Isatin

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Structural formula
Isatin structural formula
General
Surname Isatin
other names
  • 2,3-indolinedione
  • 2,3-dioxoindoline
  • ISATIN ( INCI )
Molecular formula C 8 H 5 NO 2
Brief description

orange-red solid

External identifiers / databases
CAS number 91-56-5
EC number 202-077-8
ECHA InfoCard 100,001,889
PubChem 7054
ChemSpider 6787
DrugBank DB02095
Wikidata Q421348
properties
Molar mass 147.13 g · mol -1
Physical state

firmly

Melting point

199-204 ° C

solubility
  • poorly soluble in water (2 g l −1 at 20 ° C)
  • soluble in benzene
safety instructions
GHS labeling of hazardous substances
no GHS pictograms
H and P phrases H: no H-phrases
P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Isatin is an organic compound and a derivative of indole .

history

Isatin was first isolated by the French chemist Auguste Laurent , and Adolf von Baeyer did not succeed in total synthesis until 1878 . In 1880 he developed a synthesis route based on o-nitro cinnamic acid , in 1883 he patented a synthesis route from 2-nitrobenzaldehyde . As a result, indigo no longer had to be laboriously extracted from plants.

Manufacturing

In the past, isatin could only be obtained from indigo. Today it is made from benzoic acid derivatives or using the Sandmeyer process.

Synthesis of isatin

Aniline ( 1 ) is converted to α-isonitrosoacetanilide (hydroxyaminoacetanilide, 2 ) in the presence of chloral hydrate and hydroxylamine , which form the corresponding oxime . By the action of conc. Sulfuric acid cyclizes this to isatin-3-imide ( 3 ) and is then finally saponified to isatin ( 4 ).

properties

Isatin is moderately soluble in cold water and more soluble in hot water with orange color. Isatin with a red-orange color is readily soluble in ethanol . If you add a little sodium carbonate to the heated aqueous solution (alkaline effect), the color changes to red-violet due to deprotonation. When sodium dithionite is added to the solution, it becomes light yellow to colorless. A reduction to the leuco form takes place, the corresponding diol is formed, which can be oxidized again to the dione by a suitable oxidizing agent (e.g. also atmospheric oxygen). So this process is an example of vat dyeing . The decomposition temperature is> 193 ° C, the flash point is 200 ° C.

use

Isatin and its derivatives are important starting compounds for indigo (the dye in blue jeans ) and indigo-like dyes. Some pharmaceuticals were also made from isatin and its derivatives. Isatin itself is an endogenous MAO inhibitor . Nowadays, isatin derivatives are no longer used in the pharmaceutical industry because of their liver-damaging effects.

Individual evidence

  1. ↑ Entry on ISATIN in the CosIng database of the EU Commission, accessed on June 30, 2020.
  2. ↑ a b entry on Isatin. In: Römpp Online . Georg Thieme Verlag, accessed on June 14, 2014.
  3. ↑ a b c d e Entry on isatin in the GESTIS substance database of the IFA , accessed on December 19, 2019(JavaScript required) .
  4. ↑ T. Sandmeyer: About Isonitrosoacetanilide and their condensation to isatins. In: Helv. Chim. Acta . 2 (1), 1919, pp. 234-242, doi: 10.1002 / hlca . 19190020125 .
  5. ↑ CS Marvel, GS Hiers: Isatin In: Organic Syntheses . 5, 1925, p. 71, doi : 10.15227 / orgsyn.005.0071 ; Coll. Vol. 1, 1941, p. 327 ( PDF ).
  6. ↑ Hans Beyer, Wittko Francke, Wolfgang Walter: Textbook of organic chemistry. 24., revised. Edition. Hirzel, Stuttgart 2004, ISBN 3-7776-1221-9 , pp. 776-777.
  7. ^ Römpp: Basic Lexicon of Chemistry. Georg Thieme Verlag, Stuttgart 1998, ISBN 3-13-115711-9 .