Lewisite solubility

Rapid for vapor and dissolved Lewisite-1. Low solubility in water limits the hydrolysis. 

Lewisite [dichloro(2-chlorovinyl)arsine] is an organic arsenical known for its vesicant properties (Rosenblatt et al., 1975). It has a molecular weight of 207.32, vapor pressure of 0.58 mm HG at 25°C, a liquid density of 1,89 g/cm at 25°C, freezing point of -18°C, boiling point of 190°C, and is negligibly soluble in water (DA, 1974). The chemical structure of lewisite is shown below. Lewisite may occur as a trans-isomer and as a cis-isomer. In aqueous solutions, the cis-isomer undergoes photoconversion to the trans-isomer (Clark, 1989). hi the presence of moisture, lewisite is rapidly converted to the more stable but highly toxic lewisite oxide (2-chlorovinylarsenous acid) (Cameron et al., 1946). 

Althongh lewisite is only slightly soluble in water, 0.5 g/L (Rosenblatt et al., 1975), hydrolysis, resulting in the formation of lewisite oxide and HCl is rapid. Qi-Lewisite mnst be heated to over 40°C to react with NaOH to yield vinyl chloride, sodium arsenite, and acetylene (Rosenblatt et al., 1975). In aqneons solution, the cis isomer nndergoes a photoconversion to the trans isomer (Rosenblatt et al., 1975). Upon standing in water, the toxic trivalent arsenic of lewisite oxide is converted to the less toxic pentavalent arsenic (Epstein, 1956). 

Lewisite in soil may rapidly volatilize or may be converted to lewisite oxide due to moisture in the soil (Rosenblatt et al, 1975). The low water solubility suggests intermediate persistence in moist soil (Watson and Griffin, 1992). Both lewisite and lewisite oxide may be slowly oxidized to 2-chlorovinylarsonic acid (Rosenblatt et al, 1975). Possible pathways of microbial degradation in soil include epoxidation of the C=C bond and reductive deha-logenation and dehydrohalogenation (Morrill et al, 1985). Due to the epoxy bond and arsine group, toxic metabolites may result. Additionally, residual hydrolysis may result in arsenic compounds. Lewisite is not likely to bioaccumulate. However, the arsenic degradation products may bioaccumulate (Rosenblatt et al, 1975). 

Two water-soluble analogs of dimereaprol have also been been studied as lewisite antidotes. They are meso 2,... 

The oil-soluble BAL (British anti-Lewisite 2,3-dimer-captopropanol) administered intramuscularly appears to be the antidote of choice for antimony poisoning. The antidotal action of BAL depends on its ability to prevent or break the union between antimony and vital enzymes. 

The Germans developed several arsenical-based warfare chemical agents circa 1917 (Goldman and Dacre, 1989). The allies, on the other hand, developed Lewisite (2-chlorovinydichloroarsine), adamsite (diphenylaminechloroarsine), methyldichloroarsine, and arsine. Lewisite is soluble in organic solvents it is readily absorbed by rubber, paint, varnish, and porous materials. There are labile chlorine atoms, bivalent arsenic, carbons, and multiple bonds that make it quite reactive. Some of its reactions are due to nucleophilic substitution by water, hydrogen sulfide, thiols, and acid salts. 

Lewisite is the only vesicant with a proven antidote—British anti-lewisite (2,3-dimercaptopropa-nol). Increasing antioxidant levels have been found to be protective against the mustards analog, NAC. NAC, which we have used in our studies with CEES, is immediately clinically available. It is most commonly used for acetaminophen overdose. NAC has a long history of several gram quantities administered in several doses and has minimal adverse reactions. In the case of acetaminophen overdose, it is administered via the oral-gastric route, which increases hepatic GSH levels, and in turn, suppresses inflammatory cytokines (Dambach et al., 2006). Liposome encapsulation of both water- and fat-soluble antioxidants was proven to be more effective in the suppression of OS than the free molecule of NAC. 

Lewisite is practically insoluble in water, but the small amount that dissolves is rapidly hydrolyzed (Rosenblatt et al., 1975), resulting in the formation of the water-soluble dihydroxy arsine or 2-chlorovinyl arsonous acid. Lewisite in solution becomes essentially 100% 2-chlorovinyl arsonous acid (Major, 1998) ... 

