1. Birchall J. M., Phorpe D. H. J. Chem. Soc., 2898 (1966)
2. A. A. Akhrem, A. M. Kuznetsova. Thin-Layer Chromatography. Moscow–Leningrad, “Nauka,” 1965.
3. Houben–Weyl. Methods of Organic Chemistry. Moscow, “Nauka,” 1963.

REACTION OF 4-HYDROXYDIPHENYLAMINE WITH VINYL ACETATE

E. E. Sirotkina, R. M. Kogan

The study of the reaction of vinyl ethers with aromatic compounds having two active groups—hydroxyl and amino groups—is of interest for obtaining vinyl monomers and polymers. When aromatic amino alcohols with a hydroxyl group in the side chain were used, cyclic adducts were synthesized in good yield instead of the expected alkenyl ethers /1/. Vinyl ethers of aminophenols and hydroxydiphenylamines obtained by Reppe vinylation have been described; in this case only the hydroxyl group proved to be reactive /2/.

In the present work, the behavior of 4-hydroxydiphenylamine in a vinyl-exchange reaction with vinyl acetate in the presence of mercury salts and sulfuric acid was studied. The amount of amino groups that had reacted was determined by the nitrosation method /3/; conversion of oxy groups was calculated as the difference between the total conversion of vinyl acetate and the amount of amino groups that had reacted.

As is evident from the data given in Table 1, the rate of reaction of the \(>NH\) and \(-OH\) groups depends on the ratio of the starting reagents, with the amino group being the most active. The \(N\)-vinyl group polymerizes immediately under the reaction conditions, whereas the vinyloxy group undergoes no further transformations.

Introduction of an electron-donor oxy group into the para position leads to redistribution of the electron density in the amine molecule /4/, which is accompanied by an increase in the negative charge on the nitrogen atom. This, apparently, explains the preferential pervinylation of 4-hydroxydiphenylamine at the amino group.

At an amine:vinyl acetate ratio of 1:1, the reaction products are \(N\)-vinyl oligomers containing unsubstituted oxy groups; with an excess of vinyl acetate relative to

Table I

Effect of the ratio of starting reagents on the reaction of vinyl acetate with 4-hydroxydiphenylamine.

Notes.
1. Amount of 4-hydroxydiphenylamine: 2,0 mol/L.
2. Reaction temperature: 20°C.
3. Amount of mercury acetate: 1% of the weight of the amine.
4. Ratio between mercury acetate and sulfuric acid: 1:6 mol/mol.
5. Amount of water: 0,2 mol/L.

* Calculated for one labile hydrogen atom.

amine greater than two, the amino and oxy groups fully enter into the reaction. Thus, by varying the ratios of the starting reagents, it is possible to synthesize \(N\)-vinyl oligomers of diphenylamine containing a definite number of oxy and vinyloxy groups.

The structure of the oligomers depends in many respects on the temperature conditions of the reaction. As is evident from the data presented in Table 2, when the temperature is lowered to \(-20^\circ\mathrm{C}\), the number of reacted amino groups decreases while the conversion of oxy groups simultaneously increases, which is in good agreement with literature data on the greater activity of phenols compared with amines in the transvinylation reaction at low temperatures / 5 /.

Table 2

Effect of reaction temperature on the interaction of vinyl acetate and 4-hydroxydiphenylamine

Note. 1. Ratio of starting reagents 1:1.
2. Reaction time 2 hours.
3. Amount of mercury acetate 1% by weight of the amine.
4. Ratio of mercury acetate to sulfuric acid 1:4.

Experimental part

Into a three-necked thermostated flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, at a temperature of \(30^\circ\mathrm{C}\), are charged 45 ml of acetone, 9.25 g of 4-hydroxydiphenylamine, 6 ml of freshly distilled vinyl acetate, 0.09 g of mercury acetate, and 0.085 ml of sulfuric acid (\(d = 1.84\ \mathrm{g/ml}\)). The course of the reaction is monitored by the acetic acid evolved; after its evolution ceases, the reaction mixture is poured into 500–600 ml of water. The precipitated polymer is filtered off. Yield 7 g.

(69% of theoretical). Molecular weight 1570 (cryoscopy). Melting point 115–127°C.

In the IR spectrum of the polymer (IKS-14a, Vaseline oil), absorption bands in the region 3400–3600 cm\(^{-1}\), characteristic of the secondary amino group and hydroxyl group, are absent; absorption bands appear in the regions 1625 cm\(^{-1}\), 995 cm\(^{-1}\), corresponding to absorption by the terminal vinyl group, which confirms the structure of poly-\(N\)-(4-vinyloxy)-vinyldiphenylamine.

The polymer is a dark-cherry-colored powder, readily soluble in ketones, dimethylformamide, and aqueous alkali solutions.

References

1. W. H. Watanabe. J. Amer. Chem. Soc., 79, 2833 (1957).
2. M. F. Shostakovskii. ZhOKh, 31, 1237 (1961).
3. R. P. Lastovskii, Yu. M. Vantsein. Technical Analysis in the Production of Intermediates and Dyes. Moscow, Goskhimizdat, 1958, p. 173.
4. S. P. Mushtakova, N. S. Frumkina, L. A. Gribov. ZhAKh, 26, 430 (1971).
5. R. Adelman. J. Amer. Chem. Soc., 75, 2678 (1953).

SILICATE FORMATION DURING THE MELTING OF GLASS OF DIOPSIDE COMPOSITION

P. G. Usov, V. I. Vereshchagin, E. L. Tsimbalyuk

Recently, intensive work has been carried out in the field of obtaining sitals with good dielectric characteristics. The most promising in this respect are sitals with a diopside-like crystalline phase. Studies by a number of authors have shown that such sitals possess not only good mechanical and chemical characteristics /1/, but also fairly good dielectric properties /2/. In our earlier work /3/ it was shown that crystallization of glasses of diopside compositions proceeds readily and without formation of by-products only on the basis of the natural mineral tremolite.

Tremolite \(Ca_2Mg_5[Si_8O_{22}](OH)_2\) is a typical representative of amphibole minerals, whose structure is characterized by infinite ribbons \([Si_4O_{11}]_\infty\), which are doubled pyroxene chains \([SiO_3]_\infty\). The synthesis of diopside from tremolite occurs