Bank Security Dye Packs: Synthesis, Isolation, and Characterization of Chlorinated Products of Bleached 1-(methylamino)anthraquinone
Banknote evidence is often submitted after a suspect has attempted to disguise or remove red dye stain that has been released because of an anti-theft device that activates after banknotes have been unlawfully removed from bank premises. Three chlorinated compounds have been synthesized as forensic chemical standards to indicate bank security dye bleaching as a suspect's intentional method for masking a robbery involving dye pack release on banknotes. A novel, facile synthetic method to provide three chlorinated derivatives of 1-(methylamino)anthraquinone (MAAQ) is presented. The synthetic route involved Ultra Clorox™ bleach as the chlorine source, iron chloride as the catalyst, and MAAQ as the starting material and resulted in a three-component product mixture. Two mono-chlorinated isomers (2-chloro-1-(methylamino)anthraquinone and 4-chloro-1-(methylamino)anthraquinone) and one di-chlorinated compound (2,4-dichloro-1-(methylamino)anthraquinone) of the MAAQ parent molecule were detected by gas chromatography mass spectrometry (GC-MS), and subsequently isolated by liquid chromatography (LC) with postcolumn fraction collection. Although GC-MS is sensitive enough to detect all of the chlorinated products, it is not definitive enough to identify the structural isomers. Liquid-state nuclear magnetic resonance (NMR) spectroscopy was utilized to elucidate structurally the ortho- and para-mono-chlorinated isomers once enough material was properly isolated. A reaction mechanism involving iron is proposed to explain the presence of chlorinated MAAQ species on stolen banknotes after attempted bleaching.
Document Type: Research Article
Affiliations: 1: Federal Bureau of Investigation, Laboratory Division, Counterterrorism and Forensic Science Research Unit, FBI Academy, Building 12, Quantico, VA 22135. 2: Federal Bureau of Investigation, Laboratory Division, Chemistry and Biological Sciences Unit, FBI Laboratory, 2501 Investigation Parkway, Quantico, VA 22135. 3: CFSRU-ORISE, Federal Bureau of Investigation, Laboratory Division, Counterterrorism and Forensic Science Research Unit, FBI Academy, Building 12, Quantico, VA 22135. 4: Department of Chemistry, Pennsylvania State University, University Park, PA 16802.
Publication date: November 1, 2006