Kinetics of the hydroxymethylation of phenols in dilute aqueous solution

Abstract

The hydroxymethylation of phenols has been investigated in the pH range 1-11 and between 7 S 1 3 0 " C in dilute aqueous solution.The reaction appeared to be bimolecular. Below about p H = 4 the rates were found to be proportional to the concentration of the hydrogen ions. while a proportionality to the concentration of the hydroxyl ions was observed in rrore alcaline solutions. An influence of the concentration of buffers on the rates has not been observed. The presence of small amounts of triethanolamine does not influence the rate of the reaction. The mechanism of the reaction is discussed.

Modelling of phenolic resin polymerisation

“…12 it seems that there is a minimum in the graph of the kinetic constant K 1;w versus the pH value. De Jong and De Jonge [35] studied the formaldehyde±phenol reaction catalysed with sulphuric acid in the pH range of 2.65±5.80 and found a minimum of the kinetic constant for pH 4.3.…”

Polymers Based on Phenols

“…Early work focused on the rate of reaction, either by the disappearance of phenol and formaldehyde 80 or by the appearance of hydroxymethyl phenols 81 -83 . It was shown that the rate of reaction between phenol and formaldehyde is a function of pH 80 , suggesting that the overall reaction proceeds with the generation of a phenolic anion, followed by the addition of formaldehyde 1,6 , generating a complex mixture of different hydroxymethyl phenol compounds-the resole resin (Scheme 14). Addition of formaldehyde can occur at three sites; the two sites ortho to the phenolic OH and one site para to the OH.…”