Carbonyl diisocyanate synthesis

This seems a reasonable mechanism, as the reaction of MCgSiCNCS) with phosgene gives CO(NCS)j [45a] and the reaction of tributyltin(IV) isocyanate with phosgene has been utilized for the synthesis of carbonyl diisocyanate [22a] ... 

Reductive carbonylation of nitro compounds (in particular aromatic dinitro compounds) is an important target in industry for making diisocyanates, one of the starting materials for polycarbamates. At present diisocyanates are made from diamines and phosgene. Direct synthesis of isocyanates from nitro compounds would avoid the reduction of nitro compounds to anilines, the... 

J/n < 6,000). Often, no analytical data or structural characterization was provided. Room-temperature interfacial polycondensation methods were also investigated as a convenient alternative to classical polycondensations. Such methods were first reported for the preparation of polyamides and polyesters from the reaction of l,l -ferrocenyldi-carbonyl chloride with several diamines and diols. The synthesis of polyurethanes using this technique was also reported and involved the condensation of l,T-ferrocenedimethanol and l,T-bis(dihydroxyethyl)ferrocene with diisocyanates. Once again, however, these polymers possessed low molecular weights.The early research in these areas has been summarized and critically reviewed and will not be discussed further here. ... 

The synthesis of model compounds mimicking the structural characteristics of the possible subunits, and the comparison of their spectra with that of the hb polymer, represents a common method for assigning signals to subunits. This procedure, for the assignment of urea and urethane carbonyl carbon signals of a hb poly(urea urethane) synthesized from an AA (2,4-toluylene diisocyanate) and B2 B (diethanol amine) monomer [94], is shown in Figure 24.3. 

Triphosgene is used as a carbonylating agent in the synthesis of 2-tolyl isocyanate 262 and in the synthesis of 4,4 -diphenylmethane diisocyanate (MDI) 264 from the corresponding diamine in high yield (92%) [53]. 

The most widely employed synthetic route to aramids is based on the polycondensation of dicarboxylic acids with diamines in the presence of condensing agents. Good reviews on the synthesis of aramids have recently appeared (1-3). Recently, promising alternative synthetic routes to aramids have been reported and are described herein. These include the polycondensation of N-silylated diamines with diacid chlorides, the addition-elimination reaction of dicarboxylic acids with diisocyanates, and the palladium-catalyzed carbonylation polymerization of aromatic dibromides, aromatic diamines and carbon monoxide. 

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