Protection from phosgene

Thus, partial protection from phosgene-induced lethality was obtained by the phosgene pretreatment. TABLE 1-6 Acute Lethality of Phosgene in Mice ... 

An important example is the preparation of carbobenzoxy chloride (PhCH20C0Cl) from phosgene and benzyl alcohol. This compound is widely used for protection of amino groups during peptide synthesis (see 10-55). 

Personal Protective Equipment Phosgene is a severe respiratory tract and skin irritant, and contact with the liquid will cause frostbite. Respiratory protection requires positive-pressure-demand, self-contained breathing apparatus (SCBA), while skin protection requires chemical-protective clothing since phosgene gas can cause skin irritation and burns. NIOSH recommends protective suits from Responder (Kappler Co.), Tychem 10000 TM (DuPont Co.) or Teflon (DuPont Co.). 

Phosgene may be formed when chlorinated hydrocarbons are exposed to ultraviolet radiation in the presence of air [627]. Dichloromethane was found to contain trace quantities of phosgene after storage for a few days in clear glass flasks, despite being protected from exposure to direct sunlight [855]. Trichloromethane decomposes photooxidatively in a similar way to that described for its thermal oxidation (Section 3.3.3), the process differing in the... 

Bulk phosgene is kept in underground storage tanks of double shell construction in some facilities [1488]. This provides containment in the event of a leak from the inner wall, and protection from mechanical damage to the outer wall. If the outer shell also develops a leak then the surrounding earth would prevent a large scale release of gas [1488]. 

Hazardous Decomp. Prods. ffeated to decomp., emits toxic fumes of HCI gas, CO, CO2, phosgene emits toxic fumes under fire conditions NFPA ffealth 2, Flammability 3, Reactivity 2 Storage Air-, light-, and moisture-sensitive keep container tightly closed under Inert atmosphere store In explosion-proof refrigerator protect from light... 

Hazardous Decomp. Prods. Heated to decomp., emits highly toxic fumes of hydrogen chloride gas, chlorine, phosgene, CO NFPA Health 4, Flammability 2, Reactivity 0 Storage Sensitive to moisture, heat store refrigerated, away from oxidizing materials protect from moisture storage under inert atm. rec. 

Typical procedure. 2,5-Oxazolidinedione 667 [447] Into a suspension of finely ground glydne (15 g) in dry dioxane (750 mL), phosgene (for a safe source, see Chapter 7) was introduced in a fine stream at 45-50 °C with effident agitation. A clear solution was obtained after 5 h. This solution was filtered to remove unreacted glycine (1.7 g), and the dioxane was then removed under reduced pressure at a temperature below 40 °C with protection from moisture. The residue was... 

H.-l. Chen, H. Bai, M.-m. Xi, R. Liu, X.-j. Qin, X. Liang, W. Zhang, X.-d. Zhang, W.-l. Li and C.-x. Hai, Ethyl pyruvate protects rats from phosgene-induced pulmonary edema by inhibiting cyclooxygenase2 and inducible nitric oxide synthase expression, / Appl Toxicol, 2013, 33, 71-77. 

Many procedures for the formation of carboxylic acid amides are known in the literature. The most widely practiced method employs carboxylic acid chlorides as the electrophiles which react with the amine in the presence of an acid scavenger. Despite its wide scope, this protocol suffers from several drawbacks. Most notable are the limited stability of many acid chlorides and the need for hazardous reagents for their preparation (thionyl chloride, oxalyl chloride, phosgene etc.) which release corrosive and volatile by-products. Moreover, almost any other functional group in either reaction partner needs to be protected to ensure chemoselective amide formation.2 The procedure outlined above presents a convenient and catalytic alternative to this standard protocol. 

The formation of peptides from Leuchs anhydrides proceeds without the use of protecting groups, and no racemisation occurs. However, the use of phosgene cannot be considered a prebiotic process ... 

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