Article · Wikipedia archive · Last revised Jun 17, 2026

Phthalide

Phthalide is an organic chemical compound with the molecular formula C8H6O2. It is a white solid and the simplest benzo lactone. It is prepared from hydroxymethylbenzoic acid.

Last revised
Jun 17, 2026
Read time
≈ 2 min
Length
399 w
Citations
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Source
Wikipedia ↗
Phthalide
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Phthalide Powder
Names
Preferred IUPAC name
2-Benzofuran-1(3H)-one
Other names
Phthalolactone
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.001.586
UNII
  • InChI=1S/C8H6O2/c9-8-7-4-2-1-3-6(7)5-10-8/h1-4H,5H2
    Key: WNZQDUSMALZDQF-UHFFFAOYSA-N
  • InChI=1/C8H6O2/c9-8-7-4-2-1-3-6(7)5-10-8/h1-4H,5H2
    Key: WNZQDUSMALZDQF-UHFFFAOYAW
  • O=C1OCc2ccccc12
Properties
C8H6O2
Molar mass 134.134 g·mol−1
Melting point 75 to 77 °C (167 to 171 °F; 348 to 350 K)1
Boiling point 290 °C (554 °F; 563 K)2
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Phthalide is an organic chemical compound with the molecular formula C8H6O2. It is a white solid and the simplest benzo lactone. It is prepared from hydroxymethylbenzoic acid.3

Phthalides

The phthalide core is found in a variety of more complex chemical compounds including dyes (such as phenolphthalein), fungicides (such as tetrachlorophthalide, often referred to simply as "phthalide"), and natural oils (such as butylphthalide).

Examples

5-bromophthalide [64169-34-2] is used in the synthesis of Roxadustat and Citalopram.

3-(4'-chlorophenyl)phthalide is a chemical that serves function in the synthesis of Setazindol4 & Chlortalidone.5

Synthesis

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Phthalide synthesis:6

Uses

Phthalide has known uses in the synthesis of hydralazine,57 & pipethiadene.89

Phthalide is used in the synthesis of dibenzosuberone.

References

References

  1. Kumar, R. Arun; Maheswari, C. Uma; Ghantasala, Satheesh; Jyothi, C.; Reddy, K. Rajender (2011). "Synthesis of 3H-Quinazolin-4-ones and 4H-3,1-Benzoxazin-4-ones via Benzylic Oxidation and Oxidative Dehydrogenation using Potassium Iodide-tert-Butyl Hydroperoxide". Advanced Synthesis & Catalysis. 353 (2+3): 401–410. doi:10.1002/adsc.201000580.
  2. Kus, Nermin Simsek (2008). "Some oxidation reactions with molecular oxygen in subcritical water". Asian Journal of Chemistry. 20 (2): 1226–1230.
  3. J. H. Gardner; C. A. Naylor, Jr (1936). "Phthalide". Organic Syntheses. 16: 71. doi:10.15227/orgsyn.016.0071.
  4. Elks, J., Ganellin, C. R., eds. (1990). Dictionary of drugs: chemical data, structures, and bibliographies (1st ed.). Chapman and Hall. ISBN 9780412273001.
  5. Vardanyan, R. S., Hruby, V. J. (2006). Synthesis of essential drugs (1st ed.). Elsevier. ISBN 9780444521668.
  6. "PHTHALIDE". Organic Syntheses. 16: 71. 1936. doi:10.15227/orgsyn.016.0071.
  7. Druey, J., Ringier, B. H. (January 1951). "Hydrazinderivate der Phtalazin‐ und Pyridazinreihe". Helvetica Chimica Acta. 34 (1): 195–210. doi:10.1002/hlca.19510340122.
  8. Protiva, M. (1983). "Pipethiadene Tartrate". Drugs of the Future. 8 (4): 334. doi:10.1358/dof.1983.008.04.65210. ISSN 0377-8282.
  9. Polívka, Z., Rajšner, M., Metyš, J., Holubek, J., Svátek, E., Ryska, M., Protiva, M. (1983). "Antiaminic agents derived from thieno[2,3-c]-2-benzothiepin: 4-(1-Methyl-4-piperidylidene)-4,9-dihydrothieno[2,3-c]-2-benzothiepin and some related compounds". Collection of Czechoslovak Chemical Communications. 48 (2): 623–641. doi:10.1135/cccc19830623.