Isatin
IUPAC name	1H-indole-2,3-dione
Identifiers
CAS number	[91-56-5]
SMILES	O=C1c2ccccc2NC1=O
InChI	1/C8H5NO2/c10-7-5-3-1-2-4-6(5)9-8(7)11/h1-4H,(H,9,10,11)
Properties
Molecular formula	C8H5NO2
Molar mass	147.1308 g/mol
Appearance	Orange-red solid
Melting point	200 °C, 473 K, 392 °F
Hazards
EU classification	Harmful (Xn)
R-phrases	R22 R36 R37 R38
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references

Isatin or 1H-indole-2,3-dione is an indole derivative. The compound was first obtained by Erdman^[1] and Laurent^[2] in 1841 as a product from the oxidation of Indigo dye by nitric acid and chromic acids. The compound is found in many plants.

Schiff bases of Isatin are investigated for their pharmaceutical properties .^[3]

It was observed that isatin forms a blue dye if it is mixed with sulfuric acid and crude benzene. The formation of the blue indophenin was long believed to be a reaction with benzene. Victor Meyer was able to isolate the substance responsible for this reaction from benzene. This new heterocyclic compound was thiophene.^[4]

Preparation

Isatin is commercially available. It may be prepared from cyclicizing the condensation product of chloral hydrate, aniline and hydroxylamine in sulfuric acid:^[5]

Isatins can be made from the corresponding indole in good yield by a mix of InCl₃ and IBX in a acetonitrile-water solution at 80 °C.^[6]

References

1. ^ Otto Linné Erdmann (1840). "Untersuchungen über den Indigo". Journal für Praktische Chemie 19, (1): 321–362. doi:10.1002/prac.18400190161. 
2. ^ Auguste Laurent (1840). "Recherches sur l'indigo". Ann. chim. phys. 3, (3): 393–434. 
3. ^ Synthesis of 3,3´-[methylenebis(3,1-phenylenenitrilo)]bis[1,3-dihydro]-2H-indol-2-one as a novel bis-Schiff base A. A. Jarrahpour, D. Khalili Molbank 2005, M437 Online Article
4. ^ Ward C. Sumpter (1944). "The Chemistry of Isatin". Chemical Reviews 34, (3): 393–434. doi:10.1021/cr60109a003. 
5. ^ C. S. Marvel and G. S. Hiers (1941). "Isatin". Org. Synth.; Coll. Vol. 1: 327. 
6. ^ Yadav, J. S. (2007). "Indium(III) Chloride/2-Iodoxybenzoic Acid: A Novel Reagent System for the Conversion of Indoles to Isatins". Synthesis 2007 (5): 693–696. doi:10.1055/s-2007-965930. 

Further reading

• Piyasena Hewawasam and Nicholas A. Meanwell (1994). "A general method for the synthesis of isatins". Tetrahedron Letters 35 (40): 7303–6. doi:10.1016/0040-4039(94)85299-5.