At room temperature (70°F), phosgene is a poisonous gas



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Phosgene:

  • At room temperature (70°F), phosgene is a poisonous gas.

  • With cooling and pressure, phosgene gas can be converted into a liquid so that it can be shipped and stored. When liquid phosgene is released, it quickly turns into a gas that stays close to the ground and spreads rapidly

  • Phosgene can be formed when chlorinated hydrocarbon compounds are exposed to high temperatures. Chlorinated hydrocarbon compounds are substances sometimes used or created in industry that contain the elements chlorine, hydrogen, and carbon.

  • The vapors of chlorinated solvents exposed to high temperatures have been known to produce phosgene. Chlorinated solvents are chlorine-containing chemicals that are typically used in industrial processes to dissolve or clean other materials, such as in paint stripping, metal cleaning, and dry cleaning.

  • COCl2.

  • Industrially, phosgene is produced by passing purified carbon monoxide and chlorine gas through a bed of highly porous carbon, which acts as a catalyst. The chemical equation for their reaction is CO + Cl2 → COCl2

  • The reaction is exothermic, i.e. the reactor must be cooled to carry away the heat it produces. Typically, the reaction is carried out between 50°C and 150°C. Above 200°C, phosgene decomposes back into carbon monoxide and chlorine. Upon ultraviolet radiation in the presence of oxygen, chloroform forms significant amounts of phosgene via a radical reaction. Brown glass flasks for chloroform prevent this reaction.

  • Phosgene is produced by reacting equimolar amounts of carbon monoxide and anhydrous chlorine in the presence of a carbon catalyst under appropriate conditions of temperature and pressure. The great majority is used directly in closed systems on-site.

  • Phosgene is used as an intermediate in the manufacture of many organic chemicals. The largest amount (approximately 80% of world production) is used to produce toluene diisocyanate and other isocyanates used in polyurethane foam production, preparation of plastics, and pesticides. Accurate production figures are hard to determine since over 99% of phosgene production is "used on site". Approximately 3×106 tonnes of phosgene are used annually worldwide.

Hydrogen Cyanide:

  • Hydrogen cyanide is manufactured by oxidation of ammonia- methane mixtures under controlled conditions and by the catalytic decomposition of formamide. It may be generated by treating cyanide salts with acid, and it is a combustion by-product of nitrogen-containing materials such as wool, silk, and plastics and as a fumigant to kill rats. It is also used in electroplating metals and in developing photographic film. It is also produced by enzymatic hydrolysis of nitriles and related chemicals. Hydrogen cyanide gas is a by-product of coke-oven and blast-furnace operations

  • Hydrogen cyanide is used in fumigating; electroplating; mining; and in producing synthetic fibers, plastics, dyes, and pesticides. It also is used as an intermediate in chemical syntheses NIOSH IDLH (immediately dangerous to life or health) = 50 ppm

  • NIOSH IDLH (immediately dangerous to life or health) = 50 ppm

  • Molecular weight: 27.03 daltons

  • Boiling point (760 mm Hg): 78ºF (25.6ºC)

  • Freezing point: 8ºF (-13.4ºC)

  • Specific gravity (liquid): 0.69 (water = 1)

  • Vapor pressure: 630 mm Hg at 68ºF (20ºC)

  • Gas density: 0.94 (air = 1)

  • Water solubility: Flammable at temperatures >0ºF (-18ºC)

  • Flammability: flammable limits 3.9% to 21.8% at room temperature

  • Flammable range: 5.6% to 40% (concentration in air)

  • Incompatibilities: Hydrogen cyanide reacts with amines, oxidizers, acids, sodium hydroxide, calcium hydroxide, sodium carbonate, caustic substances, and ammonia. Hydrogen cyanide may polymerize at 122ºF to 140ºF.

  • Hydrogen cyanide is produced in large quantities by two processes.

    • In the Degussa process, ammonia and methane react at 1200 °C over a platinum catalyst:

    • This reaction is akin to steam reforming, the reaction of methane and water. In the Andrussov process, oxygen is added

    • CH4 + NH3 + 1.5O2 → HCN + 3H2O

    • In the laboratory, small amounts of HCN are produced by the addition of acids to cyanide salts of alkali metals:

    • This reaction is sometimes the basis of accidental poisonings because the acid converts the nonvolatile salt into the gaseous HCN.

