Hadeer Q. Waleed, Béla Viskolcz and Béla Fiser
Abstract
A general mechanism for catalytic urethane formation in the presence of acid catalysts,
dimethyl hydrogen phosphate (DMHP), methanesulfonic acid (MSA), and trifluoromethanesulfonic
acid (TFMSA), has been studied using theoretical methods. The reaction of phenyl isocyanate
(PhNCO) and butan-1-ol (BuOH) has been selected to describe the energetic and structural features
of the catalyst-free urethane formation. The catalytic activities of DMHP, MSA, and TFMSA have
been compared by adding them to the PhNCO–BuOH model system. The thermodynamic properties
of the reactions were computed by using the G3MP2BHandHLYP composite method. It was revealed
that in the presence of trifluoromethanesulfonic acid, the activation energy was the lowest within
the studied set of catalysts. The achieved results indicate that acids can be successfully employed in
urethane synthesis and the mechanism was described.
Keywords: composite method; acid catalysts; polyurethane; polymers; materials