Diisocyanate Dimethyl carbonate

Daicel Chemical Industries in Japan patented a promising phosgene-free process involving the reaction of an aliphatic diamine with dimethyl carbonate (DMC) to produce carbamate esters, which are then thermally converted to the corresponding aliphatic diisocyanates [38] (Scheme 5.4). It is noteworthy that this process could be a total phosgene-free process since the reactant, DMC, can be made directly from methanol and carbon dioxide (or urea) and eliminates the use of phosgene [39]. 

Daicel Chemical Industries, Ltd., has patented a process for reacting diamines, such as isophorone diamine (IPDA), with dimethyl carbonate. The condensation is accomplished in the presence of an alkaline catalyst, such as methanolic sodium methylate at 70 °C, to produce the diurethane. Treatment of the diurethane with hydrogenated terphenyl containing manganese acetate at 230 °C in vacuo produces isophorone diisocyanate by thermal decomposition. This non-phosgene process has a reported product yield of 93% of IPDI containing 1% isophorone monoisocyanate. 

NOTE - Petrochemical plants also generate significant amounts of solid wastes and sludges, some of which may be considered hazardous because of the presence of toxic organics and heavy metals. Spent caustic and other hazardous wastes may be generated in significant quantities examples are distillation residues associated with units handling acetaldehyde, acetonitrile, benzyl chloride, carbon tetrachloride, cumene, phthallic anhydride, nitrobenzene, methyl ethyl pyridine, toluene diisocyanate, trichloroethane, trichloroethylene, perchloro-ethylene, aniline, chlorobenzenes, dimethyl hydrazine, ethylene dibromide, toluenediamine, epichlorohydrin, ethyl chloride, ethylene dichloride, and vinyl chloride. 

Tosyl isocyanate reacts with dimethyl sulfoxide to give the expected exchange products, dimethylsulfllimine and carbon dioxides Sulfonyl diisocyanate reacts with two equivalents of dimethyl sulfoxide in acetonitrile to give sulfonyl bis(dimethylsulfilimine) 169 in 83 % yield o ... 

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