Lead chloride-phosgene

CNS depression, cardiac arrythmias, respiratory depression, and death. Halo-genated hydrocarbons decompose when heated and become a toxic gas (e.g., hydrogen chloride, phosgene). Evaporation of halogenated hydrocarbons as propellants causes intense cold, which leads to numbness. These gases have been used as topical analgesics. 

The halogenocarbonates PbCb.PbCOj and PbBr2.PbCOj are isomorphousw i< , but the corresponding iodide could not be made. The chlorocarbonate PbCb.PbCOa is present in nature as the mineral phosgenite, and can be made by the action of phosgene upon lead hydroxide or by the action of carbon dioxide upon a solution of lead chloride. Natural and synthetic phosgenite have been shown to have identical crystal structures. 

Because phosgene reacts with water, great care must be taken to prevent contamination with traces of water since this could lead to the development of pressure by hydrogen chloride and carbon dioxide. Wet phosgene is very corrosive therefore phosgene should never be stored with any quantity of water (4). 

V-Phenylsuccinimide [83-25-0] (succanil) is obtained in essentially quantitative yield by heating equivalent amounts of succinic acid and aniline at 140—150°C (25). The reaction of a primary aromatic amine with phosgene leads to formation of an arylcarbamoyl chloride, that when heated loses hydrogen chloride to form an isocyanate. Commercially important isocyanates are obtained from aromatic primary diamines. 

Guanidines have been prepared by the reaction between an amine, or an amine salt, and a host of other reagents, such as a thiourea in the presence of lead or mercuric oxide [83, 157, 158], carbodi-imides [140, 174, 175],calcium cyanamide [176, 177], isonitrile dichlorides [178—180], chloroformamidines [181], dialkyl imidocarbonates [182], orthocarbonate esters [183], trichloro-methanesulphenyl chloride [184], and nitro- or nitroso-guanidines [185-188]. Substituted ureas can furnish guanidines, either by treatment with amines and phosphorus oxychloride [189], or by reaction with phenylisocyanate [190] or phosgene [191]. 

Reaction of bis(2-chloroethyl )amine with phosgene affords the corresponding carbamoyl chloride (J ). Acylation of estradiol (3) with this reagent leads to estramustine... 

The use of activated anthranihc acid derivatives facUitates the preparation of the amides in those cases where the amines are either umeactive or difficult to obtain. Thus, reaction of (87-1) with phosgene gives the reactive the isatoic anhydride (89-1). Condensation of that with ortho-toluidine leads to the acylation product (89-2) formed with a simultaneous loss of carbon dioxide. This is then converted to the quinazolone (89-3) by heating with acetic anhydride. Reaction with sodium borohydride in the presence of aluminum chloride selectively reduces the double bond to yield the diuretic agent metolazone (89-4) [99]. 

An entirely different method for the preparation of X -phosphorins utilizes phosphine chlorides 36 or 40. Treatment with bases leads to HCI elimination and to the formation of the X -phosphorins 37 and 41, respectively. The phosphine chlorides can be prepared from cyclic phosphinic acids 34 by reduction with diphenylsilane to the cyclic phosphines 35 followed by chlorination with phosgene. Alternatively,... 

Preparation of oxazole Cyclocondensation of amides, through dehydration, leads to the formation of corresponding oxazoles. This synthesis is known as Robinson-Gabriel synthesis. A number of acids or acid anhydrides, e.g. phosphoric acid, phosphorus oxychloride, phosgene and thionyl chloride, can bring about this dehydration. 

Carbamates have mainly been used in solid-phase synthesis as linkers and protective groups for amines (see Sections 3.6.2 and 10.1.10.1). Carbamates are generally prepared by treating amines with aryl carbonates or chloroformates, which can be prepared from alcohols and phosgene or synthetic equivalents thereof. The alternative route, in which carbamates, isocyanates, or carbamoyl chlorides are reacted with alcohols, is less widely used, but can also lead to satisfactory results on insoluble supports (Tables 14.7 and 14.8). 

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