Current Organic Chemistry - Volume 11, Issue 3, 2007

Organic and toxic chemicals may cause death, temporary loss of performance or permanent injury in people and animals. If toxic chemicals, their derivatives and synthetic equivalents and toxins that are produced by living organisms are used for military purposes, all of those chemicals can be classified as chemical warfare agents. Since the terrorist attacks of September 11, 2001 and the anthrax incident shortly after in the USA, most people and many governments around the world have shown increasing concern that terrorist organizations may use chemical warfare agents against military as well as civilian targets. Thus, currently, innumerable research papers related to chemical warfare agents have been published in various research fields including Organic Chemistry. The objective of the present issue (Title: “Analytical methods capable of sensing biological and chemical warfare agents and their degradation products based on bio-organic chemistry“) of the Current Organic Chemistry is to review recent research on chemical warfare agents from the viewpoint of Organic Chemistry. This issue contains four review articles written in four different research areas of Organic Chemistry. Zygmunt and his coauthors report the potentialities of solid phase micro-extraction capable of sampling chemical warfare agents in different matrices (e.g., air, water, urine, soil) in the first chapter of this issue. In the second chapter, Giordano and Collins describe a number of analytical methods for sensing biological and chemical warfare agents with a focus on those techniques which depend on synthetic organic chemistry. In the third chapter, Kassa and his coauthors introduce newly developed analogues of commonly used oximes (e.g., pralidoxime, obidoxime, trimedoxime, HI-6) and evaluate their potency to counteract the acute toxicity of nerve agents. Finally, in the fourth chapter, Talmage and his coauthors review decontamination technologies of chemical warfare agents (e.g., HD, VX, GA, GB, GD). Also, they discuss the toxicity of the intermediate and final degradation products with chemical decontamination pathways of each of the chemical warfare agents. I thank all the authors of this issue for their contribution and efforts. It is expected that this issue will be useful to readers working in Organic Chemistry as well as other research fields studying chemical warfare agents.

Solid phase microextraction (SPME) is a very versatile, convenient and simple technique of sample preparation for chromatographic analysis. SPME finds increasingly wide acceptance in the isolation and enrichment of chemical warfare agents (CWAs) and their degradation products in air, water and other liquid samples (e.g. urine), soil, clothing material, etc. for their gas chromatographic (GC) determination. Until now, typical commercially available fibers have mainly been used for the extraction of CWAs in direct immersion and headspace modes, although attempts were made to introduce new fiber coatings, characterized by higher selectivity towards the analytes of interest. The combination of SPME and GC enables reaching low detection limits dependent on the analyte, matrix, detection system, etc.; for example, single ppb for benzilic acid in soil and nerve agents in aqueous samples and 200 ppb for thiodiglycol, a degradation product of sulfur mustard.

Recent events as they relate to the war on terror make it abundantly clear that the rapid detection of chemical warfare nerve agents is essential. While the detection of these agents clearly falls into the purview of the analytical chemist, the importance of the organic chemist in the development of new techniques or approaches remains intact. This review serves to introduce the reader to a number of methods for detecting nerve agents with a focus on those techniques which rely on synthetic chemistry to improve overall performance with respect to selectivity, sensitivity and analysis time.

Highly toxic organophosphorus inhibitors of acetylcholinesterase referred as nerve agents are considered to be among the most dangerous chemical warfare agents. The oximes represent very important part of antidotal medical countermeasures. They are used to reactivate the nerve agent-inhibited acetylcholinesterase. Despite long-term research activities, there is no single, broad-spectrum oxime suitable for the antidotal treatment of poisoning with all organophosphorus agents. Therefore, the development of new structural analogues of currently available oximes should continue to increase the effectiveness of antidotal treatment of poisoning by organophosphorus compounds. The review describes the development of new structural analogues of currently available oximes and the evaluation of their potency to counteract the acute toxicity of some nerve agents (tabun, cyclosarin) in comparison with commonly used oximes (pralidoxime, obidoxime, trimedoxime, HI-6).

The decontamination of chemical warfare agents (CWA) from structures, environmental media, and even personnel has become an area of particular interest in recent years due to increased homeland security concerns. In addition to terrorist attacks, scenarios such as accidental releases of CWA from U.S. stockpile sites or from historic, buried munitions are also subjects for response planning. To facilitate rapid identification of practical and effective decontamination approaches, this paper reviews pathways of CWA degradation by natural means as well as those resulting from deliberately applied solutions and technologies; these pathways and technologies are compared and contrasted. We then review various technologies, both traditional and recent, with some emphasis on decontamination materials used for surfaces that are difficult to clean. Discussion is limited to the major threat CWA, namely sulfur mustard (HD, bis[2-chloroethyl]sulfide), VX (O-ethyl S-[2-diisopropylaminoethyl] methylphosphonothioate), and the Gseries nerve agents. The principal G-agents are GA (tabun, ethyl N,N-dimethylphosphoramidocyanidate), GB (sarin, isopropyl methylphosphonofluoridate), and GD (soman, pinacolyl methylphosphonofluoridate). The chemical decontamination pathways of each agent are outlined, with some discussion of intermediate and final degradation product toxicity. In all cases, and regardless of the CWA degradation pathway chosen for decontamination, it will be necessary to collect and analyze pertinent environmental samples during the treatment phase to confirm attainment of clearance levels.

Many effective strategies have been developed in order to inhibit the hydrodechlorination in the selective hydrogenation of chloronitrobenzenes to chloroanilines which are important intermediates in the chemistry and industry of dyes, herbicides, pesticides and medicines. However, hydrogenolysis of the carbon-halogen bond as a defect of the hydrogenation process could not be avoided completely over the metal catalysts reported previously, especially at complete conversion of the substrates. Recently we overcame this problem by the invention of nanocomposite catalysts composed of noble metal nanoclusters and inorganic semiconductor nanoparticles. Over these nanocomposite catalysts, the hydrodechlorination of ortho-chloroaniline was completely suppressed even at 100% conversion of ortho-chloronitrobenzene. In this review, we deal with the great efforts and remarkable contributions of different authors during the long exploration for the solutions of this hard obstacle. Stress is placed on supported metal catalysts and polymer-protected metal nanoclusters or colloid catalysts.