Pharmaceutisch weekblad

, Volume 3, Issue 1, pp 800–809 | Cite as

Photochemical activity of 7-nitro-1,4-benzodiazepines

Formation of singlet molecular oxygen, isolation and identification of decomposition products
  • P. J. G. Cornelissen
  • G. M. J. Beijersbergen Van Henegouwen
Original Articles


The photochemical activity of nitrazepam, clonazepam and flunitrazepam has been investigated. These closely structurally related compounds decompose photochemically in an oxygen-poor medium, resulting in photoreductive dimerisation and photoreduction of the nitro-group to successively the nitroso, the hydroxylamino and finally the amino analogue of the nitro-compound. The photoreductive dimerisation compound is a result of a coupling reaction between the respective nitroso and hydroxylamino derivatives.

In an oxygen-rich medium, however, the 7-nitro-1,4-benzodiazepines are relatively photostable. It appears that the quenching of excited clonazepam and nitrazepam leads exclusively to the formation of singlet molecular oxygen, while in the case of flunitrazepam, beside singlet molecular oxygen, also another reactive oxygen-dependent species is formed.

In addition the photochemical activity of methylnitrazepam, methylclonazepam and desmethylflunitrazepam has been investigated. It appears that a relationship exists between the 7-nitro group in the 1,4-benzodiazepine nucleus and the photochemical behaviour.


Methylene Blue Clonazepam Nitroso Flunitrazepam Nitrazepam 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Bohn, Scheltema & Holkema 1981

Authors and Affiliations

  • P. J. G. Cornelissen
    • 1
  • G. M. J. Beijersbergen Van Henegouwen
    • 1
  1. 1.Department of Pharmacochemistry, Subfaculty of PharmacyState University of Leiden, Gorlaeus LaboratoriaRA LeidenThe Netherlands

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