Synthesis Of Diisocyanates Research Articles

Carbon2Polymer – Conceptual Design of a CO2‐Based Process for the Production of Isocyanates

AbstractThe capture of carbon dioxide and its utilization as a building block in chemical synthesis aim at reducing the depletion of fossil resources and the emission of greenhouse gases. The project Carbon2Chem®‐L5 is dedicated to the development of processes using CO2 for the production of polymer building blocks for polyurethanes. In this work, a process concept is presented for the CO2‐based synthesis of diisocyanates, the main starting material in polyurethane manufacture. Key parameters for process performance are discussed.

Furazan N-oxides. Part 3. Synthesis of di-isocyanates from strained norbornane furazan N-oxides

Thermolysis, at ca. 110 °C, of the strained norbornane furazan N-oxides (5)–(8) in toluene, saturated with sulphur dioxide, affords the isomeric 1,3-di-isocyantocyclopentanes (14)–(17). Product formation is explained by a mechanism involving cleavage of the furazan ring to cyclopentane-1,3- bis(nitrile oxides)[e.g.(9)], followed by 1,3-dipolar cycloaddition with SO2 to form bis-1,3,2,4-dioxathiazol-2-ones [e.g.(12)]. Subsequent extrusion of SO2 and rearrangement yields di-isocyanates [e.g.(14)] which were identified spectroscopically and by preparation of urethane and/or urea derivatives on reaction with alcohols and aniline. Compound (8) with aniline gives the cyclic biuret (20) rather than a bis-urea, the structure of the product being established by X-ray crystallography. In the absence of SO2 polymeric furoxans are formed.