanes.

We studied the reaction of diacetates of n- and iso-butyltin with tetraethoxytin, in which formation of the —Sn—O—Sn bond occurred through interaction of acetate and ethoxyl groups according to the equation:

[
\begin{gathered}
\begin{matrix}
& \mathrm{C_4H_9} & \
\mathrm{CH_3COO}—& \mathrm{Sn} &—\mathrm{OCOCH_3}\
& \mathrm{C_4H_9} &
\end{matrix}
+
\mathrm{C_2H_5}—\mathrm{O}—
\begin{matrix}
& \mathrm{OC_2H_5}\
& \mathrm{Sn} &—\mathrm{O}\cdot \mathrm{C_2H_5}\
& \mathrm{OC_2H_5}
\end{matrix}
\rightarrow \[6pt]
\rightarrow
\mathrm{CH_3COO}
\left[
\begin{matrix}
& \mathrm{C_4H_9} & & \mathrm{OC_2H_5}\
—& \mathrm{Sn}—\mathrm{O}—\mathrm{Sn}—&\
& \mathrm{C_4H_9} & & \mathrm{OC_2H_5}
\end{matrix}
\right]_n
\mathrm{OC_2H_5}
+
\mathrm{CH_3COOC_2H_5}
\end{gathered}
\tag{I}
]

Polymer (I) was isolated as a light-yellow powder with a softening temperature of 70–75° (in the case of ((iso\text{-}\mathrm{C_4H_9})_2\mathrm{Sn(OAc)_2})) or 60–70° (in the case of ((n\text{-}\mathrm{C_4H_9})_2\mathrm{Sn(OAc)_2})). The molecular weight of polymer (I) was 1890–1990 (for the tetramer, 1936). Thus, under the experimental conditions formation of a linear low-molecular-weight ((n=4)) polyorganostannoxane was observed. The polymer is hydrolyzed on heating with water, with elimination of ethoxyl and acetate groups, forming an insoluble, infusible compound (II) of composition:

[
\mathrm{HO}
\left[
\begin{matrix}
& \mathrm{C_4H_9}\
—& \mathrm{Sn}—\mathrm{O}—\mathrm{Sn}—\
& \mathrm{C_4H_9} & |\
& & \mathrm{O}
\end{matrix}
\right]_n
\mathrm{OH}
\tag{II}
]

Experimental Part

Dibutyltin diacetates were obtained from the corresponding dichlorides (⁴). Diisobutyltin diacetate is a liquid with b.p. 140–141° (10 mm).

[
\mathrm{C_{12}H_{24}O_4Sn.}
\qquad
\begin{array}{ll}
\text{Found, \%:} & \mathrm{Sn}\ 34.1\
\text{Calculated, \%:} & \mathrm{Sn}\ 33.9
\end{array}
]

Diacetate of di-($n$-butyl)tin—a liquid with b.p. 146–147° (10 mm), $n_D^{20}$ 1.4707.

[
\begin{aligned}
&\text{Found, \%: } &&\mathrm{C}\ 46.30;\ \mathrm{H}\ 7.19;\ \mathrm{Sn}\ 34.21\
&\mathrm{C}{12}\mathrm{H}\ 33.93}\mathrm{O}_{4}\mathrm{Sn}. \ \text{Calculated, \%: } &&\mathrm{C}\ 46.72;\ \mathrm{H}\ 6.81;\ \mathrm{Sn
\end{aligned}
]

Tetrastoxytin was obtained by the method of Meerwein and Bersin ($^{5}$).

Reaction of $(\mathrm{C}{2}\mathrm{H})}\mathrm{O{4}\mathrm{Sn}$ with $(n\text{-}\mathrm{C}}\mathrm{H{9})}\mathrm{Sn}(\mathrm{OCOCH{3})$ in molar ratios of 1 : 1. Heating on a glycerol bath at 140° for 28 hr in a stream of inert gas, with distillation of the ethyl acetate formed, of which 74.6% (of theory) was collected. Treatment of the polycondensation product with benzene gave an insoluble, infusible up to 250° crystalline precipitate containing 57.9–58.1% Sn. From the benzene solution a light-yellow polymer with a softening temperature of 70–75° was isolated. The molecular weight, determined by the cryoscopic method, was found to be 1890 (1936 calculated for the tetramer).

[
\begin{aligned}
&\text{Found, \%: } &&\mathrm{C}\ 30.02;\ \mathrm{H}\ 5.78;\ \mathrm{Sn}\ 50.41\
&\mathrm{C}{52}\mathrm{H}}\mathrm{O{15}\mathrm{Sn}\ 49.17}. \ \text{Calculated, \%: } &&\mathrm{C}\ 32.22;\ \mathrm{H}\ 6.19;\ \mathrm{Sn
\end{aligned}
]

The polymer is hydrolyzed on boiling with water, with formation of a white insoluble and infusible product.

[
\begin{aligned}
&\text{Found, \%: } &&\mathrm{Sn}\ 60.92\
&\mathrm{C}{32}\mathrm{H}}\mathrm{O{10}\mathrm{Sn}\ 60.63}. \ \text{Calculated, \%: } &&\mathrm{Sn
\end{aligned}
]

Reaction of $(\mathrm{C}{2}\mathrm{H})}\mathrm{O{4}\mathrm{Sn}$ and $(n\text{-}\mathrm{C}}\mathrm{H{9})}\mathrm{Sn}(\mathrm{OCOCH{3})}$—the conditions were the same as in the case of $(n\text{-}\mathrm{C{4}\mathrm{H}){2}\mathrm{Sn}(\mathrm{OCOCH}$. An insoluble and infusible precipitate was obtained, containing 56.71–57.2% Sn. From the benzene solution a light-yellow polymer with a softening temperature of 60–70° was isolated. Molecular weight of the polymer (cryoscopically) 1991.})_{2

[
\begin{aligned}
&\text{Found, \%: } &&\mathrm{Sn}\ 50.1\
&\mathrm{C}{52}\mathrm{H}}\mathrm{O{15}\mathrm{Sn}\ 49.17}. \ \text{Calculated, \%: } &&\mathrm{Sn
\end{aligned}
]

Institute of High-Molecular Compounds
Academy of Sciences of the USSR

Received
14 I 1959

REFERENCES CITED

1. G. Mack, E. Parker, Amer. pat. 2592926 (1952); C. A., 46, 11767 (1952); Amer. pat. 2683705 (1954); C. A., 1955, 7097.
2. J. Brydson, Plastics, 1957, 384.
3. K. A. Andrianov, T. N. Ganina, E. N. Khrustaleva, Izv. AN SSSR, OKhN, 1956, 798.
4. F. Henglein, R. Lang, L. Schmack, Makr. chim., 22, 103 (1957).
5. H. Meerwein, Th. Bersin, J. An. Chem., 476, 132 (1929).