Properties sulfur mustard

Properties. The physical properties of the mustards are summarized in Table 1. The sulfur mustards are only slightly soluble in water, whereas the nitrogen mustards are slightly soluble at neutral pH, but form water-soluble salts under acid conditions. Both sulfur and nitrogen mustards are extremely soluble in most organic solvents. 

The interplay between the chemical and biological properties of the threat agent, on the one hand, and the specific attack scenario, on the other, can influence the lethality of the attack. Table 2-2 shows the relative respiratory toxicities (expressed as the lethal concentration of toxin at which 50 percent of test animals are killed, or LCT50, in milligrams per minute per cubic meter) of a variety of toxic gases compared with chlorine gas, which was used as a chemical weapon in World War I. According to Table 2-2, the nerve agent sarin (GB) has a respiratory toxicity approximately 100 times that of chlorine, while sulfur mustard (HD) is about 7 times more toxic. However, the lethality of an attack... 

Sulfur mustard (mustard gas) remains one of the CW agents of greatest concern because of its ease of production, favorable physicochemical properties, and potent vesicant action. It is a bifunctional alkylating agent, which reacts rapidly under physiological conditions with nucleophilic sites in proteins and DNA to form covalent adducts, via an intermediate episulfonium ion (see Figure 1). In the sections below, the various adducts (as unambiguously elucidated in recent years by mass spectrometry) are addressed, and methods for their analysis are discussed. 

The data base for sulfur mustard contains two developmental toxicity studies in different species, a reproductive bioassay and a standard subchronic toxicity study in one species. In addition, chronic inhalation studies have been conducted on sulfur mustard using rats, mice, guinea pigs and dogs. The principal study identifies a toxic effect that is consistent with the vesicant properties of sulfur mustard. There is no evidence that any other experimental species would be more sensitive to ingested sulfur mustard therefore, additional oral toxicity studies in other species are not considered critical. 

Watson and Griffin (1992) have summarized information on the distribution of unitary chemical weapon stockpiles in the USA. The chemical and physical properties of sulfur mustard (agent HD) are shown in Table 8.2. 

TABLE 8.2. Selected physical and chemical properties of sulfur mustard... 

Obviously, these findings confirm the theoretical assumption that the lipophilic properties of sulfur mustard result in a distribution, primarily in lipophilic tissues. High concentrations found in the brain may also explain why the central nervous system is one of the organs exhibiting systemic effects of sulfur mustard poisoning, even though it is not a site of rapidly proliferating cells. 

Similar to bleach s oxidative iodine properties, topical povidone-iodine at 15 and 30 min post-exposure to sulfur mustard exhibited protective effects. Severity of the dermal parameters, acute inflammation and dermal necrosis was significantly reduced, and reduced skin damage was observed in areas adjacent to treated sites (Brodsky and Wormser, 2007). 

Sulfur mustard is the distilled or purified form of mustard gas. Its properties and toxicities are similar to those of mustard gas. If spilled, sulfur mustard evaporates into air where it decomposes. It can persist within soil with its blister-forming activity intact for many years, particularly in colder climates. Because of its relative insolubility, it generally does not contaminate groundwater. 

The toxicities and properties of HT are similar to those of mustard gas or sulfur mustard. 

Phenyldichlorarsine, ethyldichloroarsine, and methyl-dichloroarsine have similar properties and toxicities as lewisite. They may be mixed with sulfur mustard similarly as can be done with lewisite and mustard mixtures, and this can confuse the diagnosis between either an arsenical or a mustard injury. 

In the case of sulfur-mustard, the situation is somewhat more complex. It is marginally soluble in water tending to form droplets, and hydrolysis occurs at the droplet surface. This property has made measuring the hydrolysis rate constant difficult, and half-lives anywhere from 2 to 30 hours are reported. Chemically, the hydrolysis of HD involves the sequential replacement of the chlorine atoms by hydroxyl groups through cyclic sulfonium ion intermediates to form thiodiglycol (TDG), Reaction (2). If a median... 

Physical Properties Sulfur mustard (mustard gas) is a colorless oil with bp of 227°C, mp of 14°C, molecular dipole moment 1.78 D (hexane), and molecular mass of 159. It normally is encountered as an impure, pale yellow-brown, odoriferous liquid. The color generally deepens with increasing amounts of impurity. HD has a vapor density of 5.4 relative to air and a vapor pressure of 0.072 mm Hg at 20°C. As a liquid, it is slightly denser than water (1.27 g/mL at 20°C). It is miscible in typical organic solvents (e.g., carbon tetrachloride, acetone or chloroform) but has a lower solubility in water (0.092 g/100 g at 22°C) (Sidell et al., 1998 Somani, 1992). 

Nitrogen mustards have not been stockpiled in most countries and are not further discussed here other than to say that their chemical properties resemble those of sulfur mustard (IOM, 1993). The toxicity and environmental fate of the nitrogen mustard agents have been reviewed previously (Marrs et al., 1996 Munro et al., 1999). Based on chemical properties, the persistence of nitrogen mustards range from environmentally persistent (tris[2-chloroethyl] amine... 

The fate of HD in the environment is determined by its chemical and physical properties. Observations of persistence and degradation products from both field and laboratory studies support the characterization of HD as a persistent agent. As noted, sulfur mustard is a liquid at ambient temperatures the vapor pressure is low (0.11 mmHg at 25°C), but sufficient for mustard to be in the air immediately surrounding droplets of the liquid. The primary dissipation mechanism for HD from soil is evaporation. Sulfur mustard vapor is 5.5 times heavier than air, and evaporation or volatilization from surfaces or soils is projected to require days at temperatures above its freezing point (Puzderliski, 1980). Below its... 

Table 2. Physical properties of sulfur mustard degradation products0 6 ...

The physical, chemical and hazardous properties of a number of highly toxic or flammable substances that were in the past or being currently used in the warfare have been discussed in detail in several chapters in this book. Some of these compounds are further discussed under specific chapters, such as. Sulfur Mustards, Nerve Gases, Dioxin and Related Compounds and Napalm. These and many other compounds are in most cases grouped together in this book based on their chemical structures along with their toxic or flammable properties. Presented below is a brief discussion on various types of chemicals weapons developed for military applications. Explosive substances have been omitted from this section. They are discussed separately in this book under topics such as Explosive Characteristics of Chemical Substances, Nitro Explosives, Oxidizers and Organic Peroxides and also under specific title compounds in various chapters. 

The term blister agents includes a wide range of compounds with diverse physical and chemical properties and chemical structures. They may be broadly grouped under a few general types, namely, the sulfur mustards, nitrogen mustards and organochloro-arsines. There are also some substances that do not fall nnder the above categories. 

The oxidation products of Sulfur mustards, sulfones are also vesicants but their blistering actions on skin are much less. They have not been used in the warfare. Dimethyl snlfate, (CH3)2S04 is another highly toxic organosnlfnr compound causing severe blisters from skin contact. This compound was nsed in the past as a military poison. Its physical, chemical and toxic properties are presented nnder Sulfate Esters in Chapter 55. 

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