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NCJRS Abstract

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NCJ Number: 220423 Find in a Library
Title: Structure Elucidation of Dyes That Are Formed in the Colorimetric Detection of the Improvised Explosive Urea Nitrate
Journal: Journal of Forensic Sciences  Volume:52  Issue:5  Dated:September 2007  Pages:1107-1110
Author(s): Nitay Lemberger B.Sc.; Joseph Almog Ph.D.
Date Published: September 2007
Page Count: 4
Type: Report (Study/Research)
Format: Article
Language: English
Country: United States of America
Annotation: This paper reports on the preparation and structure determination of the two dyes (red and yellow) formed in a color test for urea nitrate (uronium nitrate), a powerful, improvised explosive popular with terrorists.
Abstract: A sensitive color test for uronium nitrate (UN) was recently developed. It is based on the formation of a red dye in the reaction between p-dimethylaminocinnamaldehyde (p-DMAC) and UN under neutral conditions. A similar reaction with p-dimethylaminobezaldehyde (p-DMAB) produces a yellow dye. This paper describes how sizeable crystals of both dyes were obtained and measured. Crystallographic measurements show that both dyes are mono-ureido nitrate salts, which are protonated on one of the urea nitrogen atoms. In their 1956 article, Cline and Fink, argued for a protonated Schiff based structure for the product of urea and p-DMAB. Their experimental proof of this theory was only partial, based mostly on microanalysis. In a more recent article, Hussain and Shaukat reported a free-base structure for the colored product of urea with p-DMAC. The crystallographic data from the current study confirm the protonated Schiff base structure for both dyes, thus supporting Cline and Fink's assumption. Further, examination of the bond lengths in the two dyes shows that C(2)-C(3) and C(5)-C(6) are the shortest bonds in both aromatic rings, indicating a higher degree of double bond, which shows that the quinoid form prevails in the crystal lattice. 2 tables, 10 figures, and 15 references
Main Term(s): Criminology
Index Term(s): Bomb detection; Explosive detection; Explosives; Explosives tracing; Foreign criminal justice research; Israel; Terrorist weapons
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