57. Acetimidoquinone

Nomenclature

CAS number: 50700-49-7
4-(Acetylimino)-2,5-cyclohexadien-1-one; N-(4-oxo-2,5-cyclohexadien-1-ylidene)acetamide; N-acetyl-p-benzoquinonimine; N-acetylimidoquinone; NAPQI.
C8H7NO2; mol wt 149.15.
C 64.42%, H 4.73%, N 9.39%, O 21.45%.

Description and references

Proposed “ultimate” toxic metabolite of acetaminophen, q.v. Initially prepared by oxidation of acetaminophen with lead tetraacetate and characterized as a Diels-Alder adduct: I. C. Calder et al., J. Med. Chem. 16, 499 (1973) DOI PubMed. Electrochemical generation in buffer: D. J. Miner, P. T. Kissinger, Biochem. Pharmacol. 28, 3285 (1979) DOI PubMed. Synthesis in stable benzene soln and reactivity: I. A. Blair et al., Tetrahedron Lett. 21, 4947 (1980) DOI. Prepn in cryst form, decomposition kinetics, preliminary toxicological studies: D. C. Dahlin, S. D. Nelson, J. Med. Chem. 25, 885 (1982) DOI PubMed. Microsomal reactivity study: G. B. Corcoran, Adv. Exp. Med. Biol. 136B, 1085 (1982) PubMed. Review of acetaminophen-induced hepatotoxicity: J. A. Hinson et al., Life Sci. 29, 107-116 (1981) DOI PubMed.

Chemical structure

Properties

Yellow cubic cryst, mp 74-75°. Sublimes at 45-50° (0.07 mm Hg). uv max (n-hexane): 263, 376 nm (ε 3.3×104, 1.6×102 M1 cm1). LD50 i.p. in male BALB/c mice: 20 mg/kg (Dahlin, Nelson).