A Kinetic Study of the Urea–Formaldehyde Reaction.

Smythe, L.E.

doi:10.1021/j150452a001

Cited by 24 publications

(8 citation statements)

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“…The foundations to the understanding of this complex reaction network have been laid out by Kadowaki. Later, Smythe, Crowe and Lynch, de Jong and de Jonge, Landqvist, and Kveton reported on reaction pathways, reaction mechanisms, and reaction kinetics of the main components. Up to now, industrial processes for the production of UF resins are typically controlled by temperature and pH value.…”

Section: Introductionmentioning

confidence: 99%

Quantitative and qualitative ¹H, ¹³C, and ¹⁵N NMR spectroscopic investigation of the urea–formaldehyde resin synthesis

Steinhof

Kibrik

Scherr

et al. 2014

Magnetic Reson in Chemistry

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Urea-formaldehyde resins are bulk products of the chemical industry. Their synthesis involves a complex reaction network. The present work contributes to its elucidation by presenting results from detailed NMR spectroscopic studies with different methods. Besides (1)H NMR and (13)C NMR, (15)N NMR spectroscopy is also applied. (15)N-enriched urea was used for the investigations. A detailed NMR signal assignment and a model of the reaction network of the hydroxymethylation step of the synthesis are presented. Because of its higher spectral dispersion and the fact that all key reactions directly involve the nitrogen centers, (15)N NMR provides a much larger amount of detail than do (1)H and (13)C NMR spectroscopy. Symmetric and asymmetric dimethylol urea can be clearly distinguished and separated from monomethylol urea, trimethylol urea, and methylene-bridged urea. The existence of hemiformals of methylol urea is confirmed. 1,3,5-Oxadiazinan-4-on (uron) and its derivatives were not found in the reaction mixtures investigated here but were prepared via alternative routes. The molar ratios of formaldehyde to urea were 1, 2, and 4, the pH values 7.5 and 8.5, and the reaction temperature 60 °C.

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Section: Introductionmentioning

confidence: 99%

Quantitative and qualitative ¹H, ¹³C, and ¹⁵N NMR spectroscopic investigation of the urea–formaldehyde resin synthesis

Steinhof

Kibrik

Scherr

et al. 2014

Magnetic Reson in Chemistry

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show abstract

“…The concentration of formaldehyde in the reaction mixture was determined by titration method (Smythe, 1947). In brief, immediately after the reaction had been initiated by mixing both the reactants (formaldehyde and urea), a portion of 0.5 mL was withdrawn periodically from the reactor and immediately cooled in an ice bath.…”

Section: Measurement Of Formaldehyde Concentration By Titrationmentioning

confidence: 99%

“…The complex reaction between urea and formaldehyde, which is technically important to produce urea-formaldehyde resins, was chosen as a model. According to Smythe ( 1947Smythe ( , 195 1 , 1952Smythe ( , 1953, Jong and Jonge (1953), Ninakawa (1955Ninakawa ( , 1956) and Glauert (1957), the mechanism of this reaction mainly depends on pH and the molecular ratio of urea to formaldehyde. The following complex reaction occurs in an alkaline solution.…”

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confidence: 99%

Differential thermal analysis of reaction kinetics in pseudo‐isothermal state Part 2. Complex reaction

Matsuda

Goto

1984

Can J Chem Eng

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The complex reaction between urea and formaldehyde is studied by the simultaneous method of DTA in pseudoisothermal state and conventional titration, and the kinetic parameters and the heat of reaction are evaluated. This reaction is technically important in the production of urea‐formaldehyde resins. The conversions were determined from both the experimental DTA data and the concentration change of formaldehyde with time. By using the available values of the heat of reaction, the rate constants then could be obtained. The experimentally determined activation energies were in good agreement with those reported in the literature.

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“…The kinetics of urea-formaldehyde polycondensations also have been investigated and summarized recently (129).…”

Section: Hooc(ch2)4cooh + Hoch2chohch2ohmentioning

confidence: 99%

Polymerization

Winding¹

1948

Ind. Eng. Chem.

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A Kinetic Study of the Urea–Formaldehyde Reaction.

Cited by 24 publications

References 2 publications

Quantitative and qualitative ¹H, ¹³C, and ¹⁵N NMR spectroscopic investigation of the urea–formaldehyde resin synthesis

Quantitative and qualitative ¹H, ¹³C, and ¹⁵N NMR spectroscopic investigation of the urea–formaldehyde resin synthesis

Differential thermal analysis of reaction kinetics in pseudo‐isothermal state Part 2. Complex reaction

Polymerization

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A Kinetic Study of the Urea–Formaldehyde Reaction.

Cited by 24 publications

References 2 publications

Quantitative and qualitative 1H, 13C, and 15N NMR spectroscopic investigation of the urea–formaldehyde resin synthesis

Quantitative and qualitative 1H, 13C, and 15N NMR spectroscopic investigation of the urea–formaldehyde resin synthesis

Differential thermal analysis of reaction kinetics in pseudo‐isothermal state Part 2. Complex reaction

Polymerization

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Product

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Quantitative and qualitative ¹H, ¹³C, and ¹⁵N NMR spectroscopic investigation of the urea–formaldehyde resin synthesis

Quantitative and qualitative ¹H, ¹³C, and ¹⁵N NMR spectroscopic investigation of the urea–formaldehyde resin synthesis