Structure elucidation of dyes that are formed in the colorimetric detection of the improvised explosive urea nitrate

Nitay Lemberger, Joseph Almog*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Urea nitrate (uronium nitrate, UN) is a powerful, improvised explosive that can be easily made from urea and nitric acid. It is considered the most frequently used, illegal explosive in the Israeli arena, which is responsible for the loss of more than a hundred lives in terrorist incidents. Urea nitrate is a colorless, crystalline substance that looks very much like sugar. A sensitive color test for UN was developed recently. It is based on the formation of a red dye in the reaction between p-dimethylaminocinnamaldehyde and UN under neutral conditions. A similar reaction with p-dimethylaminobezaldehyde produces a yellow dye. The two dyes have been synthesized, and their structures determined by X-ray crystallography. Both dyes are protonated Schiff bases, prevailing in the crystal in a quinoid form. They are identical to the compounds, which are obtained in the colorimetric detection of urea with the same reagents, under strong acidic conditions, whose structures have been postulated in the literature, but never fully proved experimentally.

Original languageEnglish
Pages (from-to)1107-1110
Number of pages4
JournalJournal of Forensic Sciences
Volume52
Issue number5
DOIs
StatePublished - Sep 2007

Keywords

  • Colorimetric detection
  • Crystallography
  • Forensic science
  • Nonlinear optics
  • p- dimethylaminobenzaldehyde
  • p-dimethylaminocinnamaldehyde
  • Schiff base
  • Urea
  • Urea nitrate
  • Uronium nitrate

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