5104. Isatin

Nomenclature

CAS number: 91-56-5
1H-Indole-2,3-dione; 2,3-indolinedione; 2,3-diketoindoline; 2,3-dioxoindoline.
C8H5NO2; mol wt 147.13.
C 65.31%, H 3.43%, N 9.52%, O 21.75%.

Description and references

May be obtained by oxidation of indigo or of oxygenated indoles such as indoxyl, oxindole, or dioxindole: Erdmann, J. Prakt. Chem. [1] 24, 1 (1841); Laurent, ibid. 25, 430 (1842); DE 229815 in Frdl. 10, 353 (1910); JP 152932 (1942 to ICI); C.A. 44, 1544d (1950). Synthesis: Sandmeyer, Helv. Chim. Acta 2, 234 (1919); GB 128122 in C.A. 13, 2375 (1919); Marvel, Hiers, Org. Synth. coll. vol. I (2nd ed., 1941) p 327; Wibaut, Gerling, Rec. Trav. Chim. 50, 41 (1931); Neunhoeffer, Lehmann, Ber. 94, 2960 (1961); Ziegler et al., Monatsh. Chem. 94, 453 (1963). May be isolated from the urine of rabbits that are fed o-nitrophenylglyoxylic acid: Bohm, Z. Physiol. Chem. 265, 210 (1940). Pharmacology: Singh, Indian Vet. J. 48, 672 (1971). Reviews: Heller, Ueber Isatin, Isatyd, Dioxindol und Indophenin (F. Enke, Stuttgart, 1931); Sumpter, Chem. Rev. 34, 393 (1944). Discussion of chemistry of isatin: Morton, Chemistry of Heterocyclic Compounds (New York, 1946) pp 126-132.

Chemical structure

Properties

Orange-colored monoclinic prisms. mp 203.5° (partial sublimation). Absorption spectrum: Hartley, Dobbie, J. Chem. Soc. 75, 647, 656. Freely sol in boiling alcohol; sol in ether and in boiling water with reddish-brown color; sol in alkali hydroxide solns with a violet color becoming yellow on standing. The alc soln imparts a persistent, disagreeable odor to the human skin. Extremely weak base, forms a crystalline perchlorate, C8H5NO2.HClO4.2H2O.

Use

Manuf vat dyes. In analytical chemistry as a reagent for cuprous ions, mercaptans, thiophene, and indican.