  • Hydrogen cyanide may be synthesized directly from ammonia and carbon monoxide or from ammonia, oxygen (or air), and natural gas. It is a byproduct of the production of coke from coal and is recovered (along with hydrogen sulfide) from coke-oven exhaust gases. It may also be prepared by reacting a cyanide salt, e.g., calcium cyanide, with a strong acid, e.g., sulfuric acid, or by thermal decomposition of formamide. Because impure hydrogen cyanide can undergo spontaneous explosive polymerization and decomposition, a small amount of stabilizer (usually phosphoric acid) is added to it.

  • The principal use of hydrogen cyanide is in the manufacture of organic chemicals, e.g., acrylonitrile, methyl methacrylate, and adiponitrile, that are used in producing synthetic fibers and plastics. It is also used in the chemical laboratory, and is sometimes used in agriculture as a fumigant. Hydrogen cyanide is found in nature in some vegetable substances, e.g., bitter almond, peach stones, cherry and cherry laurel leaves, and sorghum; it is usually combined in glycoside molecules (see sugar) and is released when they are broken down by enzymes during metabolism.

  • Manufacturing activities releasing hydrogen cyanide include electroplating, metal, mining, metallurgy and metal cleaning processes. Additionally, hydrogen cyanide has some insecticide and fungicide applications (ATSDR, 1993). Fires involving some nitrogen-containing polymers, often found in fibers used in fabrics, upholstery covers, and padding, also produce hydrogen cyanide (Tsuchiya and Sumi, 1977).


Sarin:

  • There are many different methods of manufacture, but the Tokyo product appears to have been prepared using a procedure involving phosphorus trichloride and methyl iodide. The product was impure and diluted with acetonitrile to improve volatility. To stockpile Sarin, the product has to be pure ( 90-99% of the Iraqi Sarin degraded in < 2 years, whereas US Sarin only degraded a few % over 30 years ). The standard US government procedure( aka "di-di" ) starts with dimethyl methylphosphonate (DMMP), and ends with a distillation to remove impurities [19].




  • One component in the U.S. binary is methylphosphonyldifluoride (Code DF; CAS Registry Number 676-99-3) and the other is either isopropanol (CAS Registry Number 67-63-0) alone or OPA, where OPA is a mixture of isopropanol 72% with isopropylamine (CAS Registry Number 75-31-0) 28%.

  • sarin precursors dimethyl methylphosphanate, hydrogen fluoride, and isopropyl alcohol

  • In the final process, methylphosphonyl difluoride and methylphosphonyl dichloride was mixed with isopropyl alcohol to produce Sarin


VX:

  • Its chemical formula is CH3CH20-P(O)(CH3)-SCH2CH2N(C3H7)2 and is normally in its liquid state

  • Formal Chemical Name (IUPAC)
    S-2-(diisopropylamino)ethyl O-ethyl methylphosphonothioate

  • The vital precursors are phosphites, phosphorous chlorides, and alkyl-diethanolamines. Sales of these chemicals are restricted under the Chemical Weapons Convention, most likely in an attempt to make synthesis of nerve gases more difficult.

  • In particular, compounds containing the methyl-phosphite group are well-controlled, as the only known uses for these compounds are in the synthesis of nerve agents.

  • The four-stage VX production process is difficult, but the Muthanna (Iraq) scientists reverse engineered the recipe from a list of controlled chemicals issued by the Organization for the Prohibition of Chemical Weapons in The Hague. Saeed says he supervised production of his last two batches of liquid VX in April 1990 but that they failed to achieve his goal of 50 to 60 percent purity, and they deteriorated within a week. "It couldn't be used as a weapon," he insists.

A dose of 10mg· min/m3 of vapor is sufficient to cause death to 50 percent of individuals exposed, while 10mg of VX liquid on the skin of a man weighing 70 kilograms (roughly 150 pounds) is fatal to 50 percent of individuals exposed.

Lewisite:

  • Lew-isite is 2-chlorovinyl-dichloroarsine.

