Isocyanates allophanoyl chlorides

The in situ generated disubstituted ureas (26) also react with phosgene to yield thermally unstable allophanoyl chlorides (27) and chloroformamides (28) (75). As shown in Figure 5, the allophanoyl chlorides eliminate hydrogen chloride to form the isocyanate. The chloroformamides, however, yield chloroformamidine-A/-carbonyl chloride (29), which decomposes to yield both carbodiimides (30) and isocyanide dichlorides (31). The carbodiimides simply contribute to yield loss. The isocyanide dichlorides, although present in small amounts, are a contributor to chlorine-containing impurities which detrimentally affect product performance. 

Cumulenes 195 react readily with 2 equiv of an alkyl or aryl isocyanate to yield nitrilium salts 198, with either allophanoyl chlorides 199 or carbamoyl chlorides 200 as side products. Allophanoyl chlorides 199, when treated with antimony pentachloride, cyclize to crystalline oxadiazinium salts 201, which were found to be unstable (Scheme 33) <1995S820>. 

Boron chloride Allophanoyl chlorides from isocyanate molecules... 

The aliphatic-aromatic isocyanate dimer 5 is obtained in the cyclization of the corresponding allophanoyl chloride in the presence of pyridine as the hydrogen chloride scavenger. Allophanoyl chlorides are readily obtained from aliphatic or aliphatic/aromatic ureas and phosgene. ... 

Carbamoyl chlorides 258 react with isocyanates, in the presence of SnCLt, to give the allophanoyl chlorides 259. ... 

In the reaction of chlorocarbonyl isocyanate with secondary amines, allophanoyl chlorides are formed, which are readily dehydrochlorinated to give dialkylaminocarbonyl isocyanate, which dimerizes by a [4+2] cycloaddition reaction to give 481 ". ... 

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