Fourier Transform Infrared/Raman Differentiation and Characterization of Cis- and Trans-2, 5-Dimethoxy-4, B-Dimethyl-B-Nitrostyrenes: Precursors to the Street Drug STP

• NCJ Number: 136020
• Journal: Journal of Forensic Sciences Volume: 37 Issue: 2 Dated: (March 1992) Pages: 503-512
• Author(s): A By; G A Neville; H F Shurvell
• Date Published: 1992
• Length: 10 pages
• Sponsoring Agency: Health and Welfare Canada
• Publication Format: Article
• Publication Type: Test/Measurement
• Language: English
• Country: United States of America

Annotation

This article reports the first successful preparation and separation of (z)-2, 5 dimethoxy-4, B-dimethyl-B-nitrostyrene from its E isomer, together with complete vibrational differentiation and characterization of these two important (E,Z)-B-methyl-B-nitrostyrenes by Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectroscopy.

Abstract

Trans(E)-2, 5-dimethoxy-4, B-dimethyl-B-nitrostyrene, a readily prepared and abundant geometrical isomer, is the essential precursor of the street drug (2.5-dimethoxy-4-methylphenyl) isopropylamine (STP or DOM). FT-Raman and infrared spectra of pure cis(Z)- and trans (E)-2, 5-dimethoxy-4, B-dimethyl-B-nitrostyrene were recorded in the solid state. The spectra show characteristic features of the ethylene moiety and of the aryl and nitro substituents that permit ready differentiation and identification of these isomers. A very strong Raman line at 1670 cm-1 from the cis isomer for the C=C stretching mode, in comparison with a strong Raman line at 1641 cm-1 for the trans isomer, affords primary differentiation of these substances. A second characteristic of both the Raman and infrared spectra is that the frequency of the strong symmetric nitro (N02) stretching band is about 40 cm-1 higher in the cis (1346 cm-1) than the trans isomer (1301 cm-1). All major IR and Raman bands are reported and given vibrational assignments. 5 figures, 1 table, and 12 references (Author abstract modified)