Zimmermann reaction

What is Zimmermann reaction?

The Janovsky and Erb reaction between an enolate carbanion and m-dinitrobenzene (m-DNB) was first reported in 1886. The specific reaction between m-dinitrobenzene and 17-oxo-steroids (or 17-keto-steroids) in the presence of an alkali was applied to the field of ketosteroid analysis by Zimmermann.

This reaction is commonly known as the Zimmermann reaction, or occasionally referred to as the Zimmermann color reaction or Callow-Zimmermann reaction. It is important to note that the reaction is commonly misspelled as the Zimmerman reaction.

Zimmermann reaction - general reaction scheme - Zimmermann color reaction - Callow-Zimmermann reaction -  misspelled Zimmerman reaction
Zimmermann reaction

Although other ketones and aldehydes with α-methylene groups also react with m-dinitrobenzene, the molecules bearing the cyclopentanone moiety will afford a characteristic magenta color, with a maximal absorbance between 510 and 530 nm. The Zimmermann reaction chromogen is the magenta color that develops from 17-oxo-steroids with a methylene group at position 16. The Zimmermann reaction is routinely used for the androgenic assay, urine test, and peripheral human plasma analysis. It is also adaptable for the assay of prostaglandin synthetase, which converts arachidonic acid into Prostaglandin E2 PGE2 only in the presence of glutation GSH.

It is important to note that the Zimmermann reaction is affected by interference from carbonyl compounds, which are not related to 17-oxo-steroids, such as 3-, 6-, and 20-oxo-steroids. Urine extracts also give brown chromogens in this reaction. The absorbance for a mixture of steroids, strong base, and m-dinitrobenzene continually increases at room temperature, even if the solution is diluted with absolute or aqueous alcohol, whereas such absorbance enhancement is only slightly noticeable when the solution is stored at 0 ºC. Furthermore, even the blank absorbance arising from dinitrobenzene and KOH increases phenomenally upon long incubation, probably due to the formation of 2,5-dinitrophenoxide from the nucleophilic substitution by hydroxide followed by deprotonation. It is interesting to note that cats are unlikely to excrete 17-oxo-steroids in the urine.

References

  • Janovsky, J. V. and Erb, L., Ber., 1886, 19, 2155
  • Zimmermann, W., Z. Physiol. Chem., 1935, 233, 257
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