Next Article in Journal
Two Ways to Examine Differential Constitutive Equations: Initiated on Steady or Initiated on Unsteady (LAOS) Shear Characteristics
Next Article in Special Issue
Analysis of the Cross-Linking Reaction of Lignin with Triethyl Phosphate by MALDI-TOF and 13C NMR
Previous Article in Journal
Epoxidized Jatropha Oil as a Sustainable Plasticizer to Poly(lactic Acid)
Previous Article in Special Issue
Investigation on the Influence of Chain Extenders on the Performance of One-Component Moisture-Curable Polyurethane Adhesives
Article Menu
Issue 6 (June) cover image

Export Article

Open AccessArticle
Polymers 2017, 9(6), 203; doi:10.3390/polym9060203

New Mechanism Proposed for the Base-Catalyzed Urea–Formaldehyde Condensation Reactions: A Theoretical Study

1
The Yunnan Province Key Lab of Wood Adhesives and Glued Products, Southwest Forestry University, Kunming 650224, China
2
Key Lab for Forest Resources Conservation and Utilisation in the Southwest Mountains of China, Southwest Forestry University, Ministry of Education, Kunming 650224, China
3
School of Chemical Science and Technology, Yunnan University, Kunming 650091, China
*
Authors to whom correspondence should be addressed.
Academic Editor: Antonio Pizzi
Received: 12 May 2017 / Revised: 27 May 2017 / Accepted: 27 May 2017 / Published: 2 June 2017
(This article belongs to the Collection Polymeric Adhesives)
View Full-Text   |   Download PDF [1711 KB, uploaded 2 June 2017]   |  

Abstract

Base-catalyzed urea–formaldehyde condensation reactions were investigated by using a quantum chemistry method. It was found that monomethylolurea or N,N’-dimethylolurea can produce the methyleneurea intermediate (–HN–CO–N=CH2) with the catalysis of base. The E1cb (unimolecular elimination of conjugate base) mechanism was identified for the formation of such an intermediate. The potential energy barrier was theoretically predicted to be 59.6 kJ/mol for the E1cb step, which is about half of that of previously proposed SN2 (bimolecular nucleophilic substitution) mechanism. In the subsequentcondensation reactions, Michael addition reactions that lead to different condensed structures can occur between the methyleneurea intermediate and the anions produced from methylolureas under alkaline conditions. Based on the theoretical calculations on the kinetics and thermodynamics of the selected reactions, the competitive formations of methylene linkages, ether linkages and uron were discussed in combination with our previous experimental observations. View Full-Text
Keywords: urea–formaldehyde; base-catalyzed; condensation; mechanism urea–formaldehyde; base-catalyzed; condensation; mechanism
Figures

Figure 1

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. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Li, T.; Cao, M.; Liang, J.; Xie, X.; Du, G. New Mechanism Proposed for the Base-Catalyzed Urea–Formaldehyde Condensation Reactions: A Theoretical Study. Polymers 2017, 9, 203.

Show more citation formats Show less citations formats

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

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Polymers EISSN 2073-4360 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top