The Influence of The Alcohol's Acidity on Organo‐Base Catalyzed Carbamate Formation From Aliphatic Isocyanates

ABSTRACT

This study presents findings on Lewis and Brønsted base catalysis in the reaction of aliphatic isocyanates with aliphatic and aromatic alcohols at room temperature and under solvent‐free conditions. The electronic properties of the alcohols were examined to determine their impact on reaction rates, using Lewis and Brønsted bases, as well as the Lewis acid dibutyltin dilaureate (DBTL), as a reference. The results for primary aliphatic alcohols showed that none of the organo‐bases could compete with DBTL in terms of catalytic activity. However, a strong dependence of the alcohols' acidity on the reaction rate was observed. With organo‐base catalysis, more acidic alcohols, particularly phenols, react faster than less acidic ones. The opposite trend was observed with DBTL. Selectivity tests revealed preferential consumption of the more acidic alcohol when base‐catalysis was used. DBTL causes aliphatic alcohols to react more readily than phenols. Accordingly, base catalysis offers high activity and selectivity in the carbamate formation from aromatic alcohols and aliphatic isocyanates.