Lewisite is an odorless, colourless oily liquid of structural formula ClCH-CHAsC12 (Table 2). Lewisite is said to darken on standing and the technical material is often blue-black to black in colour and is said to smell of geraniums. Lewisite, which is not soluble in water to... 

Two water-soluble analogs of dimercaprol have been studied as lewisite antidotes, namely meio-2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercapto- 1-propane sulfonic acid (DMPS) (see review by Aposhian, 1993). Their structures are as follows ... 

DMPS and DMSA applied to the skin would probably be of value in lewisite-induced vesication. However, the disadvantages of dimercaprol largely relate to systemic treatment and the water-soluble analogues are unlikely to be better than dimercaprol ointment. 

L In a pure form Lewisite is a colorless and odorless liquid, but usually contains small amounts of impurities that give it a brownish color and an odor resembling geranium oil. It is heavier than mustard, poorly soluble in water but soluble in organic solvents. 

British Anti-Lewisite (BAL) is a dithiol used as an antidote in mercury poisoning. It was originally developed as an antidote to a mustard-gas-hke chemical warfare agent called Lewisite. Lewisite was developed near the end of World War I and never used. By the onset of World War II, Lewisite was considered to be obsolete because of the discovery of BAL, an effective, inexpensive antidote. The two thiol groups of BAL form a water-soluble complex with mercury (or with the arsenic in Lewisite) that is excreted from the body in the urine. 

Besides stopping the exposure to mercury and medically treating the symptoms, as in cases of acute or chronic mercury intoxication, the renal and fecal excretion of mercury may be increased by the application of a chelating agent. BAL (British Anti-Lewisite, Dimercaprol) is still used for this purpose in some countries, but has several disadvantages compared with more effective, water-soluble derivatives such as 2,3-dimer-... 

Fig. 4-2. Agent vaporization increases in proportion to energy sources such as heat from explosive charges or from ambient heat (as measured by air or surface temperatures). Vapor persistence is then determined by weather factors such as wind and humidity. Hydrolysis rates are affected by factors such as temperature and solubility. Agents show characteristic hydrolysis rates in water, and water vapor, as described by humidity, may cause significant hydrolysis of vaporized agent. The vesicant Lewisite, for example, shows relatively rapid hydrolysis in water vapor, while the nerve agent VX is more resistant to hydrolysis.

Water. Although lewisite is only slightly soluble in water, 0.5 g/L (Rosenblatt et al. 1975), hydrolysis resulting in the formation of lewisite oxide and HCl is rapid. The hydrolysis is complex, with a number of reversible reactions (Clark... 

Lewisite (a-lewisite or 2-chlorovinyl dichloroarsine) is only slightly soluble in water but when dissolved it hydrolyses rapidly into 2-chlorovinylarsine oxide. The oxide is fairly soluble in sea water. In an alkali solution a further reaction into acetylene and arsenic acid might be possible. With high turbulence, lewisite can dissolve more rapidly in large volumes of water. Because lewisite is 36 per cent arsenic by weight, even if broken down, a toxic element would always remain. 

It turned out that lewisite reacts with water immediately (in fractions of a second) and forms a slightly soluble compound P-chlorovinylarsineoxide. In the case of large amounts of lewisite being ingressed in water, it will deposit on the bottom being immediately covered by a layer of p-chlorovinylarsineoxide, which prevents lewisite s dissolution and hydrolysis. 

The situation for contaminants, containing arsenic (lewisite, adamsite, and clarke-1) is distinct from the above one, but is not any better. The products of their hydrolysis are poorly water-soluble, but, what is more important, they are highly toxic. Therefore, if such contaminants get into a sea medium from the places of their burial, large areas of the seabed will be poisoned by highly toxic substances, in particular, by inorganic compounds of trivalent arsenic. Life will be impossible in these regions. 

Lewisite s behaviour at leakage could be reminiscent of yperite it also has low solubility in water (0.05% at 20° C) and is considerably heavier than water (density 1.88 g/ml at 20° C). Yet, it is much more reactive than yperite and it is easily hydrolysed, thus the affected zone becomes even smaller than that of yperite. However, a specific feature of lewisite is its hydrolysis resulting in an oxide of the same toxicity. This oxide is a solid substance practically insoluble in water. The example of adamsite has just shown us the relativity of the notion of insolubility. 

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