We have synthesized a homologous series of soluble, linearly conjugated oligomers and related polymers using molybdenum alkylidene catalysts. We have developed HPLC procedures to isolate the oligomers according to their chain lengths and have obtained the absorption spectra of the purified oligomers in room temperature solutions and in 77 K glasses. The oligomer absorption spectra are structured and remarkably similar to those of simple polyenes with comparable numbers of conjugated double bonds (N). Furthermore, the electronic origins of the low-energy, strongly allowed 1 1 A g -f 1 1 B u + transitions follow the E(0-0) ) A + B/N behavior previously noted in simple polyenes and carotenoids. Extrapolation of data for oligomers with N ) 3-15 suggests E(0-0) ≈ 14 000 cm -1 (λ ≈ 700 nm) in the long polyene limit. The oligomer spectra exhibit modest red shifts on cooling, suggesting minimal conformational disorder in the room temperature samples. In contrast, the absorption spectrum of the longest soluble polymer (N > 100) in this series undergoes a significant red shift and sharpening upon cooling from 300 to 77 K. This indicates that the room temperature polymer is disordered due to relatively low thermal barriers for torsional motion about carbon-carbon single bonds. Unlike the longer oligomers, the low-temperature absorption of the polymer shows well-defined vibronic structure. The polymerization reactions lead to a distribution of conjugation lengths in the unpurified polymer sample. However, the vibronically resolved, red-shifted absorption at low temperature (λ(0-0) ) 630 nm) indicates that this distribution is dominated by species with very long conjugation lengths. The resolution of the low-temperature spectrum argues that the absorption is due to the superposition of almost identical 1 1 A g -f 1 1 B u + spectra and that all conjugated segments in this sample absorb near the asymptotic limit (1/N ≈ 0).
Gamma-hydroxybutyrate (NaGHB) is a central nervous system depressant originally used as an anesthetic adjunct in Europe more than 30 years ago (1) (Fig. 1). It is known to promote the release of growth hormones and was used both for muscle growth and as a sleep aid among bodybuilders during the 1980s (2,3). In 1989, NaGHB abuse began to increase due to its marketing as the replacement for L-tryptophan (4). In early 1990, hospital emergency rooms across the United States reported numerous cases of NaGHB overdose and related poisoning episodes (5), prompting several states to ban over-the-counter sales of NaGHB and NaGHBcontaining "supplements" in 1990. Following the ban, NaGHB was manufactured clandestinely from gamma-butyrolactone (GBL) (Fig. 2). NaGHB is currently abused for its hypnotic and euphoric effects and is commonly encountered at "rave parties" and in drug-aided sexual assault cases. There has been a widespread increase of NaGHB-related emergency room visits with 56 recorded visits in 1994 to 4969 visits in 2000 (6). On February 18, 2000, the Hillory J. Farias and Samantha Reid Date-Rape Drug Prohibition Act of 1999 (Public Law 106-172) was signed and became Federal law. This law directed DEA to place GHB into Schedule I of the Controlled Substances Act (CSA). The final rule issued by DEA became effective on March 13, 2000 (the same day it was published in the Federal Register). It also placed GBL as a List I chemical. If, however, GBL is intended for human consumption and meets the definition of a Controlled Substance Analog in the CSA (21 USC 802(32), it could be treated as a Schedule I Controlled Substance. GHB-containing products manufactured, distributed or possessed in accordance with FDA authorized Investigational New Drug exemptions under the Federal Food, Drug and Cosmetic Act are placed into Schedule III, if or when they are approved. The common means of identification of NaGHB involves using FTIR or derivatization followed by GC-MS. However, samples containing mixtures of NaGHB, GBL and/or other impurities require cleanup procedures such as acid/base extraction followed by evaporation of excess water prior to FTIR determination (7,8). Because NaGHB converts to GBL in heated injection ports, the identification of the original material by GC or GC-MS cannot be attempted without preliminary derivatization (9,10). In addition, sample preparation can affect the outcome of the analysis. The interconversion between NaGHB and GBL (Fig. 3) is very pH dependent, and any equilibrium shift during cleanup and derivatization can pose problems in the analysis (11). Although the lactone cannot be directly derivatized, in some cases, low levels of lactone may convert into GHB and then be derivatized. This has been detected in some derivatization experiments in the DEA Western laboratory using trimethylsilylating agents. High Pressure Liquid Chromatography/Ultraviolet-Visible Spectrophotometry (HPLC/ UV-VIS), and HPLC/thermospray mass spectrometry have been used for separation and quantitation of GHB, and the ...
Abuse of the hypnotic quinazolinone is well recognized and increasing. Clandestine laboratories producing methaqualone (2-methyl-3-othro-tolyl-4(3H) quinazolinone) and mecloqualone (2-methyl-3-othro-chlorophenyl-4(3H) quinazolinone) have been discovered throughout the United States. These laboratories utilize one of many synthesis routes to produce the illicit quinazolinone. Frequently, the clandestine chemist has little, if any, formal education in chemistry; does not keep notes; and does not label flasks and beakers containing solutions. The forensic chemist may be asked to analyze unmarked reaction mixtures that were seized in a clandestine laboratory raid. As a result, a rapid method of isolation and identification of the precursors and products of such a mixture is presented.
A submission to the Drug Enforcement Administration North Central Laboratory of a substance believed to be a structural analog of methaqualone hydrochloride precipitated an interest in being able to obtain a rapid and positive identification of such compounds. Both mass spectrometry and proton NMR spectroscopy (1-dimensional) provided evidence to suggest that the structural analog possessed a second methyl group in the molecule, relative to methaqualone, and that the methyl group was attached to the existing methylsubstituted phenyl ring. By application of proton 2-dimensional (2-D) NMR techniques, specifically the homonuclear shift correlation spectroscopy (COSY) and 2-D NOE (NOESY), the precise location of the methyl group in this unknown methaqualone analog was established and shown to have the structure 2.
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