Kinetics of hydroxymethyl phenols formation by in‐line FTIR spectroscopy

Abstract

The kinetics of phenol-formaldehyde prepolymers catalyzed by sodium hydroxide at various temperatures was studied. Several reactions were conducted with different phenol to formaldehyde as well as phenol to sodium hydroxide molar ratios. The React-IR system was used to monitor the reaction as well as to determine residual free phenol and formaldehyde.The changes in the concentrations of phenol and formaldehyde with the reaction time were determined. The value of the concentration of the hydroxide ion, [OH 2 ], was obtained by measuring the pH value of reaction mixture. The concentration of the hydroxide ion, [OH 2 ], expressed as a function of reaction time, was fitted by the six-order polynomial to the experimental data. On the basis of the proposed reaction scheme the kinetic model was developed.The kinetic parameters were obtained by adjusting the experimental evolution of phenol and formaldehyde during the synthesis. Using this method the changes in the concentrations of five species of hydroxymethyl phenols with the reaction time was also been calculated. The activation energy and preexponential factor have been calculated for individual reactions. The accuracy of the kinetic model was confirmed by comparing experimental concentration profiles of formaldehyde and phenol with the calculated ones for different molar ratios. The experimental tendencies are in agreement with the results of the model.

Online monitoring of synthesis and curing of phenol–formaldehyde resol resins by Raman spectroscopy

“…Since understanding of the advancement of resol resin synthesis and curing processes is essential for further development of the resins, methylolation and condensation reactions and structures of the resols have been followed and studied by various methods, such as FTIR spectroscopy [5,8,9], gel permeation chromatography (GPC) [10][11][12][13], 13 C NMR spectroscopy [14][15][16][17][18], and differential scanning calorimetry (DSC) [3,7,11,19]. However, none of these methods is well suited for gathering real-time information about the consumption of starting materials or structure of the resins during the resin processes, which could improve the safety and control of the synthesis and result in more uniform resin quality.…”

Influencing the Stability of Diaminomethane‐Containing Azacrown Ether Ligands in the Presence of Transition‐Metal Ions

“…Changes in band frequency and intensity following the addition of zinc chloride to a 3:1 solution of DMF/H 2 O were monitored in real time by using the ConcIRT software 25. The software interprets the net change in all peak intensities over a region of interest, in this instance 1800 to 700 cm –1 , and deconstructs that data into individual component spectra, which allow changes in the reaction profile to be visualised 26. This provides a rapid qualitative “fingerprint” of reaction behaviour intended for general insights into the mechanism 27.…”

Application of Fiber-Optic Attenuated Total Reflection-FT-IR Methods for In Situ Characterization of Protein Delivery Systems in Real Time

“…11 These in situ fiber optic probes have shown great success when characterizing and optimizing reaction conditions, kinetics, intermediates, and elucidating mechanisms for multi-component mixtures. 12-14 The application of ATR-FTIR to the study of crystal growth and nucleation shows its ability to yield valuable information from complex, multicomponent samples for pharmaceutical applications. 15, 16 Despite a proven track record for acquiring real time data for a variety of different types of samples relevant to pharmaceutical research, 17, 18 this methodology has not been applied to the field of therapeutic and diagnostic delivery systems often comprising buffer salt solutions, polymeric material, surfactant, and protein or other payload to be released.…”