The question of the tautomerism of isatin

Summary

• 1. By the action of bromomethyl and chloromethyl ethers of methyl, ethyl, and propyl alcohols on the sodium and silver derivatives of isatin, the corresponding isatin ethers have been prepared; isatin methoxymethyl ether of m.p. 90–91*, isatin ethoxymethyl ether m.p. 85–85*, and isatin propoxymethyl ether of m.p. 79–80*.

• 2. All the derivatives obtained were readily hydrolyzed.

• 3. The hydrolysis products of the methoxy-, ethoxy-, and propoxy-methyl ethers of isatin were istain (obtained in almost quantitative yield), formaldehyde, and the corresponding alcohols.

• 4. By the action on the sodium and silver derivatives of isatin of (α-bromo-α,α-diphenyl-p-tolyl)-triphenylmethane, of benzyl bromide and chloride, and of aα-bromo-p-xylene there were obtained diphenyl-(α,α,α-triphenyl-p-tolyl)-methylisatin of m.p. 250–252*, benzylisatin of m.p. 131*, and (p-tolylmethyl)-isatin of m.p. 141–142*.

• 5. Attempts to hydrolyze the substances of m.p. 131*, 141–142*, and 250–252* did not give satisfactory results; the substances were recovered unchanged. The question of their structures remains an open one.

• 6. When the methoxymethyl and ethoxymethyl derivatives of isatin are heated with methyl iodide or with benzyl bromide, high-melting produces are obtained.

• 7. Benzylisatin remains unchanged in presence of methyl iodide or of benzyl bromide.