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. 

Treatment of allophanoyl chlorides 241 with a base, such as triethylene diamine, led to the formation of 1,3-diazetidinediones 242 (Equation 31) <1978JOC4530>. 

Cyclic carbodiimides also undergo a rapid reaction with phosgene in methylenechloride to form the expected adducts 55, which on hydrolysis give cyclic allophanoyl chlorides 56.22... 

In the case of N,N -dialkyl ureas, phosgene is attacked by both oxygen and nitrogen atoms to give a mixture of chloroformamidinium chlorides (A) (0-acylation of the ureas) and allophanoyl chlorides (B) (N-acylation) as shown in scheme 155 (Ref. 211). 

Significant formation of allophanoyl chlorides, RNHC(0)NR C(0)C1, does not take place. Further, the formation of the gaseous co-product COS gives this reaction a considerable advantage over the corresponding use of phosphorus(V) chloride, the co-product, liquid P(S)Cl3, being very difficult to remove [2083a]. 

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 preparation of aliphatic diisocyanates, using bisacylazides, has to be conducted with caution because an explosion occurred in the preparation of ethylene diisocyanate by using this method (13). Ethylene diisocyanate is readily obtained by dehydrochlorination of a heterocyclic allophanoyl chloride derivative obtained in the phosgenation of ethyleneurea (14). 

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. ... 

Bicyclic aliphatic diisocyanate dimers as masked diisocyanates are also obtained from the corresponding allophanoyl chlorides and triethylamine. ... 

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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