Abstract: The present invention is the novel synthesis of sterically hindered penta-substituted guanidines by a process in which (1a) an isocyanate is reacted first with a di-substituted amine or (1b) a urea is reacted with two moles of a mono-substituted amine to form a tri-substituted urea followed by (2) treatment of the tri-substituted urea with an activating agent before reacting with a second di-substituted amine in the presence of a base.

Abstract: A process for preparing isocyanates comprising contacting carbon dioxide and a primary amine in the presence of an aprotic organic solvent and a base selected from the group consisting of a phosphazene compound, an organic, nitrogenous base and mixtures thereof, wherein the organic, nitrogenous base selected from the group consisting of guanidine compounds, amidine compounds, tertiary amines and mixtures thereof to produce the corresponding ammonium carbamate salt, reacting the ammonium carbamate salt with an anhydride dehydrating agent to produce a product stream comprising the corresponding isocyanate, the aprotic organic solvent and the base salt derived from the anhydride, separating the base salt from the product stream, recovering and recycling the base, and regenerating and recycling the anhydride dehydrating agent.