Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

The equilibrium between the iso and the normal forms of 9-nitrofluorene


  1. 1.

    A series of bromometric titrations of solution of iso-9-nitrofluorene in ethanol, dioxane and benzene was run.

  2. 2.

    The iso-form is thermodynamically more stable in the crystalline form than is the normal form; equilibria are established in solution in which the content of the normal form is greater with lower polarity of the solvent. The normal form of 9-nitrofluorene cannot be isolated since it disproportionates forming 1,2-dinitro1,2-dibiphenylene-ethane and fluorenone oxime. This reaction occurs at a lower rate than the reaction of formation of the normal form from the iso-form. Consequently, temporarily large concentrations of the normal form exist in solution and these were established by a chemical route.

  3. 3.

    The greater stability of the iso-form of 9-nitrofluorene is determined by the tendency of the cyclopentadiene ring to form an aromatic sextet by attracting electron pairs from the nitro group.

This is a preview of subscription content, log in to check access.

Literature cited

  1. [1]

    F. R. Gross and C. K. Ingold, J. Chem. Soc. 1928, 1268.

  2. [2]

    G. W. Wheland and D. E. Mann, J. Chem. Phys. 17, 264 (1949); E. D. Bergmann and E. Fischer, Bull. Soc. chim. France, 1684 (1950).

  3. [3]

    D. Lloyd and J. S. Snezum, Chemistry and Industry, 1221 (1955).

  4. [4]

    F. Ramirez and S. Levy, J. Organ. Chem. 21, 488 (1956).

  5. [5]

    W. v. E. Doering and C. H. DePuy, J. Amer. Chem. Soc. 75, 5955 (1953).

  6. [6]

    C. F. H. Allen and J. A. Van Allan, J. Amer. Chem. Soc. 72, 5165 (1950).

  7. [7]

    C. K. Ingold and J. A. Jessop, J. Chem. Soc. 1930, 713.

  8. [8]

    L. Horner and E. Lingnau, Liebigs Ann. Chem. 591, 23 (1955).

  9. [9]

    C. D. Nenitzescu and D. A. Isacescu, Ber. Dtsch. Chem. Ges. 63, 2484 (1930).

  10. [10]

    W. Wislicenus and M. Waldmüller, Ber. Dtsch. Chem. Ges. 41, 3334 (1908).

  11. [11]

    C. K. Ingold, Structure and Mechanism in Organic Chemistry, Cornell University Press, N. Y. 1953, p. 535.

  12. [12]

    D. Turnbull and S. H. Maron, J. Amer. Chem. Soc. 65, 212 (1943).

  13. [13]

    J. Thiele, Ber. Dtsch. Chem. Ges. 33, 670 (1900).

  14. [14]

    W. Wislicenus and K. Pfeilsticker, Liebigs Ann. Chem. 436, 36 (1924).

  15. [15]

    K. H. Meyer and P. Kappelmeyer, Der. Dtsch. Chem. Ges. 44, 278 (1911); K. H. Meyer, ibid, 45, 2843 (1912).

  16. [16]

    K. H. Meyer and P. Wertheimer, Ber. Dtsch. Chem. Soc. 47, 2374 (1914).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Nenitzescu, K.D., Dinulescu, I.G. The equilibrium between the iso and the normal forms of 9-nitrofluorene. Russ Chem Bull 7, 1185–1189 (1958).

Download citation


  • Benzene
  • Titration
  • Normal Form
  • Dioxane
  • Oxime