  • Acute toxicity levels for humans are not well defined but 0.05-0.1 mg/cm2 pro- duces erythema, 0.2 mg/cm2 produces vesication and a 15-minute exposure to a vapor concentration of 10 mg/m3 produces conjunctivitis. About 30 drops (2.6 mg), applied to the skin and not decontaminated, would be expected to kill an average man through systemic toxicity. With inhalation, the LCt50 in man is estimated to be about 1500 mg min/m3.

  • Chemically, lewisite is dichloro-2-chlorovinyl arsine, ClCHCHAsCl2

  • 2-Chlorovinylarsine dichloride (Lewisite 1) was produced in WW I and WW II as chemical warfare agent by Friedel Craft's alkylation of arsenic(III)chloride with ethine. During this production process the byproducts 2,2'-Dichlorodivinylarsine chloride (Lewisite II) and 2,2',2''-Trichlorotrivinylarsine (Lewisite III) are built.

  • The earlier producers favored the Levinstein Process, which consists of bubbling dry ethylene through sulfur monochloride, allowing the mixture to settle and (usually) distilling the remaining material. More recent production has involved chlorination of thiodiglycol, a relatively common material with a dual use as an ingredient in some inks. This method does not result in the solid byproducts of the Levinstein Process and can be more easily distilled.

  • Lewisite is an arsenical and as such would require unusually large amounts of arsenates in its production.


Sulfur Mustard:


  • Synonyms:

H and HD: Bis(2-chloroethyl) sulfide; bis(beta-chloroethyl) sulfide; di-2-chloroethyl sulfide; 1-chloro-2(beta-chloroethylthio)ethane; 2,2'-dichloroethyl sulfide; sulfur mustard; Iprit; Kampstoff "Lost"; mustard gas; senfgas, S-yperite; yellow cross liquid; yperite

HT: Mixture of bis(2-chloroethyl) sulfide and bis[2-(2-chloroethylthio)-ethyl]ether



  • Sulfur mustards are vesicants and alkylating agents. They are colorless when pure but are typically a yellow to brown oily substance with a slight garlic or mustard odor. H contains about 20 to 30% impurities (mostly sulfur); distilled mustard is known as HD and is nearly pure; HT is a mixture of 60% HD and 40% agent T (a closely related vesicant with a lower freezing point). Sulfur mustards evaporate slowly. They are very sparingly soluble in water but are soluble in oils, fats, and organic solvents. They are stable at ambient temperatures but decompose at temperatures greater than 149ºC.


SELECTED PRECURSORS

  • 2-Chloroethanol

  • Ethylene

  • Hydrochloric acid

  • Sodium sulfide

  • Sulfur dichloride

  • Sulfur monochloride

  • Thiodiglycol

  • Mass production was assisted by the fact that the production of dyes by I. G. Farben had given the German chemical industry experience with the production of the precursors used in synthesizing sulfur mustard. For instance, the mustard precursor thiodiglycol had been produced at the Ludwigshafen works for dye production in large lots even before the war. Thus, the initial demand was satisfied using the existing reactors for thiodiglycol production, and the plans for these reactors could be used to build new reactors to expand capacity (by the end of the war, sixty new reactors had been constructed to supplement the twelve which had existed at the beginning of the war). As a result, the Germans were able to rapidly build up stocks of sulfur mustard after beginning production at Leverkusen in Spring of 1917.

The table below shows how certain production processes for current commercial products are identical to those which might be used for the synthesis of agents used in chemical warfare.




Manufacturing process

Common commercial products

Chemical weapons

chlorination

Insecticides
Herbicides
Polymers, Dyestuffs
Pharmaceuticals
Solvants

Nitrogen and sulfur
mustards
Lewisite
Sarin
VX

fluorination

Polymers, Solvants
Pharmaceuticals
Pesticides, Herbicides
Cooling gases
Anesthesic Gases

Sarin
Soman

esterification

Insecticides
Solvants
Odorants
Pharmaceuticals

Sarin
Tabun
BZ

phosphoration

Insecticides
Flamme retardants
Oil additives

Sarin
Tabun
BZ

alkylation

Flamme retardants
Oil additives
Petrol chemicals

Sarin
Soman
VX






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