Isatoic anhydride

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Isatoic anhydride
Isatoic anhydride.PNG
Preferred IUPAC name
ECHA InfoCard 100.003.869 Edit this at Wikidata
Molar mass 163.132 g·mol−1
Appearance white solid
Melting point 243 °C (469 °F; 516 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Isatoic anhydride is an organic compound derived from anthranilic acid. A white solid, it is prepared by reaction of anthranilic acid with phosgene.[1]


Hydrolysis gives carbon dioxide and anthranilic acid. Alcoholysis proceeds similarly, affording the ester:

C6H4C2O3NH + ROH → C6H4(CO2R)(NH2) + CO2

Amines also effect ring-opening. Active methylene compounds and carbanions replace oxygen giving hydroxyquinolinone derivatives. Deprotonation followed by alkylation gives the N-substituted derivatives. Sodium azide gives the benzimidazolone via the isocyanate.[2] Isatoic anhydride is used as a blowing agent in the polymer industry, an application that exploits its tendency to release CO2.

Isatoic anhydride has also been reported to be used as a precursor for the synthesis of methaqualone and related 4-quinazolinone based pharmaceutical drugs.[3]


  1. ^ E. C. Wagner, Marion F. Fegley. (1947). "Isatoic anhydride". Org. Synth. 27: 45. doi:10.15227/orgsyn.027.0045.{{cite journal}}: CS1 maint: uses authors parameter (link)
  2. ^ Coppola, Gary M. (1980). "The Chemistry of Isatoic Anhydride". Synthesis. 7 (7): 505–36. doi:10.1055/s-1980-29110.
  3. ^ A survey of reported syntheses of methaqualone and some positional and structural isomers Etienne F. van Zyl Forens. Sci. Int. 122, 142-149 (2001)