Urethane Formation with an Excess of Isocyanate or Alcohol: Experimental and Ab Initio Study

Cheikh, Wafaa; Rózsa, Zsófia Borbála; Camacho López, Christian Orlando; Mizsey, Péter; Viskolcz, Béla; Szőri, Milán; Fejes, Zsolt

doi:10.3390/polym11101543

Submit to this Journal Review for this Journal Edit a Special Issue

Article Menu

Printed Edition

A printed edition of this Special Issue is available at MDPI Books....

...

Open AccessArticle

Urethane Formation with an Excess of Isocyanate or Alcohol: Experimental and Ab Initio Study

Wafaa Cheikh

Zsófia Borbála Rózsa

Christian Orlando Camacho López

and

Institute of Chemistry, University of Miskolc, Miskolc-Egyetemváros A/2, H-3515 Miskolc, Hungary

Authors to whom correspondence should be addressed.

Polymers 2019, 11(10), 1543; https://doi.org/10.3390/polym11101543

Received: 29 August 2019 / Revised: 19 September 2019 / Accepted: 19 September 2019 / Published: 22 September 2019

(This article belongs to the Special Issue Functional Polyurethanes – In Memory of Prof. József Karger-Kocsis)

View Full-Text Download PDF

Browse Figures

Citation Export

Abstract

A kinetic and mechanistic investigation of the alcoholysis of phenyl isocyanate using 1-propanol as the alcohol was undertaken. A molecular mechanism of urethane formation in both alcohol and isocyanate excess is explored using a combination of an accurate fourth generation Gaussian thermochemistry (G4MP2) with the Solvent Model Density (SMD) implicit solvent model. These mechanisms were analyzed from an energetic point of view. According to the newly proposed two-step mechanism for isocyanate excess, allophanate is an intermediate towards urethane formation via six-centered transition state (TS) with a reaction barrier of 62.6 kJ/mol in the THF model. In the next step, synchronous 1,3-H shift between the nitrogens of allophanate and the cleavage of the C–N bond resulted in the release of the isocyanate and the formation of a urethane bond via a low-lying TS with 49.0 kJ/mol energy relative to the reactants. Arrhenius activation energies of the stoichiometric, alcohol excess and the isocyanate excess reactions were experimentally determined by means of HPLC technique. The activation energies for both the alcohol (measured in our recent work) and the isocyanate excess reactions were lower compared to that of the stoichiometric ratio, in agreement with the theoretical calculations. View Full-Text

Keywords: urethane formation; isocyanate excess; mechanism; ab initio; allophanate; kinetics

▼ Show Figures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Supplementary Material

Supplementary File 1:
PDF-Document (PDF, 354 KiB)

Share and Cite

MDPI and ACS Style

Cheikh, W.; Rózsa, Z.B.; Camacho López, C.O.; Mizsey, P.; Viskolcz, B.; Szőri, M.; Fejes, Z. Urethane Formation with an Excess of Isocyanate or Alcohol: Experimental and Ab Initio Study. Polymers 2019, 11, 1543. https://doi.org/10.3390/polym11101543

AMA Style

Cheikh W, Rózsa ZB, Camacho López CO, Mizsey P, Viskolcz B, Szőri M, Fejes Z. Urethane Formation with an Excess of Isocyanate or Alcohol: Experimental and Ab Initio Study. Polymers. 2019; 11(10):1543. https://doi.org/10.3390/polym11101543

Chicago/Turabian Style

Cheikh, Wafaa, Zsófia B. Rózsa, Christian O. Camacho López, Péter Mizsey, Béla Viskolcz, Milán Szőri, and Zsolt Fejes. 2019. "Urethane Formation with an Excess of Isocyanate or Alcohol: Experimental and Ab Initio Study" Polymers 11, no. 10: 1543. https://doi.org/10.3390/polym11101543

Find Other Styles

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Metrics

Abstract views Pdf views Html views

Article Menu

Printed Edition

Urethane Formation with an Excess of Isocyanate or Alcohol: Experimental and Ab Initio Study

Abstract

Supplementary Material

Share and Cite

Article Metrics

Article Access Statistics

Article Access Map by Country/Region

Further Information

Guidelines

MDPI Initiatives

Follow MDPI